Preface

Dermatoscopy is a fast, easy-to-learn, low-cost, and non-invasive diagnostic method utilizing the Rayleigh scattering phenomenon to visualize epidermal and subepidermal structures. It has become increasingly popular for allowing visualization of structures that are impossible to see with the naked eye. This book presents comprehensive information on dermatoscopy and its use in detecting skin lesions.

Following the Introductory Section, the second section of this book discusses basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), neoplasms responsible for more than 95% of all skin cancer cases worldwide. Chapter 2 by Prof. Larisa Prpic Massari summarizes the data on epidemiology, genetic background, and the clinical and dermatoscopic presentation of the most common histopathological variants of BCC. In Chapter 3, Dr. Alise Balcere presents an up-to-date review on actinic keratosis (AK) and intraepithelial carcinoma (IEC). This chapter discusses the clinical and histological classification of AK, the SCC progression model, and dermatoscopic clues to AK and IEC.

The third section of this book presents information on melanocytic lesions with a focus on combined nevi, which are common melanoma simulators. In Chapter 4, Prof. Jelena Stojkovic-Filipovic and Miljan Vlahovic define combined nevi and discuss their most common variants and their matching dermatoscopic and histopathologic presentations.

The fourth section of this book focuses on special sites. In Chapter 5, Dr. Wojciech Adamski, an ophthalmologist, and Dr. Kinga Adamska, a dermatologist, present their collection of pigmented lesions affecting the eyelid margin and share their approach to management.

The fifth section includes two miscellaneous chapters. Chapter 6 by Dr. Çetinarslan Tubanur, Dr. Ece Gökyayla, and Prof. Aylin Türel Ermertcan presents the authors' research on inflammoscopy of palmoplantar dermatoses. Rich descriptions of dermatoscopic clues of psoriasis, eczema, lichen planus, and lichen nitidus, a wide range of keratodermas, and fungal and bacterial infectious diseases (including syphilis) are the best examples of where dermatoscopy can be applied. Finally, Chapter 7 by Dr. Walid Al-Zyoud and Dr. Dana Erekat summarizes the precautions taken in the dermatological office during the COVID pandemic. The chapter stratifies procedures into risk groups and advises on how to safely manage patients, including those requiring skin checkups.

I wish to express my gratitude to all the authors for their contributions and IntechOpen for their support and commitment to the world of open-access literature.

> **Paweł Pietkiewicz** General and Oncological Surgery Clinic I, Greater Poland Cancer Center, Poznań, Poland

Section 1 Introduction

#### **Chapter 1**

## Introductory Chapter: Dermatoscopy

*Paweł Pietkiewicz*

#### **1. Introduction**

Although dermatoscopy was born as epiluminiscence microscopy many decades ago, it still develops, and hundreds of new papers are being published each year in scientific journals on new discoveries, significance of particular structures, and new applications. Dermatoscopy is no longer just a skin cancer screening technique, but can be employed to a wide variety of non-neoplastic conditions: trichoscopy for the diseases of hair and scalp, inflammoscopy for inflammatory skin diseases, mucoscopy for mucous membranes, onychoscopy for the diseases of nail apparatus, infectoscopy for identification of inflammatory diseases, endomodermatoscopy for skin parasitoses, and even dentoscopy for examining the teeth [1–3]. The systematization of the terminology in dermatoscopy and inflammoscopy terminology made the method more accessible for the beginners [4, 5].

#### **2. The scope of dermatoscope**

We are living in the era of Internet, smartphones, and artificial intelligence (AI)-driven networks that shape our practices and everyday environment to make it seemingly more convenient and remote, and COVID pandemic accelerated this process even more. In this chase, we are gradually losing the direct contact with our patients, which might lead to delayed or imprecise diagnosis of skin conditions. While taking advantage of what the modern technology provides us with, we should keep in mind that the simplest and direct examination, including taking medical history, visual inspection, and palpation, should still remain a gold standard. Dermatoscope is fast to apply and inexpensive auxiliary tool that complements physical examination and gives a better insight into the true nature of the inspected lesion. Nowadays, in many situations, dermatoscopists are able to diagnose certain diseases or predict a number of details commonly provided in pathology reports without actually taking a biopsy. Dermatoscopes proved to be useful in multispecialty settings. These can be used by dermatologists, oncologists, surgeons, general practitioners, radiotherapists, urologists, hematologists, pathologists, and many more. Being able to identify dermatoscopic structures can be the first step into pattern analysis and learning dermatoscopy-pathology correlations [6–8]. Currently, it is possible to assess tumor margins better than with a naked eye, which lowers the costs of treatment and lowers the risk of recurrence after radiotherapy and skin surgery, especially in Mohs micrographic surgery [9–14]. Particular structures, such as pigmented clods, or vascular clues, can be predictors of more invasive basal and squamous cell carcinomas (BCC, SCC) [15–20]. Consequently, it has an impact on planning the management (namely choosing between the surgery, topical treatment, radiotherapy, or photodynamic therapy) or monitoring its efficacy [21–24].

Dermatoscopy always provides meaningful information. It may either confirm or rule out initial clinical diagnosis or point out to the other diagnosis that was not considered initially, especially inflammatory skin diseases. Even if the lesion turns out to be mysterious to the eye of dermatoscopist, dermatoscopy may exclude some of the diagnoses and lead to change in the diagnostic plan and management, influencing the decisive process (e.g., rapid biopsy)and saving the patient from the consequences of diagnostic pitfall, unnecessary expenses for non-optimal therapy and its side effects, lost time till the final diagnosis, unnecessary stress and suffering, and in some cases, also patient's life/health from disease progression.

When combined with a device to capture images (smartphone, single-lens reflex camera, compact camera, or more convenient professional video dermatoscope) it proves to give additional info on already excised lesions. With a digitized image, physician is able to verify his initial diagnosis and reconsult the slides with the pathologist in order to avoid medical errors if the initial diagnosis does not match the report. It enables the identification of cases of mismatched specimens, misdiagnosis, or invalid tumor subtype. Also, based on the significance of the spectrum of colors seen in dermatoscopy, it is possible to detect underestimated Breslow thickness, as gray and blue colors mark the distribution of melanin in papillary and reticular dermis [25]. This process of confronting certain digitized features with the pathology can be called retroscopy, which is also a useful method to learn the morphology-histology correlations. Digital dermatoscopy or monitoroscopy can also be used for monitoring inflammatory skin diseases, predicting the therapeutic outcomes and resistance/susceptibility to certain therapies [26, 27]. AI is being increasingly implemented in all areas of healthcare. AI-assisted wide area digital dermatoscopy is a method enabling to combine multiple separate dermatoscopic images of the same large skin lesion into one map to enable precise assessment of structures and delineation [28–30]. Assessing the borders in melanoma is crucial for radical excision. In some lesions, this border is vague, but dermatoscopy with wavelengths close to ultraviolet light is able to enhance this process [31]. Another computer-assisted add-on to dermatoscopy and inflammoscopy is skin parameter map obtained with multispectral dermatoscopy [32–34]. Pattern recognition algorithms may have a particularly important role in the future development of digital dermatoscopy, supporting the diagnostic process and assisting the management, especially for non-experts [35]. This applies not only to AI-assisted assessment of dermatoscopic images but also photographs obtained with total body photography (TBP) [36–40]. Combining sequential TBP with the sequential digital dermatoscopy imaging increases the accuracy of detection of smaller, less invasive melanomas but also reduces the number of unnecessary surgical procedures [41]. As handheld dermatoscopy is cost-effective, easy to apply and learn, it is this diagnostic technique that should serve as a basic auxiliary device in skin cancer screening.

*Introductory Chapter: Dermatoscopy DOI: http://dx.doi.org/10.5772/intechopen.102974*

#### **Author details**

Paweł Pietkiewicz General and Oncological Surgery Clinic I, Greater Poland Cancer Center, Poznań, Poland

\*Address all correspondence to: p.pietkiewicz@mp.pl

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Section 2 Skin Cancer

#### **Chapter 2**

## Dermatoscopic Features of Basal Cell Carcinoma

*Tina Zagar, Nika Hlaca and Larisa Prpic-Massari*

#### **Abstract**

Basal cell carcinoma is the most common type of non-melanoma skin cancers, frequently observed in fair-skinned individuals. The major risk factors for developing basal cell carcinoma are environmental exposures, phenotypic and genetic traits, and immunosuppression. The diagnosis of basal cell carcinoma is based upon clinical examination and dermatoscopy findings and finally confirmed by histopathological analysis. There are five main clinicopathologic types of basal cell carcinoma, specifically, superficial, nodular, pigmented, morpheaform, and fibroepithelial variant. The dermatoscopic feature of all BCC is the absence of a pigment network. Dermatoscopy structures are further classified as vascular, pigment-related, and non-vascular/non-pigment-related structures. Vascular structures include arborizing vessels and short fine telangiectasias, while pigmented structures comprise maple leaf-like areas, spoke-wheel areas, multiple blue-gray globules, in-focus dots, and concentric structures. Additional structures such as ulcerations, multiple small erosions, multiple aggregated yellow-white globules, shiny white-red structureless areas, and white streaks are considered non-vascular/ non-pigmented structures. As treatment options highly depend on the type of BCC, dermatoscopy is of great value in management strategy, assessment of margins, and evaluation of response to non-ablative therapies.

**Keywords:** algorithms, dermatoscopy, disease management, carcinoma, basal cell, carcinoma, basal cell/diagnosis, skin neoplasms

#### **1. Introduction**

Basal cell carcinoma (BCC) is the most common type of non-melanoma skin cancers (NMSCs), most frequently observed in fair-skinned individuals. BCCs originate from the pluripotent cells of the bulge region of the hair shaft and the interfollicular epidermis. Even though BCCs rarely metastasize, they are locally invasive and destructive, and thus if not treated on time, present a therapeutic challenge. There are five main clinicopathologic types of BCC, specifically, superficial, nodular, pigmented, morpheaform, and fibroepithelial (also familiar as fibroepithelioma of Pinkus) [1].

Regarding epidemiology, the incidence of BCC correlates well with geographic location, with the southern hemisphere and regions closer to the equator having higher incidence. The average amount of annual exposure to ultraviolet radiation (UVR) has insignificant correlation with the incidence of BCCs. Additionally, fair skin phototypes and increasing age are also well correlated with the incidence of

BCC [1, 2]. The median age for acquiring BCC is 68. However, the development of BCC is mostly related to skin color, with white populations being particularly prone to the development of BCC. Moreover, men have a higher risk for acquiring BCC than women, although the rise in BCC among younger women has been noted lately. According to the American Cancer Society, currently, the incidence of BCCs is on the rise by more than 10% per year in the United States. Similar increases in incidence have been observed worldwide over the last two decades [3, 4].

The risk factors for developing BCC are environmental exposures, phenotypic characteristics, genetic traits, and immunosuppression. UVR is the most significant risk factor, particularly intermittent intense episodes of UV exposure and sunburns early in life [4, 5]. Among phenotypic traits, fair skin pigmentation, light hair and eye color, and poor tanning ability are the most common risk factors for BCC [5]. Furthermore, indoor tanning usage, chronic immunosuppression, and to a certain degree long-term photochemotherapy (PUVA) as well as ionizing radiation influence the risk for BCC development [6–8]. Additionally, chronic immunosuppression may increase the risk for BCC [9]. Some inherited diseases such as nevoid basal cell carcinoma syndrome (NBCCS) or Gorlin-Goltz syndrome, xeroderma pigmentosum, Bazex-Dupré-Christol syndrome, Rombo syndrome, and oculocutaneous albinism (OCA) carry a great risk for developing BCC at an early age [10, 11]. Specific gene polymorphisms in regions responsible for pigmentary traits, such as melanocortin-1 receptor (MC1R), the human homolog of agouti-signaling protein (ASIP), and tyrosinase (TYR), are additionally associated with an increased risk for BCC [12].

Pathogenetically, UVR induces mutations in several tumor suppressor genes and proto-oncogenes that consequently lead to BCC formation [13, 14]. Mutations in genes causing hyperactivation of the hedgehog (HH) protein family pathway, including PTCH1 receptor, SMO signal transducer, and GLI transcription factors, are strongly associated with BCC development [15, 16]. Furthermore, the TP53 tumor suppressor gene is also linked to BCC formation. The PTCH1 and TP53 are considered UV signature mutations due to the strong association with UVRinduced mutagenesis [13, 16].

Almost 70% of BCCs arise on the face and 15% on the trunk, while they rarely develop in the genital area [17]. The diagnosis of BCC is based upon clinical examination and dermatoscopy findings and finally confirmed by histopathological analysis. Since dermatoscopic features of BCC strongly assist the clinical diagnosis of BCC, clinicians must be familiar with typical dermatoscopic findings of various subtypes of BCC [17–19].

#### **2. Dermatoscopy of basal cell carcinoma**

*Dermatoscopy or epiluminescence microscopy* is a widely used tool that increases BCC detection accuracy and distinguishes BCC subtypes. Dermatoscopy features of BCC are classified into three main categories: vascular, pigment-related, and non-vascular/non-pigment-related. Vascular structures include arborizing vessels and short fine telangiectasias. Pigment-related structures consist of maple-leaf-like areas, spoke-wheel areas, multiple blue-gray globules (ovoid nests), in-focus dots (peppering/buckshot scatter), and concentric structures. Structures such as ulcerations, multiple minor erosions, shiny white blotches and strands, red structureless areas, and multiple aggregated yellow-white globules are classified as non-vascular/ non-pigmented structures [20].

The most significant vascular dermatoscopic feature is arborizing vessels. More than three decades ago, arborizing vessels were described as the main feature

#### *Dermatoscopic Features of Basal Cell Carcinoma DOI: http://dx.doi.org/10.5772/intechopen.100390*

of BCC, with high diagnostic accuracy and predictive value of over 90% [21]. However, arborizing vessels are not limited to BCC but to any fast-growing lesions such as cysts and tumors, including benign skin tumors.

Various attempts to categorize dermatoscopic features for particular BCC subtypes have been described. Most of the studies focus on the vascular pattern in different forms of BCC. As mentioned before, besides the role in diagnosing BCC, dermatoscopy is of great value in management strategy, evaluation of response to non-ablative therapies, and margin detection before surgical excision. Regarding the management strategy of treatment, the first step is to distinguish between superficial and non-superficial BCC as it determines further management decision, with nonsurgical treatments considered the first-line option for sBCC, while surgical excision being the standard for nodular BCC (nBCC) and Mohs micrographic surgery representing optimal choice for more invasive infiltrative forms of BCC [22, 23]. Superficial BCC is characterized by an optimal response to non-ablative therapies, such as imiquimod and photodynamic therapy (PDT). The authors Urech et al. reveal that dermatoscopic findings of erosions or ulcerations strongly predict a favorable response to imiquimod [24]. The pigment-related structures can act as a competitive light-absorbing factor, significantly reducing the response rate of the tumor to PDT. This observation leads to the exclusion of PDT as a treatment option in the presence of pigmented features [25]. In monitoring the outcome of non-ablative therapeutic modalities, dermatoscopic disappearance of pigmented structures, ulceration, and arborizing telangiectasias are indicators of complete tumor clearance.

Further monitoring is recommended to recognize early post-treatment reappearance of BCC-specific structures. However, the detection of white or red structureless areas and superficial fine telangiectasia does not provide explicit information on the possible presence of residual disease since these features might also appear as a result of treatment-induced skin atrophy [26].

In the non-superficial BCC, dermatoscopy is used in presurgical excision margins marking since it can detect a sub-clinical tumor expansion by revealing disease-related features in peripheral areas of clinically healthy skin.

#### **3. Dermatoscopy of various BCC subtypes**

#### **3.1 Dermatoscopy of nodular basal cell carcinoma**

Nodular BCC clinically manifests as a flesh-colored papule or nodule with a smooth surface typically located in the face region (**Figure 1A**–**C**). This subtype of BCCs is the most common and comprises approximately 60–80% of all cases of BCCs [1, 22, 27]. NBCCs usually have a pearly appearance and visible arborizing telangiectasias, while their border is raised compared to the central part of the lesion. This elevated rolled border is one of the critical clues to diagnosis. Additional clinical feature of nodular BCC is ulceration, hence the terms "rodent ulcer" or "phagedenic ulcer" for describing the ulcerating forms of nBCC. In contrast to sBCC, which often emerges on the trunk, nBCCs usually arise in the head and neck area, especially on the cheeks, nose, nasolabial folds, forehead, and eyelids, although they may develop in any hair-bearing area of the skin [1, 2, 22, 28]. The clinical differential diagnosis of non-ulcerated nBCC lesions includes adnexal neoplasms, fibrous papules, intradermal melanocytic nevi, amelanotic melanoma, sarcoidosis, cutaneous tuberculosis, and foreign body granulomas. Regarding ulcerating nBCC, squamous cell carcinoma (SCC) and keratoacanthomas are potential differential diagnoses [29].

NBCC is considered low-risk BCC; hence, standard surgical excision with 4-mm clinical margins with postoperative margin evaluation or electrodessication and

#### **Figure 1.**

*(A) Left: nodular BCC clinically presented as a pink-colored nodule with a smooth surface. Right: dermatoscopy revealed small arborizing vessels (black arrows), blue-gray globules (circle), and scale due to ulceration (red arrow). (B) Left: nodular BCC may clinically manifest as a growing pink nodule. Right: the hallmark of nodular BCC is arborizing vessels. Be careful, vessels like this may blanch out if you press down hard on the lesion. (C) Left: skin-colored papule on the nose of the patient. Right: arborizing vessels identifiable as larger bright red stem vessels that branch into thinner branches (arrows) and gray-brown ovoid nests (square) are the most distinguishable features of nodular BCC.*

curettage (EDC) are the two available treatment options according to the National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology (NCCN Guidelines). EDC is an alternative therapeutic modality for patients who may not tolerate surgery or prefer this non-surgical treatment option [23].

Dermatoscopy findings of nBCC include arborizing vessels, large blue-gray ovoid nests, multiple blue-gray dots/globules, and ulcerations (**Figure 1A**–**C**). Among the latter, classical arborizing vessels are the most distinguishable feature of nodular BCC (**Figure 1A**–**C**), easily identifiable as larger bright red stem vessels that branch into thinner branches [28]. Arborizing vessels correspond to dilated tumor vessels in the superficial dermis. Although the pigmentation features are the hallmark of pigmented BCC, they may be present in nodular BCC as well.

*Dermatoscopic Features of Basal Cell Carcinoma DOI: http://dx.doi.org/10.5772/intechopen.100390*

The most common pigmentation feature of non-sBCC is blue-gray ovoid nests (**Figure 1A** and **C**). Blue-gray ovoid nests are pigmented structures that histopathologically represent pigmented tumor nests invading the dermis. It is worth noting that nBCCs generally appear more pigmented in contrast to sBCCs. In nBCCs, blue-gray pigmentation usually arises in the center of the lesion, whereas maple leaf-like areas, spoke-wheel areas, and concentric structures are closer to the peripheral part of the lesion [30]. Ulcerations are structureless, red to blackred areas in parts of epidermal loss (**Figure 1A**). In some cases, nBCC can even present with shiny white areas and rainbow patterns that occur when the polarized light illuminates vascular structures of the tumor. Further dermatoscopic findings of nBCC include milia-like cysts and multiple aggregated yellow-white globules [31].

Histopathology of nBCC consists of large, round islands of basaloid keratinocytes that extend from the epidermis to the dermis. The nuclei form palisades at the periphery of the lesions, in addition to a lack of central nuclear organization. In some larger tumor islands, necrosis leads to the development of cystic spaces. As a result of ulceration, an adjacent inflammatory infiltrate develops. Additionally, mucin pools may form in cystic or nodulocystic BCCs [32, 33].

In conclusion, the most specific dermatoscopic features of nodular BCC are arborizing vessels together with ulcerations, while some nodular BCCs additionally present with pigmented structures such as blue-gray ovoid nests. The surgery remains the cornerstone of the therapy of nBCC.

#### **3.2 Dermatoscopy of superficial basal cell carcinoma**

The superficial basal cell carcinoma clinically presents as well-circumscribed slightly scaly, shiny, red- to pink-colored non-firm macule, patch, or thin plaque (**Figure 2A** and **B**). The diameter of the tumor can range from a few millimeters to several centimeters. Additionally, the pigmented forms of sBCC may have a variable degree of spotty brown to black pigmentation (**Figure 2C** and **D**). Larger sBCC may also exhibit atrophic areas of hypopigmentation [1]. The central part of sBCC often appears atrophic in contrast to the pearly elevated border. The sBCC is locally destructive as it grows gradually and horizontally over time, reaching several centimeters in diameter if not treated. Induration, ulceration, and nodule all rarely appear as a result of the deeper invasion [2].

SBCC is the second most common subtype of BCC developing in approximately 15% of all BCCs. The predilection sites for sBCCs are the trunk and extremities. Often multiple sBCC may occur in one individual [22]. It is important to distinguish sBCC from other BCCs because of the different treatment strategies available for this entity. Currently, depending on the individual clinical presentation, standard surgical excision with postoperative margin evaluation or electrodessication and curettage (EDC) are the treatments of choice for low-risk sBCC, while topical 5-fluorouracil (5-FU) and 5% imiquimod are second-line treatment modalities [23, 34]. The differential diagnosis for sBCC includes actinic keratosis, Bowen's disease, and solitary lichenoid keratosis, in addition to inflammatory diseases such as nummular eczema, psoriasis, and cutaneous lupus erythematosus. Regarding histopathology, sBCC is marked by foci of palisading basaloid cells connecting in a net-like pattern and extending to the papillary dermis [18, 29].

The diagnosis of sBCC is based upon typical clinical features together with dermatoscopic findings and histopathological analysis. Dermatoscopy facilitates the differentiation of sBCC from other BCCs. The main dermatoscopic features of superficial BCC are maple-leaf-like areas, short fine superficial telangiectasias, shiny white-red structureless areas, concentric structures, spoke-wheel

#### **Figure 2.**

*(A) Left: superficial BCC clinically presented as well-circumscribed red- to pink-colored patch. Right: superficial BCC with short fine telangiectasias (arrows), small brown-gray dots (circles), and white-red structureless areas. (B) Left: well-circumscribed slight scaly, pink-colored macule. Right: arborizing vessels with ramification (black arrows) and multiple yellowish structureless areas representing small ulcerations covered with crust (red arrows). (C) Left: clinical presentation of superficial pigmented BCC. Right: the more experienced dermatoscopist will recognize the leaf-like structures (red circles) and concentric structures (white circles), structures corresponding to dermo-epidermal pigmentation. (D) Left: BCC exhibiting the various amounts of pigment and scale. Right: the dermatoscopic features of superficial BCC are maple leaf-like areas (red circles) and shiny white, red structureless areas (stars) throughout the lesion. In contrast, blue-gray ovoid nests (square) point to the diagnosis of an infiltrative variant of BCC.*

areas, and multiple small erosions [29, 35]. However, among the latter, the most positive predictive patterns of sBCC are multiple small erosions and maple leaflike areas together with short fine superficial telangiectasias (**Figure 2A** and **B**). Under dermatoscopy, short fine telangiectasias appear as fine vascular structures with length up to 1 mm, and only a few branches or commonly, no branching at all [35].

*Dermatoscopic Features of Basal Cell Carcinoma DOI: http://dx.doi.org/10.5772/intechopen.100390*

Recently dotted vessels have been described in sBCC located on lower extremities. As the dotted vessels are also a feature of Bowen disease, other features such as white shiny blotches/strands and superficial fine telangiectasia (SFT) should be considered when diagnosing sBCC in this anatomical region [36].

Furthermore, maple-leaf-like areas can be visualized as brown or gray/blue bulbous, leaf-like projections that never arise from the pigmented network or nearby confluent pigmented areas (**Figure 2C** and **D**). Histopathologically, they correspond to pigmented tumor islands that interconnect with lobular extensions. Multiple small erosions are frequently seen in sBCC and they appear as small brown-red to yellow crusts (**Figure 2B**) covering the areas of epidermal loss [30, 37].

Another finding in sBCC is spoke-wheel areas that resemble radial arrays that join at the darker center. They are consistent with tumor nests arising and connecting to the epidermis with finger-like projections and centrally located pigment. The areas of diffuse dermal and tumor fibrosis appear as opaque white to red-colored areas under dermatoscopy, and these are called white-red structureless areas, also familiar as milky-pink areas [38–40]. In addition, short white streaks also correspond to dermal fibrosis and are more commonly seen in sBCCs. Recently, a new dermatoscopic feature of sBCC named negative maple leaf-like areas (NMLLA) has been described. NMLLA are round non-pigmented well-defined bulbous projections similar to maple leaf-like areas on the white-colored background. These areas represent non-pigmented tumor nests at the dermo-epidermal junction and are usually associated with sBCC in the trunk region [41].

Furthermore, loosely arranged, well-defined focused fine brown-to-gray dots can also represent an unspecific feature of sBCC. They correlate with pigment deposition at the dermo-epidermal junction or melanophages in the papillary dermis [42].

Finally, negative predictive patterns of sBCC are ulceration, blue-gray ovoid nests, and arborizing vessels. These findings are suggestive of non-sBCCs subtypes. Among the listed criteria, blue-gray ovoid nests strongly support the diagnosis of infiltrative non-sBCC, which is especially relevant in differentiating clinically flat pigmented lesions. The blue-gray color results from pigment deposition deeper in the dermis, whereas brown pigment corresponds to melanin accumulation at the dermo-epidermal junction [39].

Some authors also suggest clinical subdivision of sBCC to patch, patch-toplaque, and plaque forms, as more palpable forms of BCC often exhibit dermatoscopic features of nodular BCC (nBCC) [43]. Another helpful finding, highly suggestive of sBCC is multiple small erosions in clinically flat lesions [44].

In brief, pigmented sBCC is defined by patterns corresponding to dermo-epidermal pigmentation, particularly maple leaf-like areas, spoke-wheel, and concentric structures, with the absence of blue-gray ovoid nests, arborizing vessels and ulceration [30]. By adhering to the latter, the diagnosis of sBCC can be made with the sensitivity of 81.9% and specificity of 81.8%. On the contrary, non-pigmented sBCC demonstrates superficial short fine telangiectasia, multiple small erosions, and translucent-to-opaque shiny white-red structureless areas. Dermatoscopy is a reliable method for distinguishing sBCC from other BCCs, and neoplastic and inflammatory disorders. Adding current dermatoscopy algorithms to clinical practice is of crucial importance for making the correct prebiopsy diagnosis [29, 35].

#### **3.3 Dermatoscopy of pigmented BCC**

Pigmented BCC is a variant of basal cell carcinoma that histologically exhibits increased melanin pigmentation. It is clinically presented as a nodular pigmented lesion or pigmented macule (**Figure 3A**–**E**). However, around 30% of BCCs that are clinically classified as non-pigmented reveal pigmented features under dermatoscopy; thus, the pigment-related structures may be found in all BCC subtypes, both superficially and non-superficially [30, 45]. Based

#### **Figure 3.**

*(A) Left: BCC clinically presented as firm pigmented papule. Right: pigmented basal cell carcinoma with arborizing vessels (arrows) and blue-gray ovoid nests (squares). (B) Left: clinical presentation of pigmented BCC. Right: this pigmented BCC shows the so-called maple leaf-like features (red circles). (C) Left: nodular pigmented BCC clinically presented as firm pigmented papule. Right: the heavily pigmented BCC with large blue-gray blotches (squares), blue-gray ovoid nests, and globules (circle) and arborizing vessels at the periphery of the lesion (arrow). (D) Left: clinical examination revealed small pigmented papule. Right: dermatoscopic picture of classic BCC with spoken wheel structures at the periphery (white circles) and fine arborizing telangiectasia (black arrows) in the middle of the lesion. (E) Left: unusual localization of BCC at labia major. Right: atypical presentation of nodular pigmented BCC with large blue-gray areas, ulceration covered by crust (red arrow), and milia-like cysts (triangles). This nodular BCC is hardly distinguishable from nodular melanoma.*

*Dermatoscopic Features of Basal Cell Carcinoma DOI: http://dx.doi.org/10.5772/intechopen.100390*

on histopathology correlation, features representing pigment at the dermoepidermal junction, such as maple-leaf-like areas, spoke-wheel areas, concentric structures, and focus dots, are in brown and appear more frequently in the superficial and infiltrating variant of BCC (**Figure 3B** and **D**). In contrast, features representing pigment in deeper layers of the dermis such as blue-gray ovoid nests and blue-gray globules are in blue or gray, and they are characteristic of the nodular subtype of BCC [37, 39, 45]. Multiple blue-gray globules are defined as numerous, loosely arranged round to oval, well-circumscribed structures similar but smaller than the ovoid nest (**Figure 3A**, **C**, and **E**). They histopathologically correlate with small tumor nests in the papillary or/and reticular dermis. On the other hand, large blue/gray ovoid nests are well-circumscribed, confluent, or near-confluent pigmented or elongated areas, more prominent than globules and not intimately connected to a pigmented tumor body (**Figure 3A**, **C**, and **E**). Regarding pathophysiology, they correspond to large tumor nests with pigment aggregates invading the dermis. Blue-gray blotches together with arborizing vessels represent pathognomonic findings of pigmented basal cell carcinoma. In-focus dot terms describe loosely arranged, well-defined small brown-gray dots, which appear sharply in focus. They correspond to small tumor aggregates in the superficial dermis or at the dermo-epidermal junction, although they may also represent free pigment deposits or melanophages at the junction. Maple leaflike areas are translucent brown-to-gray/blue peripheral bulbous extensions, mainly localized on the lesion's periphery that never arises from a pigmented network or adjacent confluent pigmented areas (**Figure 3B**). Histologically, they represent pigmented nests at the dermo-epidermal junction and in the superficial papillary dermis. Spoke-wheel areas are well-circumscribed radial projections, usually tan but sometimes blue or gray, meeting at an often darker (dark brown, black, or blue) central axis. They are a rare dermatoscopic feature, highly specific for BCC. Occasionally radial projections are not clearly defined, and they appear as globular structures with a darker center. In such cases, we call them concentric structures [37, 39, 45]. Heavily pigmented BCCs may show dermatoscopic features associated with melanocytic lesions, such as brown globules, a blue-white veil and peppering. It is not always possible to distinguish melanoma from BCC with dermatoscopy; therefore in that clinical setting, the correct management decision is more relevant than the diagnosis (**Figure 3E**).

#### **3.4 Dermatoscopy of infiltrative BCC**

Infiltrative BCC is an aggressive and recurrent BCC variant that constitutes 5–10% of the BCCs. It is a histologic variant characterized by invasive growth patterns with clinically indistinct borders. This subtype of BCC is more aggressive and requires wider surgical margins or Mohs surgery, in contrast to noninfiltrative variants such as nodular or superficial BCC, which are commonly treated with standard surgical excision. The most common dermatoscopy features that point to infiltrating growth of BCC are arborizing vessels, fine telangiectasia, shiny white structureless areas, ulceration, and whitish background. Vessels found in the infiltrative variant of BCC are more delicate and more scattered, with fewer branches than nodular subtypes. A pigmented subtype of infiltrative BCC can exhibit blue-gray ovoid nests or multiple blue-gray in-focus dots [28, 37]. The novel dermatoscopic feature linked to the infiltrative form of BCC is called a circumferential stellate pattern. It is defined as a geometric star-shaped pattern extending outward from the circumferential peripheral edge of the tumor and identified by white lines, vessels, or uneven skin surface morphology [46].

#### **3.5 Dermatoscopy of morpheaform/sclerodermiform BCC**

Morpheaform BCC is an uncommon variant of BCC in which tumor cells induce proliferation of fibroblasts within the dermis and an increased collagen deposition with sclerosis that clinically resembles a scar. The histologic extent often exceeds the clinical impression, leading to high recurrence rates after standard excision. Morheaform BCC displays dermatoscopic features at a later stage of development than other subtypes of BCCs [47]. Approximately 75% of tumors show a structureless hypopigmented porcelain area. Arborizing vessels are expected in morpheaform BCC, and they tend to have less evident branching. This subtype of BCC is rarely pigmented, but when they are, dermoscopy shows blue-gray ovoid nests [36]. If pink-white areas and fine arborizing vessels are seen in high-risk zones such as the nose, cheek, and periauricular area, clinician should consider a diagnosis of sclerodermiforme BCC.

#### **3.6 Dermatoscopy of fibroepithelial BCC**

Another uncommon variant of BCC is fibroepithelial BCC. Fibroepithelial BCC, also known as Pinkus tumor, clinically appears as erythematous, flesh-colored dome-shaped papule or plaque. Differential diagnoses include benign skin lesions such as dermal nevus, fibroma, seborrheic keratosis, and even malignant tumors such as amelanotic melanoma [48]. Dermatoscopy patterns seen in fibroepithelioma of Pinkus are fine arborizing vessels that have less evident ramification and are smaller in caliber in contrast to telangiectasia seen in other forms of BCC accompanied by white streaks under polarized dermatoscopy that are called crystalline structures similar to those in other forms of BCC. Pigmented variants show browngray structureless areas and blue-gray dots. Other common but unspecific findings are milia-like cysts and ulceration [48, 49].

#### **3.7 Dermatoscopy of basosquamous carcinoma**

Basosquamous carcinoma (BsC) is a controversial entity and has both diagnostic and therapeutic challenges. BsC combines histopathologic and dermoscopic characteristics of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) [1]. Like SCC, BsC is more locally invasive and aggressive, and metastasizes more often than other forms of BCC. Dermatoscopy features comprise both features of BCC and SCC. Therefore, besides arborizing vessels, ulceration, and blood crust that are standard features of BCC, BsC is characterized by keratin masses, surface scaling, and white structureless areas, and dermoscopic features are mainly seen in SCC [27].

#### **3.8 The dermatoscopic findings of other uncommon variants of BCC**

The nevoid BCC that typically develops in Gorlin-Goltz patients together with palmar pits may show blue-gray dots, globules, or nests and arborizing vessels at the periphery.

Micronodular basal cell carcinoma is a histopathological term that applies to BCCs in which smaller aggregations of basaloid cells infiltrate the dermis. They have destructive behavior, with subclinical spread and high rates of recurrence. Only a few studies have specifically analyzed dermatoscopic features of micronodular BCCs. The main features were truncated vessels and multiple blue-gray globules [42].

BCCs with a linear appearance are sporadic, sometimes seen in association with different histological subtypes. The most frequently affected sites are the periorbital area and the neck. The linear subtype of BCC may show any dermatoscopic features associated with BCC in general.

### **4. Conclusion**

Generally observing, classic arborizing vessels are typically found in a nodular variant of BCC, while short fine telangiectasia points forward the superficial form of BCC. Structures associated with pigment could be roughly divided into two categories based on melanin deposition. All dermatoscopic subtypes of BCC can exhibit various amounts of pigment. Maple leaf-like areas, spoke-wheel areas, concentric structures, and in-focus dots indicate the presence of melanin at the dermo-epidermal junction and are a feature of superficial BCC. On the other hand, large blue-gray ovoid nests and multiple blue-gray dots and globules correspond to melanin at the dermal level. They are the characteristic of a non-superficial variant of BCC. Spoke-wheel areas are a rare dermatoscopic feature, but they are highly particular for BCC. Ulceration represents a loss of epidermis and portion of the dermis and is primarily seen in nodular lesions. Ulcerated areas are frequently covered with coagulated blood or crust, sometimes making it difficult for further dermatoscopic review. Multiple small erosions are the characteristic of a superficial variant of BCC, and they are smaller than ulcerations and clinically observed as a yellowish crust.

Diagnosis of BCC is not established on a single dermatoscopy feature, but rather on the coexistence of several dermatoscopic features together with clinical presentation. Histopathology essentially yields the final and decisive diagnosis. Besides a prominent position in diagnosis, dermatoscopy holds an essential role in managing BCC, significantly improving the treatment and post-treatment outcome assessment, possessing a beneficial role during all the stages of BCC management.

#### **Author details**

Tina Zagar1 , Nika Hlaca1,2\* and Larisa Prpic-Massari1,2

1 Department of Dermatovenerology, Clinical Hospital Centre Rijeka, Rijeka, Croatia

2 Medical Faculty, University of Rijeka, Rijeka, Croatia

\*Address all correspondence to: nika.hlaca@uniri.hr

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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#### **Chapter 3**

## Dermatoscopy of Facial Non-Pigmented Actinic Keratosis and Intraepidermal Carcinoma

*Alise Balcere*

#### **Abstract**

Dermatoscopy improves the diagnostic accuracy of non-pigmented facial lesions, including actinic keratosis (AK) and intraepidermal carcinoma (IEC) and helps to differentiate them from common invasive malignancies such as basal cell carcinoma and invasive squamous cell carcinoma. The most common dermatoscopic features characterizing AK are background erythema/erythematous pseudonetwork, white follicular openings/targetoid hair follicles, surface scales, rosettes, fine, linear, wavy vessels, microerosions and sun-damaged surrounding skin. In comparison, the most common dermatoscopic features of IEC are background erythema, red starburst pattern, surface scale, dotted/glomerular vessels, hairpin vessels, microerosions/ulcerations and targetoid hair follicles. The practice of recognizing these features in dermatoscopic images is a useful tool in the armamentarium of a clinician examining skin lesions.

**Keywords:** actinic keratosis, erythematous facial lesions, squamous cell carcinoma in situ, bowenoid actinic keratosis

#### **1. Introduction**

Actinic keratosis (AK) and other forms of squamous cell carcinoma (SCC) in situ are among the most common lesions in dermatological practice and are primarily the result of cumulative UV damage. The clinical relevance of accurate diagnosis relies on several factors. Firstly, misdiagnosing an inflammatory disease as an AK would lead to unnecessary and possibly harmful usage of destructive therapies on benign lesions. Secondly, AK is commonly a lesion in a field of sun-damaged skin, and among other lesions associated with chronic sun damage, some small clinically indistinguishable carcinomas may rest. Moreover, AK, although a common lesion, might progress to invasive SCC with gradual changes that can be visualized under a dermatoscope [1]. Furthermore, studies have shown that most SCCs arise from or in close proximity to AK and that dermatoscopy aids in differentiation between AK and SCC [2, 3]. Therefore, dermatoscopy is a useful tool for a clinician examining non-pigmented facial lesions allowing to differentiate between them.

Several forms of in situ SCC that are united by atypical keratinocytes in the epidermis but vary clinically, dermatoscopically, and histopathologically have been recognized [4]. Actinic keratosis (AK) and intraepidermal carcinoma (IEC) are the two main types of SCC in situ affecting facial skin. Much less common forms

include arsenical keratosis, radiation keratosis (caused by ionizing radiation), and hydrocarbon keratosis, in which dermatoscopic differences have not been described [5]. The following chapter will provide an overview of the clinical and dermatoscopic features that characterize different forms of AK and IEC of the face, including the dermatoscopic progression model from AK to invasive SCC.

#### **2. Definition of actinic keratosis and intraepidermal carcinoma**

The differentiation between AK and IEC relies on their histopathologic characteristics.

AK is also called solar or senile keratosis, SCC in situ AK-type, or keratinocytic intraepidermal neoplasia and represents a common lesion on chronically sun-damaged skin of fair skinned individuals. Histopathologically, AK presents as atypia of basal keratinocytes with loss of polarization, crowding, and overlapping that can extend up to near full thickness atypia in advanced lesions [5–8].

IEC is an intraepithelial SCC exhibiting full-thickness cellular dysplasia [9]. However, other synonyms employed for extragenital full-thickness intraepidermal carcinoma are Bowen's disease, in situ SCC, cutaneous SCC in situ, and intraepithelial SCC [1]. It is noteworthy that in comparison with other types of SCC in situ, Bowen's disease has been defined as SCC in situ arising on sun-protected skin, without field damage and possibly without association with HPV, although previously suggested otherwise [10–12]. For the consistency of this chapter, the term "*intraepidermal carcinoma*" will be used to describe facial intraepithelial SCC exhibiting full-thickness cellular dysplasia.

#### **3. Diagnosing AK and IEC**

Actinic keratosis in the majority of cases can be diagnosed clinically. Nevertheless, the clinical description of an erythematous macule or patch with a superficial scale may correspond to many other skin lesions and dermatoses. Studies [13, 14] examining the diagnostic precision of clinically diagnosed AK have reported misdiagnosis rates of approximately 10%. The main biopsy diagnoses in cases of misdiagnosis were SCC in situ, SCC with superficial invasion, seborrheic keratosis, basal cell carcinoma, and other benign skin lesions and dermatoses such as subacute spongiotic dermatitis, rosacea, solar elastosis, scars and verrucae plana. Pivotal differential diagnosis of AK is invasive SCC that can mimic AK if presenting as an erythematous macule. It has been shown that 1.5% of clinically diagnosed AK lesions identified by board-certified dermatologist were SCCs with superficial invasion on histologic assessment [13]. In comparison, dermatoscopy improves the diagnostic accuracy of both AK and SCC. A recent systematic review and study by Huerta-Brogeras *et al*. showed sensitivity up to 98.7% and specificity up to 95% if AK is diagnosed with dermatoscopy [15, 16].

Diagnosis of IEC is based on clinical, dermatoscopic, and histopathologic features.

#### **3.1 Clinical features of AK and IEC**

The most frequent presentation of both AK and IEC is a variably erythematous scaly patch or slightly elevated plaque [17]. AK is either single or multiple, while IEC is usually a single lesion. In comparison with AK, IEC is often an indurated

*Dermatoscopy of Facial Non-Pigmented Actinic Keratosis and Intraepidermal Carcinoma DOI: http://dx.doi.org/10.5772/intechopen.98875*

lesion on palpation. Both lesions are asymptomatic in most of the cases, although some patients experience discomfort, such as burning, pain, bleeding, and pruritus [6]. It has been noted that pain can be equally present in both AK and IEC, but is more common in invasive SCC [18].

A broad and useful tool for clinical description of the thickness of AK is a classification by Olsen *et al*. [19]. In this classification:


However, this clinical classification cannot reliably predict the histological grade proposed by Roewert-Huber *et al*. that could justify the classical progression model of AK to invasive SCC through clinical thickening and histopathological upward extension of atypical keratinocytes before invasion. It has been shown that only 26% of Olsen grade 1 lesions were grade 1 on histopathology with atypical keratinocytes in the basal and suprabasal layers of the epidermis, 75% of Olsen grade 2 lesions were grade II on histopathology with atypical keratinocytes extending to the lower two-thirds of the epidermis and only 14% of Olsen grade 3 lesions had corresponding grade III on histopathology with atypical keratinocytes extending to more than two thirds of the full thickness of the epidermis [8, 20].

#### **3.2 Dermatoscopic features of AK and IEC**

For the description of dermatoscopic features of AK and IEC, both metaphoric and descriptive language can be used. Definitions of the main metaphoric and descriptive terms are given in **Table 1**.

Main dermatoscopic features of AK are depicted in **Table 2**. Main dermatoscopic features of IEC are depicted in **Table 3**.


#### **Table 1.**

*Standardized terms of common dermatoscopic features for AK and IEC [18, 21–23].*


#### **Table 2.**

*Dermatoscopic features of AK categorized in three groups according to their prevalence. The most common dermatoscopic findings – Features present in almost all to the majority of AKs. Less common, but possible findings – Present in some AKs, although more common and characteristic for other lesions. A rare finding – Sometimes present in AK, but a differential diagnosis is much more likely. Abbreviations: AK – Actinic keratosis; IEC – Intraepidermal carcinoma; KA - Keratoacanthoma; SCC – Squamous cell carcinoma; BCC – Basal cell carcinoma [1, 6, 15, 22–26].*

#### *3.2.1 Characteristics of specific features*

#### *3.2.1.1 Erythematous pseudonetwork*

Erythematous pseudonetwork can be defined as a marked pink-to-red background erythema formed by fine wavy telangiectatic vessels surrounding accentuated hair follicles [23]. It is one of the most common and characteristic findings of AK.

*Dermatoscopy of Facial Non-Pigmented Actinic Keratosis and Intraepidermal Carcinoma DOI: http://dx.doi.org/10.5772/intechopen.98875*


#### **Table 3.**

*Dermatoscopic features of IEC categorized in three groups according to their prevalence. The most common dermatoscopic findings – Features present in almost all to majority of IECs. Less common, but possible findings – Present in some IECs, although more common and characteristic for other lesions. A rare finding – Sometimes present in IEC, but a differential diagnosis is much more likely. Abbreviations: AK – Actinic keratosis; IEC – Intraepidermal carcinoma; KA - Keratoacanthoma; SCC – Squamous cell carcinoma; BCC – Basal cell carcinoma [1].*

#### *3.2.1.2 Targetoid hair follicles*

Targetoid hair follicles are formed by yellowish keratotic plugs within the hair follicles and surrounded by a whitish halo. This feature is particularly common for AK on the nose and hyperkeratotic AK [23].

#### *3.2.1.3 Strawberry pattern*

Strawberry pattern (**Figure 1**) is a composite appearance of reddish pseudonetwork and hair follicles. This pattern is present in up to 95% of AK [23].

#### *3.2.1.4 Surface scales*

Scales are one of the most common features of AK and correlate with hyperkeratosis and parakeratosis on histopathology [21]. The distribution is usually diffuse throughout the lesion, although some lesions can be partly scaly (**Figure 1**) and a central scale is common for hyperkeratotic lesions. The color of the scales varies from white to yellow and an accumulation of exogenous pigment has been reported [27].

#### **Figure 1.**

*Dermatoscopic image of an AK. White scales limiting visualization of the underlying structures are seen on the left side of the picture, while a typical strawberry pattern with erythematous pseudonetwork and targetoid hair follicles are seen on the right side.*

#### *3.2.1.5 Rosettes*

Rosettes are also named 4-dotted-clods in descriptive terminology. Rosettes are a clue for keratinizing neoplasms, although they can also be observed in several other conditions including basal cell carcinoma, melanoma, melanocytic nevus, dermatofibroma, scar, molluscum contagiosum, actinically damaged skin and cicatricial alopecia of lichen planopilaris [28]. The dermatopathological correlate of 4-dottedclods in AK is horizontally arranged alternating hyperkeratotic and parakeratotic corneal layers in the follicular infundibula associated with mild peri-follicular fibrosis [28]. It has also been proposed that smaller 4-dotted-clods are caused by the concentric horn in the follicle at the infundibular level, whereas larger ones are caused by concentric fibrosis around the follicle [29].

#### *3.2.1.6 Fine, linear, wavy vessels*

Focused linear wavy vessels surrounding the hair follicles was found in more than 80% of facial AKs in a study by Zalaudek *et al*. These peculiar linear, wavy vessels of facial AK clearly differ in morphology from the arborizing vessels of vessels of nodular basal, short fine telangiectatic vessels of superficial basal cell carcinoma, and regular hairpin vessels that are characteristic of seborrhoeic keratosis. Furthermore, wavy vessels typically encircle the hair follicles as single and uniform units, which contrasts with the irregularly sized and distributed linear irregular vessels that can be seen in amelanotic/hypomelanotic melanoma, areas of regression in melanoma, or invasive SCC [23].

#### *3.2.1.7 Microerosions*

Microerosions are small erosions on the surface of the lesion seen under a dermatoscope. Microerosions are twice as common in IEC in comparison with AK, but are also a common feature of superficial basal cell carcinoma [1].

*Dermatoscopy of Facial Non-Pigmented Actinic Keratosis and Intraepidermal Carcinoma DOI: http://dx.doi.org/10.5772/intechopen.98875*

#### *3.2.1.8 Shiny white streaks*

Shiny white streaks (SWS) are also known as chrysalis or crystalline structures by their metaphoric terms. Dermatoscopically, SWS are only visible in a polarized light dermatoscopy as white, perpendicular, few millimeters long lines. Histopathologically, SWS are caused by polarization of thickened hyaline fibrous bundles and therefore considered as a dermatoscopic sign of dermal fibrosis. Shiny white streaks have been reported in a variety of skin lesions, mainly dermatofibromas, scars, basal cell carcinomas, lichen planus like keratosis, invasive melanoma, melanoma metastasis and sometimes even solar lentigo and intradermal nevus. In addition, it has been reported that SWS might be less common in inflamed lesions [22, 25, 29–31].

#### *3.2.1.9 Sun damaged surrounding skin*

The importance of recognizing the features of the surrounding skin is based on several factors. First of all, AK quite commonly has a confluent solar lentigo on the border. Secondly, it has been hypothesized that humans focus on the lesion and not on the surrounding skin and therefore are outperformed by artificial intelligence in the precision of AK diagnosis. Moreover, teaching medical students to pay attention to chronic sun damage in the background improved the frequency of correct diagnoses of pigmented actinic keratoses from 32.5% to 47.3% [26]. In addition, lesions arising in field cancerization have a higher potential for malignant progression. The latter has been recognized in a new nomenclature of keratinocyte cancers by Conforti *et al.* According to the authors, all keratinocyte cancers should be classified in two groups - 'cSCC+field' for keratinocyte cancers arising in the presence of AK within the field of cancerization and 'cSCC-field' for keratinocyte cancers arising in the absence of AK or field cancerization [32].

#### *3.2.1.10 Red starburst pattern*

Red starburst pattern can be defined as radially arranged structureless red lines or hairpin vessels that surround a yellow to white structureless scaly center and that resemble an overall starburst appearance (**Figure 2**). Red starburst pattern is equally common in IEC and invasive SCC, and less common in AK [1].

#### *3.2.1.11 Dotted/glomerular vessels*

Dotted vessels are tiny red dots densely aligned next to each other [1]. Glomerular vessels are larger-caliber reddish dots formed by tortuous capillaries curled up into a ball and resembling the glomerular apparatus of the kidneys. Glomerular vessels are specific for Bowen's disease, if located in clusters and bowenoid AK, if distributed regularly. Glomerular vessels can also be present in stasis dermatitis, psoriasis, irritated seborrheic keratosis, superficial basal cell carcinoma and melanoma [33–35]. The combination of clustered dotted/glomerular vessels and hyperkeratosis has been previously shown to achieve a 98% diagnostic probability for IEC [1, 35].

#### *3.2.1.12 Hairpin vessels*

Hairpin vessels are vessels that double back on themselves and are seen as loops when they are oblique to the surface of the lesion. Hairpin vessels are a common feature of keratinizing tumors and are a hallmark of seborrheic keratosis in which

#### **Figure 2.**

*Dermatoscopic image of IEC presenting with red starburst appearance formed by red and white radially arranged lines and central pink structureless clods, yellow scales, and hemorrhagic crusts.*

they are usually regularly distributed and surrounded by a white halo. Hairpin vessels are a rare but possible finding in AK and a common finding in IEC and SCC. Hairpin vessels are associated with progression of IEC to invasive SCC and clinically thicker lesions. Positive predictive value of hairpin vessels for seborrheic keratosis is 70%, contrasting with only 13.3% for squamous cell carcinoma [1, 33].

#### *3.2.2 Variants of AK*

Apart from classical AK, other forms categorized histopathologically are hypertrophic, atrophic, bowenoid, acantholytic, pigmented, lichenoid, and proliferative variants, although in this grading system overlap of histologic subtypes may occur in a single lesion [36].

**Atrophic AK.** In this form, the lesion has an atrophic epidermis on histopathology [5]. According to one study, atrophic type AK more commonly presents with red pseudonetwork [37].

**Bowenoid AK** has a characteristic dermatoscopic feature of glomerular vessels regularly distributed along the lesion (**Figures 3** and **4**), thus differentiating it from Bowen's disease, whose vessels are irregularly distributed and grouped [6].

**Hyperkeratotic AK** presents with a nonspecific dermatoscopic pattern due to hyperkeratosis, which prevents visualization of the underlying structures [6]. In addition, it has been shown that the surface keratin of AK can accumulate exogenous pigmentation, particularly from broad spectrum sunscreens containing titanium dioxide. Such a specific feature of bright arctic-blue or greenish-blue color of AK on polarized light dermatoscopy has been described and named an "iceberg sign" [27].

**Lichenoid AK** clinically presents with pronounced erythema around the base of the lesion secondary to an underlying lichenoid infiltrate on histopathology [5]. Dermatoscopically, lichenoid AK might also present with a more intense erythematous background.

*Dermatoscopy of Facial Non-Pigmented Actinic Keratosis and Intraepidermal Carcinoma DOI: http://dx.doi.org/10.5772/intechopen.98875*

#### **Figure 3.**

*Dermatoscopic image of bowenoid AK. Dermatoscopically regularly distributed glomerular (upper left) and hairpin (right and lower part) vessels in addition to a central white scale are seen.*

#### **Figure 4.**

*Dermatoscopic image of bowenoid AK. Dermatoscopically regularly distributed dotted and glomerular vessels, white surface scales, yellow clods corresponding to hyperkeratosis (upper part), and few milia like cysts (lower left fragment) are seen.*

#### *Dermatoscopy*

### *3.2.3 Dermatoscopic–histopathologic correlations of AK*

Skilled observers can predict the histologic grade of AK with dermatoscopy, although in consensus with clinical features some studies do not find such correlations [37, 38]. The following dermatoscopic–histopathologic correlations have been previously proposed:


#### **Figure 5.**

*Histopathologically confirmed basosquamous carcinoma on the border of an AK. Dermatoscopically, two coalescent nodules, both with central ulceration and crust and peripheral dotted and hairpin vessels with white surrounding halo can be seen.*

*Dermatoscopy of Facial Non-Pigmented Actinic Keratosis and Intraepidermal Carcinoma DOI: http://dx.doi.org/10.5772/intechopen.98875*

#### **3.3 Dermatoscopic features of AK progressing to SCC**

Progression from AK to SCC might follow two pathways. The classical multistep pathway requires proliferation of atypical keratinocytes upwards through the entire epidermis and accumulation of further mutational and cellular events that lead to invasive growth [40]. Nevertheless, the differentiated pathway assumes that invasive SCC may directly arise from a proliferation of atypical basaloid cells of the epidermal basal layer without full-thickness atypia [41].

Dermatoscopic features suggesting progression of AK towards SCC are dotted/ glomerular vessels, hairpin vessels, white halos surrounding vessels, ulceration/ bleeding, white structureless areas, and white circles surrounding follicles [24]. Appearance of these additional dermatoscopic features is an important clue to perform a diagnostic biopsy even in long-standing AKs, as a great majority of SCCs are associated with preexisting AKs [3] (**Figure 5**).

#### **Figure 6.**

*A lesion on the lower part of the left cheek that clinically presented as an erythematous indurated papule 5 mm in diameter. Dermatoscopically white circles (throughout the lesion), white structureless area (lower part), rosettes (in periphery), and dotted vessels (on the lower part) can be seen. Histopathologically, the basal growth pattern showed filiform papillary elongation protruding into the upper dermal structures in length that exceeds the overlying epidermis.*

#### *3.3.1 Characteristics of specific features*

#### *3.3.1.1 White circles*

On the basis of dermatoscopic–histopathologic correlation, white circles correspond to acanthosis and hypergranulosis of the infundibular epidermis or hyperkeratosis of the infundibular epidermis associated with central keratin plugs [28, 42].

White circles (**Figure 6**) are a specific feature of SCCs and keratoacanthoma-like SCC (KA) and have been shown to be equally common in both and more frequently than in other raised nonpigmented lesions. Moreover, when SCC and KA-like SCC were contrasted with AK and Bowen's disease, the positive predictive value of white circles was 92% in favor of SCC and KA-like SCC [42]. Nevertheless, another study did not find a statistically significant difference between the prevalence of white circles in KA-like SCC and SCC, vs., AK and BD [28]. Other lesions with white circles described are basal cell carcinomas, Bowen's disease, seborrheic keratosis, lichen planus–like keratosis, lichen simplex chronicus, folliculitis, ulcer, chondrodermatitis nodularis helicis, and a dermal nevus [42].

#### **4. Conclusion**

Dermatoscopy is a useful tool for the differentiation of AK, IEC, and other non-pigmented facial lesions. The diagnosis is based on the combination of lesion specific factors such as background and follicular structures, vascular patterns, and surface characteristics in addition to information received from the surrounding skin.

#### **Author details**

Alise Balcere Department of Dermatology and Venereology, Riga Stradiņš University, Riga, Latvia

\*Address all correspondence to: alise.balcere@gmail.com

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Dermatoscopy of Facial Non-Pigmented Actinic Keratosis and Intraepidermal Carcinoma DOI: http://dx.doi.org/10.5772/intechopen.98875*

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## Section 3
