**4. Acquired causes of hair loss**

Common causes [12–15] of hair loss in children include telogen effluvium, tinea capitis, bacterial infections, traction alopecia, trichotillomania, and alopecia areata. In addition to the previous, other less common causes of hair loss can be seen including thyroid disorders and illnesses, such as systemic lupus erythematosus, diabetes mellitus, or iron deficiency anemia, malnutrition, structural abnormalities of the hair shaft that usually result in easy breakage and dry brittle hair. Hair types are influenced by ethnic groups that vary from region to region, and subsequently, this may reflect itself on the variation of common and uncommon causes of hair loss. This usually covers a broad differential diagnosis, and correct diagnosis, specific environmental and cultural factors may reflect itself on the prevalence of specific types of hair loss in children.

#### **4.1. Common causes**

There are five common types of hair loss in children: alopecia related to tinea capitis, alopecia areata, traction alopecia, telogen effluvium, and trichotillomania/trichotillosis.

#### *4.1.1. Tinea capitis*

Tinea capitis (ringworm of the scalp) is one of the more common causes of hair loss [16]. It is a disease caused by superficial fungal infection (superficial mycosis or dermatophytosis) of the skin of the scalp, with a propensity for attacking hair shafts and follicles. Tinea capitis is the most common pediatric dermatophyte infection worldwide [15].

Tinea capitis may present in several ways such as:


The potential of scarring and permanent alopecia is common in tinea capitis if left untreated (**Figure 6**).

Regarding the in vivo hair invasion in tinea capitis, there are three recognized types:


#### *4.1.2. Alopecia areata*

It is an autoimmune disease in which hair is lost from the scalp (**Figure 7**) or other hairy areas such as eyebrows, eyelashes, and other hairy areas in the body. It often results in bald spots on the scalp, especially in the first stages [17]. Rarely, the condition can spread to the entire scalp (alopecia totalis) or to the entire skin (alopecia universalis) (**Figure 8**). This type of alopecia is characterized by nonscarring alopecia (no fibrosis or inflammation), where the hair shafts are gone, but the hair follicles are preserved, making this type of alopecia reversible. Typically,

**Figure 4.** Tinea capitis in child presented as seborrheic dermatitis.

**Figure 5.** Tinea capitis in child with black dots presentation. There is no inflammation or no scales.

**Figure 6.** A child with scarring alopecia secondary to untreatable tinea capitis.

the patient first presented with small bald patches. The underlying skin is unscarred and looks superficially normal. These patches can take many shapes but are most usually round or oval. The disease may also go into remission for a time or may be permanent. It is common in children. Exclamation point hairs, narrower along the length of the strand closer to the base, may present and represent an activity of the disease.

#### *4.1.3. Traction alopecia*

**3.** Kerion—severely inflamed deep abscesses.

*phyton equinum*, and *Trichophyton verrucosum*.

thropophilic (e.g., *T. tonsurans*, *T. violaceum*).

**Figure 4.** Tinea capitis in child presented as seborrheic dermatitis.

and corresponding hair loss.

*4.1.2. Alopecia areata*

**5.** Carrier state with no symptoms and only mild scaling (*Trichophyton tonsurans*).

Regarding the in vivo hair invasion in tinea capitis, there are three recognized types:

The potential of scarring and permanent alopecia is common in tinea capitis if left untreated

**1.** Ectothrix invasion is characterized by the development of arthroconidia on the exterior of the hair shaft and usually fluoresces a bright greenish-yellow color under a Wood lamp ultraviolet light. Common agents include *Microsporum canis*, *Microsporum gypseum*, *Tricho-*

**2.** Endothrix invasion results from infection with *T. tonsurans*, *Trichophyton violaceum* and *Trichophyton soudanense*. The hair shaft is filled with fungal branches (hyphae) and spores and usually does not fluoresce with Woods light. All endothrix-producing agents are an-

**3.** Favus, usually caused by *Trichophyton schoenleinii*, produces favus-like crusts or scutula

It is an autoimmune disease in which hair is lost from the scalp (**Figure 7**) or other hairy areas such as eyebrows, eyelashes, and other hairy areas in the body. It often results in bald spots on the scalp, especially in the first stages [17]. Rarely, the condition can spread to the entire scalp (alopecia totalis) or to the entire skin (alopecia universalis) (**Figure 8**). This type of alopecia is characterized by nonscarring alopecia (no fibrosis or inflammation), where the hair shafts are gone, but the hair follicles are preserved, making this type of alopecia reversible. Typically,

**4.** Favus—yellow crusts and matted hair.

(**Figure 6**).

260 Hair and Scalp Disorders

Traction alopecia is a gradual hair loss, caused primarily by frequent and chronic hair pulling (**Figure 9**), and this is usually due to habit of hair styling [18]. It is also seen occasionally in longhaired people who use barrettes to keep hair out of their faces. There is a large variation

**Figure 7.** Small patch of alopecia areata; the skin is normal with no scales or no erythema.

**Figure 8.** Alopecia totalis with prominent exclamation marks.

in the pattern of clinical presentation of traction alopecia. If there is no suspicion of traction, it can be difficult to diagnose. Patients may present with (itching, redness, scaling, folliculitis or pustules, multiple short broken hairs, thinning, and hair loss). At a later stage, vellus hairs (fine short hairs) develop and terminal hair follicles reduce and are replaced by fibrotic fibrous tracts (scars).

#### *4.1.4. Telogen effluvium*

This is not an uncommon cause of hair loss in children; it refers to an abnormality of the normal hair cycle leading to excessive loss of telogen hair [19]. In telogen effluvium, many factors happen to interrupt the normal life cycle of hair and to throw many or all of the hairs into the telogen phase. After few weeks of the insult, partial or complete baldness appears. Frequent

**Figure 9.** Traction alopecia.

triggers include physiologic effluvium of the newborn, in this type; babies often lose their hair during the first 6 months. Similar to adult type of telogen effluvium, many different events can cause telogen effluvium, including extremely high fevers, severe previous illnesses, surgery under general anesthesia, severe prolonged emotional stress, severe injuries, and the use of certain prescription medication.

#### *4.1.5. Trichotollimenia*

in the pattern of clinical presentation of traction alopecia. If there is no suspicion of traction, it can be difficult to diagnose. Patients may present with (itching, redness, scaling, folliculitis or pustules, multiple short broken hairs, thinning, and hair loss). At a later stage, vellus hairs (fine short hairs) develop and terminal hair follicles reduce and are replaced by fibrotic fibrous

**Figure 7.** Small patch of alopecia areata; the skin is normal with no scales or no erythema.

This is not an uncommon cause of hair loss in children; it refers to an abnormality of the normal hair cycle leading to excessive loss of telogen hair [19]. In telogen effluvium, many factors happen to interrupt the normal life cycle of hair and to throw many or all of the hairs into the telogen phase. After few weeks of the insult, partial or complete baldness appears. Frequent

tracts (scars).

262 Hair and Scalp Disorders

*4.1.4. Telogen effluvium*

**Figure 8.** Alopecia totalis with prominent exclamation marks.

Trichotollimenia (**Figure 10**) is defined as a child or a teen that compulsively pulls out her hair and is thought to be related to obsessive-compulsive disorder [20]. These children have noticeable hair loss and often need treatment from a child psychiatrist and/or a child psychologist who specializes in trichotillomania. The hair loss is patchy and characterized by broken hairs of varying length. Patches are typically seen on the side of the child's dominant hand.

**Figure 10.** Trichotollimenia. The hair loss is patchy and characterized by broken hairs of varying length.

#### **4.2. Uncommon causes**

Rarer reasons for alopecia in children include pressure-induced alopecia, alopecia related to nutritional deficiency or toxic ingestion, and androgenetic alopecia. Other causes such as lichen planopliaris, chronic skin inflammation, universal pruritus, and severe dehydration.

### **5. Diagnosis of hair loss in children**

In an attempt to facilitate the diagnosis of hair loss in children, it is helpful to have a proper history from the parents; the key points in patient's history are age of onset of the patient; onset of hair loss: sudden or gradual; extent of alopecia: patchy or diffuse; associated symptoms; mental development; emotional triggers in the previous few months; and any accompanying complaints (e.g., fatigue, weight changes, and nail or skin abnormalities); past medical history (including chronic illnesses, surgeries, medication, autoimmune); family history of alopecia, autoimmune disease, dermatologic or psychiatric disorders; hair-grooming practices (chemicals, tight braiding) [21, 22]. Thorough examination of scalp as well as other hairbearing areas of the body is another key factor in diagnosis of hair loss. The examination should have the following components: type of hair loss: localized or diffuse; scarring or nonscarring; any hair shaft abnormalities; exclamation marks; hair texture and fragility; presence of pustules, scales, and erythema. Clinical examination of the entire body is necessary to evaluate hair loss, including teeth, skin, and mucous membranes.

The activity of hair shedding can be evaluated by hair pull test in which approximately 20 hairs are grasped and firmly tugged away from the scalp and then the number of extracted hairs is counted. Normally, fewer than three hairs per area should come out with each pull. If more than 10 hairs are obtained, the pull test is considered positive. The root of the plucked hair can be examined under a microscope to determine the phase of growth and is used to diagnose a defect of telogen, anagen, or systemic disease. Telogen hairs have tiny bulbs without sheaths at their roots. When the diagnosis of hair loss is unsure; a biopsy allows for differing between scarring and nonscarring forms. Skin biopsies are taken from areas of inflammation, usually around the border of the bald patch.

Further investigations are needed according to the suspected cases of tinea capitis, alopecia areata, or telogen effluvium. In tinea capitis, the diagnosis should be confirmed by microscopy and culture of skin scrapings (a potassium hydroxide preparation); woods lamp examination: as screening to detect flourescing species. When telogen effluvium is suspected, and there is no obvious trigger of telogen effluvium, blood tests are needed and include complete blood count; serum ferritin; serum zinc, antinuclear antibody; and thyroid function test.

Newly, dermoscope (trichoscope) [23, 24] is a noninvasive method of examining hair and scalp. It allows differential diagnosis of hair loss in most cases, especially in cases of hereditary hair shaft abnormalities. In the last few years, many studies have been published in this field. It may be performed with a manual dermoscope (×10 magnification) or a videodermoscope (up to ×1000 magnification). In particular, trichoscopy enhances the diagnosis of androgenetic alopecia, alopecia areata, telogen effluvium, trichotillomania, and congenital triangular alopecia, scarring alopecia, tinea capitis, and hair shaft disorders.
