*3.3.3 Neuroendocrine tumors (NETs)*

NETs (also known as carcinoid tumors) are mostly asymptomatic tumors with endocrine cell origin. Mostly, they are discovered incidentally, but they can cause hemorrhage, abdominal pain or syndromes related to functional active substances

#### **Figure 3.**

*(A) Endoscopic appearance during cap-assisted resection of a duodenal NET. (B) Same lesion after resection. (C) Echoendoscopic appearance of the same duodenal NET (hypoechoic, well delineated).*

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*Endoscopic Ultrasound Assessment of the Duodenal Wall Lesions*

secreted by them. They are found along the GI tract, more often in the rectum or

Their endoscopic appearance is not characteristic, usually resembling a small polypoid lesion with normal overlaying mucosa. Endosonographically they are mostly hypoechoic or isoechoic, and arise from the second layer (mucosa), but can

The variety of histological types, sizes and location origins, combined with the risk of malignant transformation, illustrate the necessity to resect NETs. In principle, if the lesion is smaller than 1 cm and does not invade the muscularis propria, endoscopic resection is possible, otherwise surgical resection is recommended (**Figure 3**).

The upstream ducts are well recognized. Following the duodenal wall, especially the muscularis major papilla represents the opening into the duodenum of the common bile duct and pancreatic duct. The tumor of the papilla is very well visualized during EUS and the dilatation of the propria can differentiate small ampullary tumors that are limited to papilla from distal common bile duct tumors, which are situated beyond the muscularis propria layer (**Figure 4**).

The pancreatic accessory duct arrives in the duodenum at the level of the minor papilla. Sometimes EGD can confound it with an SET [4]. EUS examination can easily differentiate it from a tumor, as it is not part of the duodenal wall and the

Adenomas can appear in the duodenum, as anywhere else in the GI tract, sporadically or part of polyposis syndromes. They are premalignant lesions that usually necessitate removal. Peri-papillary location makes resection techniques more problematic, as simple resection can cause damage to the pancreatic or biliary ducts. Because they are mucosal lesions (second layer), solely EGD can be used for management. However, EUS can be necessary in certain circumstances, such as evaluating the depth of invasion if a malignancy is suspected, guiding the choice of treatment method (lesions extending to the submucosa need more advanced endoscopic resection techniques or surgery) and evaluating intraductal extension in

Malignant tumors of the duodenal wall are rare. Possible malignant tumors identified at this level include adenocarcinomas (from adenomas), malignant mesenchymal tumors (malignant GISTs), malignant NETs, lymphomas and metastases

These tumors share a common endosonographic characteristic by not respecting the layers of the duodenal wall (which are often lost) and often have adjacent

Leiomyomas are truly benign tumors arising from smooth muscle tissue, that is, the fourth layer and more rarely the second (muscularis mucosae). They are

*DOI: http://dx.doi.org/10.5772/intechopen.95927*

stomach, but also in the small intestine.

extend to the third layer (submucosa).

*3.3.4 Major and minor papilla lesions*

secondary duct is visible arriving at this level.

peri-papillary lesions (**Figure 5**).

from other cancers (very rare).

**3.4 Uncommon duodenal SETs**

*3.3.6 Malignant tumors*

lymphadenopathies.

*3.4.1 Leiomyomas*

*3.3.5 Adenomas*

**Figure 4.** *Endoscopic (left) and ultrasonographic (right) appearance of the papilla.*

#### *Endoscopic Ultrasound Assessment of the Duodenal Wall Lesions DOI: http://dx.doi.org/10.5772/intechopen.95927*

secreted by them. They are found along the GI tract, more often in the rectum or stomach, but also in the small intestine.

Their endoscopic appearance is not characteristic, usually resembling a small polypoid lesion with normal overlaying mucosa. Endosonographically they are mostly hypoechoic or isoechoic, and arise from the second layer (mucosa), but can extend to the third layer (submucosa).

The variety of histological types, sizes and location origins, combined with the risk of malignant transformation, illustrate the necessity to resect NETs. In principle, if the lesion is smaller than 1 cm and does not invade the muscularis propria, endoscopic resection is possible, otherwise surgical resection is recommended (**Figure 3**).

#### *3.3.4 Major and minor papilla lesions*

The upstream ducts are well recognized. Following the duodenal wall, especially the muscularis major papilla represents the opening into the duodenum of the common bile duct and pancreatic duct. The tumor of the papilla is very well visualized during EUS and the dilatation of the propria can differentiate small ampullary tumors that are limited to papilla from distal common bile duct tumors, which are situated beyond the muscularis propria layer (**Figure 4**).

The pancreatic accessory duct arrives in the duodenum at the level of the minor papilla. Sometimes EGD can confound it with an SET [4]. EUS examination can easily differentiate it from a tumor, as it is not part of the duodenal wall and the secondary duct is visible arriving at this level.

### *3.3.5 Adenomas*

*Endoscopy in Small Bowel Diseases*

*3.3.3 Neuroendocrine tumors (NETs)*

malignant GISTs.

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**Figure 4.**

**Figure 3.**

*(A) Endoscopic appearance during cap-assisted resection of a duodenal NET. (B) Same lesion after resection.* 

There is no specific study on contrast enhancement in case of duodenal SETs. A meta-analysis of gastric and esophageal SETs showed that contrast-enhanced endoscopic ultrasound is able to discriminate between GISTs and benign SETs with a pooled sensitivity of 89% and a specificity of 82%. For differentiating the malignant potential of GISTs, the sensitivity was 96% and the specificity was 53% [17]. An uptake of the contrast with the vascular hilum present suggests a leiomyoma, but a heterogenous vascularity suggests GISTs while irregular vessels suggest

NETs (also known as carcinoid tumors) are mostly asymptomatic tumors with endocrine cell origin. Mostly, they are discovered incidentally, but they can cause hemorrhage, abdominal pain or syndromes related to functional active substances

*(C) Echoendoscopic appearance of the same duodenal NET (hypoechoic, well delineated).*

*Endoscopic (left) and ultrasonographic (right) appearance of the papilla.*

Adenomas can appear in the duodenum, as anywhere else in the GI tract, sporadically or part of polyposis syndromes. They are premalignant lesions that usually necessitate removal. Peri-papillary location makes resection techniques more problematic, as simple resection can cause damage to the pancreatic or biliary ducts. Because they are mucosal lesions (second layer), solely EGD can be used for management. However, EUS can be necessary in certain circumstances, such as evaluating the depth of invasion if a malignancy is suspected, guiding the choice of treatment method (lesions extending to the submucosa need more advanced endoscopic resection techniques or surgery) and evaluating intraductal extension in peri-papillary lesions (**Figure 5**).

#### *3.3.6 Malignant tumors*

Malignant tumors of the duodenal wall are rare. Possible malignant tumors identified at this level include adenocarcinomas (from adenomas), malignant mesenchymal tumors (malignant GISTs), malignant NETs, lymphomas and metastases from other cancers (very rare).

These tumors share a common endosonographic characteristic by not respecting the layers of the duodenal wall (which are often lost) and often have adjacent lymphadenopathies.

### **3.4 Uncommon duodenal SETs**

#### *3.4.1 Leiomyomas*

Leiomyomas are truly benign tumors arising from smooth muscle tissue, that is, the fourth layer and more rarely the second (muscularis mucosae). They are

#### **Figure 5.**

*Top: Endoscopic view of duodenal adenoma. Bottom: Echoendoscopic appearance of the same adenomas. Enhanced vascularization is visible.*

mostly found in the esophagus, but they are described all over the GI tract. Their hypoechoic sonographic appearance makes them difficult to distinguish from other GIMTs. As such, EUS-FNA and histological examination are needed for a correct diagnosis. Resection is necessary only in case of symptoms.

### *3.4.2 Granular cell tumors*

Granular cell tumors (also known as schwannomas) are benign lesions that arise from the peripheral nerve sheath. They are hypoechoic, homogenous, well delineated and arise from the second or third layer of the duodenum (submucosa or muscularis propria). Even though the endosonographic appearance makes them hard to differentiate from GISTs or leiomyomas, schwannomas are much more rarely encountered in the GI tract. Tissue acquisition discriminates the diagnosis in such situations.

#### *3.4.3 Fibroid polyps*

Fibroid polyps are rare inflammatory tumors, sometimes found in the duodenum. They arise from the second or third layers and are usually hyperechoic and inhomogeneous [18].

#### *3.4.4 Hematomas*

Duodenal hematomas have been described, especially after abdominal trauma. However, some are spontaneous or arise from complications of endoscopic biopsies or other invasive maneuvers. They are usually diagnosed by CT scan or EGD. EUS is only needed in cases when the diagnosis is unclear, which is rare. They arise from the deep layers of the mucosa or submucosa (second or third layer). They have a different sonographic appearance depending on when they are evaluated. Initially, they have a heterogenous appearance in the first 24 hrs, which turns hyperechoic as more clots are formed and then slowly turns hypoechoic over the following weeks as it resorbs.

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*Endoscopic Ultrasound Assessment of the Duodenal Wall Lesions*

*DOI: http://dx.doi.org/10.5772/intechopen.95927*

*3.4.5 Gangliocytic paraganglioma*

*with no epitheliallining (HE-5X).*

**Figure 6.**

**3.5 Extrinsic compressions**

**4. EUS tissue acquisition**

(**Figures 6** and **7**).

hypoechoic SETs are hard to distinguish on EUS alone.

Gangliocytic paragangliomas are GI mesenchymal tumors, most often found in the second part of the duodenum near the ampulla of Vater [19]. They are formed by a varying mixture of spindle cells, epithelioid cells and ganglion cells (cells found also in other GIMTs). They are located in the third layer (submucosa) and are hypoechoic and homogenous. Histology usually offers the final diagnosis, as

*(A) Endoscopic view of external compression in the duodenum. (B) The echoendoscopic view shows an anechogenic lesion close to the transducer, a cyst. The pancreatic parenchima shows modifications consistent with chronic pancreatitis. (C) EUS-FNA - Paraduodenal cyst lined by inflammation and granulation tissue* 

In a series of 169 suspected SETs in the duodenum, which were referred to EUS, 12 were extrinsic compressions, with seven from the gallbladder and five from the pancreas [4]. EUS is very efficient in these cases, as it can identify the layers of the duodenum wall and correctly identify the duodenal compression as being extrinsic, as well as determine the cause of the compression and/or invasion

The sampling of SELs is unnecessary in case of lipoma or duplication cyst. However, some duodenal SETs (GISTs, neuroendocrine tumors) have malignant potential, so the size of the lesion is not a limitation for tissue acquisition. The

#### **Figure 6.**

*Endoscopy in Small Bowel Diseases*

mostly found in the esophagus, but they are described all over the GI tract. Their hypoechoic sonographic appearance makes them difficult to distinguish from other GIMTs. As such, EUS-FNA and histological examination are needed for a correct

*Top: Endoscopic view of duodenal adenoma. Bottom: Echoendoscopic appearance of the same adenomas.* 

Granular cell tumors (also known as schwannomas) are benign lesions that arise from the peripheral nerve sheath. They are hypoechoic, homogenous, well delineated and arise from the second or third layer of the duodenum (submucosa or muscularis propria). Even though the endosonographic appearance makes them hard to differentiate from GISTs or leiomyomas, schwannomas are much more rarely encountered in the GI tract. Tissue acquisition discriminates the diagnosis in

Fibroid polyps are rare inflammatory tumors, sometimes found in the duodenum. They arise from the second or third layers and are usually hyperechoic and

Duodenal hematomas have been described, especially after abdominal trauma. However, some are spontaneous or arise from complications of endoscopic biopsies or other invasive maneuvers. They are usually diagnosed by CT scan or EGD. EUS is only needed in cases when the diagnosis is unclear, which is rare. They arise from the deep layers of the mucosa or submucosa (second or third layer). They have a different sonographic appearance depending on when they are evaluated. Initially, they have a heterogenous appearance in the first 24 hrs, which turns hyperechoic as more clots are formed and then slowly turns hypoechoic over the following weeks as it resorbs.

diagnosis. Resection is necessary only in case of symptoms.

*3.4.2 Granular cell tumors*

*Enhanced vascularization is visible.*

such situations.

**Figure 5.**

*3.4.3 Fibroid polyps*

inhomogeneous [18].

*3.4.4 Hematomas*

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*(A) Endoscopic view of external compression in the duodenum. (B) The echoendoscopic view shows an anechogenic lesion close to the transducer, a cyst. The pancreatic parenchima shows modifications consistent with chronic pancreatitis. (C) EUS-FNA - Paraduodenal cyst lined by inflammation and granulation tissue with no epitheliallining (HE-5X).*

## *3.4.5 Gangliocytic paraganglioma*

Gangliocytic paragangliomas are GI mesenchymal tumors, most often found in the second part of the duodenum near the ampulla of Vater [19]. They are formed by a varying mixture of spindle cells, epithelioid cells and ganglion cells (cells found also in other GIMTs). They are located in the third layer (submucosa) and are hypoechoic and homogenous. Histology usually offers the final diagnosis, as hypoechoic SETs are hard to distinguish on EUS alone.

#### **3.5 Extrinsic compressions**

In a series of 169 suspected SETs in the duodenum, which were referred to EUS, 12 were extrinsic compressions, with seven from the gallbladder and five from the pancreas [4]. EUS is very efficient in these cases, as it can identify the layers of the duodenum wall and correctly identify the duodenal compression as being extrinsic, as well as determine the cause of the compression and/or invasion (**Figures 6** and **7**).

### **4. EUS tissue acquisition**

The sampling of SELs is unnecessary in case of lipoma or duplication cyst. However, some duodenal SETs (GISTs, neuroendocrine tumors) have malignant potential, so the size of the lesion is not a limitation for tissue acquisition. The

#### **Figure 7.**

*External invasion from a pancreatic head adenocarcinoma. (A) Endoscopic view: There are mucosal modifications visible (as opposed to 6A). (B) Echoendoscopic view confirms there is a pancreatic tumor. (C) EUS-FNA - foci of pancreatic ductal adenocarcinoma infiltrating submucosa of the duodenal wall (HE-5X).*

accuracy of EUS alone compared to the final histology (ESD or surgical specimen) varies between 44% and 66% and tissue acquisition is important for a correct diagnosis [20–22].

The sampling has to be performed using bite-to-bite biopsy followed by mucosal resection or submucosal resection in case of the lesions belonging to the second or third layers [11]. In case of the lesions originating from the fourth layer, the indication is for EUS-FNA or EUS–fine-needle biopsy (EUS-FNB) [23]. The unroofing method for sampling of fourth-layer lesions of gastric location was compared to EUS-FNB, but no difference for histologic core procurement was noted [24].

EUS sampling is preferred in case of lesions situated in the third or fourth layer, because the risk of bleeding is usually low and seeding into the peritoneum is avoided compared to percutaneous biopsy.

However, the use of EUS-FNA, especially with 22-guage and 25-guage needles, gave a diagnostic rate of 60% in a meta-analysis of 978 patients [25]. The main limitation is difficulty in assessing the architecture of the lesion sampled and the mitotic index. No influence of SET size on the diagnostic rate of FNA was found in a retrospective study of 112 patients [26]. The use of a pro-core needle compared to FNA needles does not improve the diagnostic rate [27–30]. However, only one study included SETs from

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**Author details**

**Conflict of interest**

**5. Conclusions**

Andrada Seicean1

Hospital, Cluj-Napoca, Romania

provided the original work is properly cited.

Romania

\*, Voicu Rednic2

The authors declare no conflict of interest.

interventions, EUS is crucial in lesions of the duodenal wall.

and Radu Seicean3

1 University of Medicine and Pharmacy "Iuliu Hațieganu," Regional Institute of

2 Regional Institute of Gastroenterology "Prof. Dr. Octavian Fodor," Cluj-Napoca,

3 University of Medicine and Pharmacy "Iuliu Hațieganu," County Emergency

© 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,

Gastroenterology "Prof. Dr. Octavian Fodor," Cluj-Napoca, Romania

\*Address all correspondence to: andradaseicean@gmail.com

*Endoscopic Ultrasound Assessment of the Duodenal Wall Lesions*

the duodenum [29]. The use of FNB gave better accuracy than EUS-FNA (88.03% vs. 77.19% [P = .030]) or EUS-FNA plus rapid on-site evaluation (ROSE) (87.25% vs. 68.00% [P = .024]), but no difference was noted compared to EUS-FNB plus ROSE [31]. In a meta-analysis comprising 10 studies that compared EUS-FNB and EUS-FNA, the diagnostic accuracy was greater in patients undergoing FNB sampling (OR, 4.10; 95% CI, 2.48–6.79; P < .0001) with a fewer number of passes and higher rate of optimal core procurement (OR, 3.27; 95% CI, 2.03–5.27; P < .0001) [32]. Because the distal duodenum can be difficult to reach, the sampling from this location is feasible

EUS is essential for evaluating duodenal lesions correctly and completely. EUS can identify if the lesion originates from the mucosa or the deeper layers of the duodenal wall, or if it is extrinsic. Other diagnostic methods lack the resolution to distinguish between them correctly. In addition, EUS can obtain tissue for histological analysis in all cases, as EGD-guided biopsies are not deep enough for SETs. Choice of treatment is also decided following EUS, as benign lesions do not need removal, potential malignant lesions (NETs, GISTs) can be followed or resected and malignant lesions can be resected endoscopically if EUS does not identify invasion of the deeper layers. Given all this, along with the complex surroundings of the duodenum, its thin walls and the difficult anatomical position for surgical

with thinner 25G needles, with a definitive diagnosis in 88% of patients.

*DOI: http://dx.doi.org/10.5772/intechopen.95927*

*Endoscopic Ultrasound Assessment of the Duodenal Wall Lesions DOI: http://dx.doi.org/10.5772/intechopen.95927*

the duodenum [29]. The use of FNB gave better accuracy than EUS-FNA (88.03% vs. 77.19% [P = .030]) or EUS-FNA plus rapid on-site evaluation (ROSE) (87.25% vs. 68.00% [P = .024]), but no difference was noted compared to EUS-FNB plus ROSE [31]. In a meta-analysis comprising 10 studies that compared EUS-FNB and EUS-FNA, the diagnostic accuracy was greater in patients undergoing FNB sampling (OR, 4.10; 95% CI, 2.48–6.79; P < .0001) with a fewer number of passes and higher rate of optimal core procurement (OR, 3.27; 95% CI, 2.03–5.27; P < .0001) [32]. Because the distal duodenum can be difficult to reach, the sampling from this location is feasible with thinner 25G needles, with a definitive diagnosis in 88% of patients.
