PMC5420418_01
Endoscopic images. Esophagogastroduodenoscopy shows a solitary submucosal tumor in the duodenal second portion. The top of the tumor is slightly depressed, showing a reddish color on white light imaging (a, b) and a brownish color on narrow band imaging (c). Endoscopic ultrasonography reveals that the hypoechoic mass is mainly confined to the mucosal layer (d). A small cystic area is also seen (white arrow) (e).
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In addition, a solitary submucosal tumor approximately 10 mm in diameter was found in the second portion of the duodenum (Figure 1). Endoscopic ultrasonography revealed a hypoechoic mass mainly confined to the mucosal layer (Figure 1(d)). A small cystic area was also identified on ultrasonography (Figure 1(e)).
Hypotonic duodenography image. A submucosal tumor with bridging folds is seen in the inferior duodenal angle.
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Hypotonic duodenography showed a submucosal tumor with bridging folds in the inferior duodenal angle (Figure 2).
Esophagogastroduodenoscopy images during endoscopic mucosal resection. A duodenal tumor is seen after indigo carmine spraying (a). After injection of hyaluronic acid solution into the duodenal submucosa, the tumor is completely resected with a bipolar snare (b, c).
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Therefore, we performed endoscopic treatment rather than surgical resection (Figure 3).
Histopathological images. Proliferation of Brunner's glands is seen in the resected specimen (a: x2, b: x20). Gastric foveolar metaplasia is also identified (a: blue square, c: x10). Atypical cells with pleomorphic macronuclei with dense chromatin forming irregular glandular structure are found in the superficial layer (a: red square, d: x20). Hematoxylin and eosin staining.
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Pathological analysis of the resected specimen revealed proliferation of Brunner's glands (Figures 4(a) and 4(b)). Gastric foveolar metaplasia was also identified (Figure 4(a), blue square, and Figure 4(c)). Atypical cells with pleomorphic macronuclei containing dense chromatin forming an irregular glandular structure were identified towards the lumen in the superficial layer (Figure 4(a), red square, and Figure 4(d)).
Immunohistochemical images. Proliferated Brunner's glands are positive for MUC6 (a, white arrow) and negative for MUC5AC (b, white arrow). In contrast, most of the cells with gastric foveolar differentiation (a, black arrowhead; b, black arrowhead) and atypical cells (a, black arrow; b, black arrow) are positive for MUC5AC but are negative for MUC6. Both gastric foveolar metaplasia and atypical cells partly show dual positivity for MUC5AC and MUC6, particularly in the deeper layer (a, arrowhead; b, arrowhead). Some atypical cells showed relatively higher positivity for Ki-67 staining (c, hematoxylin and eosin staining, arrows).
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Immunohistochemical studies revealed that proliferated Brunner's glands were positive for MUC6 (Figure 5(a), white arrow) and negative for MUC5AC (Figure 5(b), white arrow). In contrast, most of the cells with gastric foveolar differentiation (Figures 5(a) and 5(b), arrowhead) and atypical cells (Figures 5(a) and 5(b), black arrow) were positive for MUC5AC but negative for MUC6. However, both gastric foveolar metaplasia and atypical cells partly showed dual positivity for MUC5AC and MUC6, particularly in the deeper layers (Figures 5(a) and 5(b), arrowhead). Some atypical cells showed relatively higher positivity for Ki-67 staining (Figure 5(c), arrows).