PMC6376542_01
Colonoscopy with biopsies for case 1. (a) Ulcers in the descending colon. (b) Ulcers in the sigmoid. (c) Mild congestion and edema in the rectum. (d) In contrast to the relatively mild endoscopic findings of the rectum, histologically the infiltration is marked by dense atypical lymphoid cells with loss of crypts. (e) Low power view of the rectal lymphomatous infiltrate. (f) Higher power view of (e). Immunohistochemically the tumor cells are positive for (g) CD8, (h) CD56, (i) with high Ki-67 index.
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A diagnosis of MEITL was thus rendered (Figure 1).
Esophagogastroduodenoscopy and biopsies of case 1. (a) Erosions in the gastric body. (b) Narrow band image of the gastric body. (c) Biopsy of the body mucosa showing marked atrophy. (d) High power view showing intraepithelial infiltrate by lymphomatous cells.
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A gastric body mucosa biopsy showed obscured fundic glands with intraepithelial infiltration by small- to medium-sized lymphoid cells (Figure 2).
PMC6376542_02
Histologic findings in repeated biopsies of case 2. Infiltration by atypical lymphoid cells in (a) stomach, (b) duodenum, and (c) rectum. (d) Higher power view of (c), showing intraepithelial infiltration by monotonous medium-sized lymphoid cells with pale cytoplasm. (e) Immunostain for CK20 highlighting lymphoepithelial lesion. In addition, the tumor cells are strongly positive for (f) CD3, (g) CD8, and (h) CD56.
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There is extensive intraepithelial and lamina propria infiltration of monotonous medium-sized lymphoid cells with pale cytoplasm, in both random colon biopsies and the sigmoid biopsies (Figure 3).