BackgroundIn East Asia, monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), previously known as type II enteropathy-associated T-cell lymphoma (EATL), occurs more frequently than type I EATL, and coeliac disease is rare.Case presentationHere we present four cases of MEITL in Japanese patients, including the endoscopic and pathological findings of their duodenal and colorectal lesions. Tumor specimens obtained from duodenal, intestinal, and colorectal biopsies in all four patients showed a diffuse intramucosal infiltration of small to/or medium-sized lymphoma cells and numerous atypical intraepithelial lymphocytes (IELs). These cells were immunohistologically positive for CD103, CD3, CD7, CD8, CD56, and T-cell intracellular antigen-1. Upper and lower gastrointestinal and antegrade double-balloon endoscopy revealed foci of edematous mucosa, with or without villous atrophy, in the non-neoplastic mucosa. Histological studies demonstrated duodenal and intestinal enteropathy-like lesions as well as microscopic (lymphocytic) proctocolitis with increased CD3- and CD8-positive and CD56-negative T-IELs in all four patients. The clinicopathological findings of the non-neoplastic lesions were similar to those characteristic of coeliac disease, suggesting that variants of coeliac disease may be present in the prodromal lesions of MEITL.ConclusionsOur study supports the need for random gastrointestinal biopsies to determine tumor spread, the features of MEITL in the particular patients, and the presence of prodromal non-neoplastic lesions.

We investigated the expression of the αEβ7 integrin (CD103)-intestinal homing receptor of T-intraepithelial lymphocytes (IELs) in 130 cases of adult T-cell leukemia/lymphoma (ATLL). We detected CD103 lymphoma cells in 55% (31/56) of mainly gastrointestinal (GI)-involved ATLL cases. Among them, lymphoma cells of 18 cases located in other involved organs had similar CD103 expression patterns. Histologically, we found (a) increased reactive IELs in non-neoplastic mucosal layers in 28% (5/18) of surgical and mucosal resection cases, (b) preserved epithelial glands, and (c) numerous small intraepithelial ATLL nests in involved lesions in 36 (69%) and 21 (40%), respectively, of the 52 examined cases. These 3 patterns were common in intestinal type II enteropathy-associated T-cell lymphoma but were rare in intestinal EBV nasal-type/like T/natural killer (NK)-cell lymphoma. We detected CD103 tumor cells in 41% (16/39) of lymph node-involved ATLL, in 31% (11/35) of skin-involved ATLL, in 68% (21/31) of type II CD4 enteropathy-associated T-cell lymphoma cases, in 36% (8/22) of primary gastric T/NK-cell lymphomas, and in 77% (7/9) of CD8 epidermotropic mycosis fungoides. CD103 ATLL prefers involving the GI tract over the skin (P<0.05). CD103 expression in GI-involved and/or total ATLL cases was significantly higher than in other 9 T/NK-cell lymphoma groups (P<0.05 or 0.01). Only ATLL cases were commonly CD103 in CD4 T/NK-cell lymphoma groups (P<0.05 or 0.01). Human T-lymphotropic virus-1-infected CD103 T-IELs and mucosal T cells may be important sources of ATLL.

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