Monomorphic Epitheliotropic Intestinal T-cell Lymphoma of the Stomach: Two Case Reports and a Literature Review.

We describe the clinicopathologic and molecular features of 2 cases of gastric monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), which were first diagnosed from gastric biopsies, one was primary whereas the other was gastric involvement by MEITL. Both cases were older men with stomach ulcers. Case 1 was admitted for a hemorrhage in the upper digestive tract and case 2 for edema. Histology of both cases showed infiltrated monomorphic and medium-sized lymphocytes with lymphoid epithelial phenomenon. An inflammatory background and vascular hyperplasia were also observed likely due to the ulceration. Neoplastic cells expressed CD2, CD3, CD7, CD8, CD56, TIA-1, and MYC, not CD5, CD4, Granzyme B, CD20, CD30, TdT, or EBER. Both lymphomas showed TCRG gene rearrangement and c-MYC gains. Moreover, we first affirmed polysomy of chromosome 8 in case 2. For correct diagnosis of this rare tumor at the rare location, it is important that pathologists raise the possibility and exclude other differential diagnoses.