UCHL1-positive extranodal lymphoma resembling multiple lymphomatous polyposis of the gastrointestinal tract.

Histopathologic and immunohistochemical studies were done on paraffin sections from a patient with alimentary tract lymphoma resembling multiple lymphomatous polyposis of the gastrointestinal tract (MLP). Diffuse, but not follicular, proliferation of medium-sized lymphoid cells was noted in the polypoid lesions of the alimentary tract, peripancreatic lymph nodes, spleen, liver, and bone marrow. These cells possessed a T-cell-related antigen (UCHL1), but were negative for the B-cell-related and myeloid cell-related antigens examined. Because neoplastic cells in MLP are usually of B-cell origin, the current case will provide important information on the relation between phenotypes and morphologic patterns of proliferation.