Primary diffuse large B-cell lymphoma of the uterus presenting solely as an endometrial polyp

We report a primary diffuse large B-cell lymphoma of endometrial polyp in a 44-year-old woman who presented with irregular vaginal spotting and was found to have a polyp protruding from the cervical os. Histology of the polyp showed an atypical diffuse infiltration by large, mononuclear cells within the stroma and between endometrial glands in one of the polypoid fragments. Immunohistochemistry and testing for immunoglobulin heavy chain gene rearrangement showed a B-cell lineage, consistent with diffuse large B-cell lymphoma. Staging procedures including detailed gynecology examination, body computed tomography scan, and bone marrow examination, as well as total hysterectomy, showed no evidence of lymphoma outside of the polyp. To our knowledge, this represents the first well-documented instance of primary lymphoma of the uterus presenting as an endometrial polyp. The differential diagnosis of endometrial biopsies containing an atypical lymphoid infiltrate should include the rather rare possibility of primary uterine lymphoma arising in an endometrial polyp. Immunohistochemistry and/or molecular analysis for antigen receptor gene rearrangements are critical in arriving at the correct diagnosis. © 2005 International Society of Gynecological Pathologists.