Primary T-cell lymphoma associated with tubulovillous adenoma of the rectum: report of a case.

We report what to our knowledge is the first documented case of "peripheral T-cell lymphoma-not otherwise specified" (PTCL-NOS) associated with a rectal adenoma. Colorectal lymphomas are relatively uncommon, but colorectal T-cell lymphomas are extremely rare. The patient was a 92-year-old woman, referred to our hospital for investigation of anal bleeding. Rectal examination revealed a 3-cm pedunculated polypoid mass 5 cm above the anal verge. We performed a transanal local excision, and histopathological examination revealed a tubulovillous adenoma, with the diffuse proliferation of large lymphoid cells mainly discernible in the mucus membrane lamina propria, with infiltration to the submucosal layer. Immunohistochemical examination of the lymphoid cells revealed positive staining for CD3, weak staining for CD4 and CD8, and negative staining for CD5, CD10, CD20, CD56, CD79a, TIA-1, and Granzyme B. The tumor was diagnosed as PTCL-NOS associated with rectal tubulovillous adenoma. The patient died 28 days after surgery, most probably of progression of the PTCL-NOS.