Primary mesenteric tumor of adult T-cell leukemia/lymphoma: report of a case.

A rare case of primary mesenteric tumor of adult T-cell leukemia/lymphoma (ATLL) is reported. A 64-year-old man was admitted to our hospital after the diagnosis of a palpable ileocecal tumor. Although the serologic test for human T-cell lymphotrophic virus type I (HTLV-I) antibody was positive, neither ATLL cells in the peripheral blood nor systemic lymphadenopathy were observed. At laparotomy, the tumor was histopathologically revealed to be ATLL, and was also found to be restricted to the mesentery. An immunohistochemical examination of the tumor tissue using a specific monoclonal antibody was positive for CD2 and CD4, and negative for CD8. Proviral genome integration in the tumor cells was found by Southern blotting using a 32P-labeled HTLV-I probe with EcoRI and PstI digestion. Combination chemotherapy including cyclophosphamide, Adriamycin, vincristine, and prednisolone was begun postoperatively, but the patient did not respond to therapy. Up to now, only two cases of ATLL originating primarily in the abdominal cavity have been reported. These cases all demonstrate the need to consider the possibility of a primary ATLL mesenteric tumor without leukemic manifestation in the peripheral blood.