[Isospora belli infection in a patient with adult T-cell leukemia].

An adult T cell leukemia (ATL) accompanied with Isospora belli infection was described. A 65-year-old male was admitted to our hospital because of a two month history of watery diarrhea. On admission, physical examination showed slight pallor but no detectable superficial lymphadenopathies. Hepatosplenomegaly was not observed. Laboratory examination revealed a leukocyte count 5,500/microliters with 10% abnormal lymphoid cells. A majority of the abnormal lymphoid cells expressed both CD 4 and CD 8 antigens. The patient was diagnosed as chronic ATL, since anti-HTLV-1 antibody in his serum and monoclonal integration of HTLV-1 proviral DNA in his peripheral mononuclear cells were detected. Isospora belli was found in his feces thereafter, and trimethoprim/sulfamethoxazole was effective for diarrhea. In Japan, there have been only 9 reported cases of lymphoproliferative disorders (including five ATL patients) accompanied with Isospora belli infection. From the descriptions in those reports, these 9 cases might all be ATL patients.