FAMILIAL HTLV-1-ASSOCIATED ADULT T-CELL LEUKEMIA LYMPHOMA/

Background. Adult T-cell leukemia-lymphoma (ATL) can occur in siblings infected with HTLV-1. Case reports. Two Caribbean siblings developed ATL a few years apart. One case has been reported previously. Both ind ividuals had peripheral lymph node T-cell lymphoma and a few atypical lymphocytes on blood smear. Lymphocytosis, bone marrow biopsy, abdomin al computed tomographic scanning, and chest radiography were normal. C lonal rearrangement of T-cell receptor was present in skin lesions for both patients and in the blood for one. HTLV-1 serology was positive. Clonal integration of HTLV-1 provirus was demonstrated in skin lesion s in one patient and in blood lymphocytes in the other. Chemotherapy, then interferon alpha, were unsuccessfull in the first patient. Topica l metchloretamine was partially effective for the second patient. Disc ussion. ATL in siblings is explained by mother-to-child transmission o f HTLV-1 infection during breastfeeding.