Adult T cell leukemia lymphoma in Chile. A clinico pathological and molecular study of 26 patients

Background: Adult T cell leukemia lymphoma is a lymphoproliferative syndrom e etiologically associated to human T cell lymphotropic virus type I. Aim: To describe the clinical and laboratory features of 26 Caucasian Chilean pa tients, with HTLV-I positive adult T-cell leukemia lymphoma (ATLL). Materia l and methods: Diagnostic criteria included clinical features, cell morphol ogy, immunophenotype, HTLV-I serology and/or DNA analysis by Southern blot or PCR. Results: According to the clinical presentation 12 cases had the ac ute ATLL form, 6 had a lymphoma, 4 the chronic form and 4 bad Smoldering AT LL. The median presentation age was 50 years , younger than the Japanese pa tients, but significantly older than patients om other South American count ries (eg Brasil, Jamaica, Colombia). The main clinical features: lymphadeno pathy, skin lesions and hepatosplenomegaly, were similar in frequency to th ose of patients from other countries, except for the high incidence of asso ciated neurological disease. Tropical Spastic Paraparests (TSP) in our seri es of ATLL, was seen in one third of the patients (8/26). A T-cell immunoph enotype was shown in all 26 cases and HTLV-I serology was positive in 25/26 patients. Molecular analysis on the seronegative patient showed clonal int egration of proviral HTLV-I DNA into the lymphocytes DNA, and thus he may h ave been a poor responder to the retroviral infection. Proviral DNA integra tion was also demonstrated in 15/16 patients being clonal in 10, polyclonal in 3 (all smoldering cases) and oligoclonal in one. Conclusions: ATLL in C hile has similar clinical and laboratory features es than the disease ill o ther parts of the world, except for a younger age than Japanese patients bu t older than those from other Latin American countries and a high incidence of patients with associated TSP. Detailed morphological and immunophenotyp ic analysis of the abnormal circulating lymphocytes, together with the docu mentation of HTLV-I by serology and/or DNA analysis are key tests for the i dentification of this disease.