[A case of adult T-cell leukemia with a defective HTLV-I proviral DNA, in which the single T-cell clone appeared to have progressed from chronic phase to crisis].

A 39-year-old woman was first admitted to our hospital with increased white cell count on May, 1983. Physical examination showed only mild splenomegaly. Hematological examination revealed leukocytosis (14,600/microliters) with ATL cells (59%). Serum anti-HTLV-I antibody was positive. Examination of HTLV-I provirus in the abnormal T cells revealed the defective type. She was diagnosed as chronic type of ATL based on the clinical features. Cytogenetic study of the ATL cells revealed 47, xx, +4. For 12 months, she was followed without any therapy. WBC reduced to almost normal range and ATL cells decreased to 3 to 6% for 8 months. On May, 1985, she was readmitted to our hospital because of leukocytosis (32,200/microliters), and increased ATL cells (57%). She was diagnosed as crisis of ATL. Investigation of the proviral DNA and chromosome showed the same results as those of the chronic phase, indicating that ATL cells in both the chronic phase and the crisis phase originated from the same clone. She died after 3 months from massive diarrhea. Postmortem examination showed the extensive infiltration of leukemic cell in the small intestine.