Adult T-cell leukemia (ATL) is a special type of malignant clonal proliferative disease of the lymphoid system that occurs directly related to human T-cell leukemia virus I. (HTLV-I.) infection and occurs in adults, and its lesions mainly occur in peripheral blood lymphocytes, but can also invade the bone marrow. The disease was first proposed by Japanese scholar Gao Yueqing in 1976, and its clinical features are hepatitis, spleen, lymphadenopathy, skin infiltrates, interstitial pulmonary infiltrates and hypercalcemia. Following the detection of the disease in southwestern Japan, the presence of the disease has been reported in the United States, the Caribbean and other countries.