CD4 and adult T-cell leukemia/lymphoma: Adult T cell leukemia/lymphoma (ATLL) is a peripheral CD4+ T cell malignancy caused by the human T-cell lymphotropic virus type I (HTLV-1) with a very high prevalence in tropical areas but only a few cases reported in China.[1,2] Diagnosis of ATLL requires histopathology and immunophenotyping of tumors, peripheral blood cytology, or morphology and immunophenotyping of peripheral blood and HTLV-1 serology.