The purpose of this study was to evaluate whether subdivision of adult T-cell leukemia/lymphoma (ATL) on the basis of clinical types, skin involvement, histologic features, cell size, and proliferative index (PI) was clinically relevant. Skin lesions were present in 47 cases (67%). Five cases were classified as primary cutaneous tumoral (PCT) type not included in the Shimoyama classification and characterized by skin tumors and absence of systemic involvement, lymphocytosis, and hypercalcemia. Mortality was high (61/70 [87%]). The overall median survival time (MST) was 12 months. The following variables were adversely related to survival: acute, lymphoma, and PCT types; absence of skin lesions; large cells; and PI more than 18%. The longer MST observed in cases with skin lesions was probably due to prolonged survival of the smoldering type (58 months). The MST of the PCT type (21 months) was shorter than that of the smoldering type, confirming the importance of clearly defining these 2 types of ATL.