The spectrum of cutaneous lymphomas in Japan: a study of 62 cases based on the World Health Organization Classification

BACKGROUND: The relative incidence of malignant lymphoma subtypes differs according to geographic location. This study investigated the epidemiology of cutaneous lymphoma subtypes in Japan and compared it with other countries. METHODS: Sixty-two patients with cutaneous lymphoma attending the Department of Dermatology, National Hospital Organization Hokkaido Cancer Center were reviewed. The World Health Organization classification of hematopoietic and lymphoid malignancies was adopted. RESULTS: Of the 62 patients, 31 had primary cutaneous lymphoma (PCL) and 31 had secondary cutaneous lymphoma (SCL). T- and natural killer (NK)-cell lymphoma accounted for 80% of PCL, of which, mycosis fungoides accounted for almost 35%. Of the 31 patients with secondary cutaneous lymphoma, 17 patients (54%) had T- and NK-cell lymphoma, including nine adult T-cell leukemia/lymphoma patients, and 14 patients (46%) had B-cell lymphoma, including 11 diffuse large B-cell lymphoma patients. The majority of patients with SCL and NK-cell lymphoma with primary or secondary skin lesions had a poor outcome. CONCLUSIONS: PCL in this study showed a similar incidence to that of other institutions in Japan, while also demonstrating different frequencies from that of other countries, suggesting that the relative frequency of different PCL subtypes differ according to geographical location, similar to previous reports of systemic malignant lymphoma.