Cutaneous lymphoma in Japan: A nationwide study of 1733 patients

Types of cutaneous lymphoma (CL) and their incidences may vary among geographic areas or ethnic groups. The present study aimed to investigate the incidences of various CL in Japan, using epidemiological data from a nationwide registration system for CL. Between 2007 and 2011, 1733 new patients with CL were registered from over 600 dermatological institutes in Japan. The 1733 patients registered included 1485 (85.7%) patients with mature T- and natural killer (NK)-cell neoplasms, 224 (12.9%) with B-cell neoplasms and 24 (1.4%) with blastic plasmacytoid dendritic cell neoplasm. Mycosis fungoides (MF) is the most common CL subtype in the present study (750 patients, 43.3%). The proportion of MF patients with early-stage disease was 73%, similar to that of previous studies from other cohorts. The incidence rates of adult T-cell leukemia/lymphoma and extranodal NK/T-cell lymphoma, nasal type were 16.7% and 2.0%, respectively, which may account for the higher incidence of mature T- and NK-cell neoplasms in Japan, as compared with that in the USA and Europe. A male predominance was observed in most types of CL, except for several CL subtypes such as subcutaneous panniculitis-like T-cell lymphoma

Distinct morphologic, phenotypic, and clinical-course characteristics of indolent peripheral T-cell lymphoma

Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) consists of a heterogeneous group of lymphomas. Patients. generally show an aggressive clinical course and very poor outcome. Although the 2008 World Health Organization classification of PTCL-NOS includes 3 variants, low-grade lymphoma is not Included. Of 277 PTCL-NOS cases recorded in our consultation files, we examined the clinicopathologic characteristics of 10 patients with T-cell lymphomas composed of small-sized cells with slight nuclear atypia. Eight patients showed extranodal involvement (5 patients, spleen; 3 patients, thyroid), and 5 patients were at clinical stage I or II. Histologically, all samples presented diffuse infiltrate of small lymphoid cells, with few mitotic figures. Immunohistologically, all samples were positive for CD3, and CD:20 Was detected in 5 samples. All samples showed a low Ki-67 labeling index (mean, 1.05%), and 7 samples were positive for central memory T-cell markers. Clonal T-cell receptor gamma chain and/or alpha-beta chain gene rearrangements were detected in all 10 patients. Five patients received chemotherapy, whereas for 3 patients, treatment consisted only of observation following surgical resection of the spleen or thyroid. Nine patients were alive at a median follow-up time of 19.5 months, whereas 1 patient died of an unrelated disease. The present study strongly indicates that T-cell lymphoma with small-sized lymphoma cells and a low Ki-67 labeling index is a distinct variant. Recognition of this novel lymphoma subtype, which should not be defined merely as PTCL-NOS, should be seriously considered

Epidemiology and secular trends of malignant lymphoma in Japan: Analysis of 9426 cases according to the World Health Organization classification

Abstract This study provides an overview of the epidemiology and secular trends of malignant lymphoma in Japan. Using data from clinics and hospitals throughout Japan, we analyzed 9426 cases of malignant lymphoma diagnosed in 2007‐2014. We show that the proportion of follicular lymphoma and methotrexate‐associated lymphoproliferative disorder increased during this time, as did the onset age for follicular lymphoma and diffuse large B‐cell lymphoma. Significant increases in onset age for follicular lymphoma and diffuse large B‐cell lymphoma were observed in both men and women (all P values <0.0001 except for P = 0.0448 for the latter disease in women). Further studies are required to determine the reasons for the higher proportion of and onset age for these lymphomas. Additionally, we believe that continued observation of these trends is necessary