The applicability of the new WHO-EORTC classification of primary cutaneous lymphomas to a single referral center.

Recent years have witnessed differences between the World Health Organization (WHO) and the European Organization for Research and Treatment of Cancer (EORTC) classification systems of primary cutaneous lymphomas (PCLs). Recently, a joint WHO-EORTC classification system for PCLs has been reached. This study was performed to assess the applicability of this new classification to a single referral center. All new PCL cases, excluding mycosis fungoides and Sezary syndrome, who were referred from 1999 to 2005 were included. The histological, immunohistochemical stainings and molecular studies were reviewed, and additional stains were performed as needed. The cases were then reclassified according to the WHO-EORTC classifications. The clinical files were also studied, and the patients were followed up clinically. There were 43 new non-mycosis fungoides/Sezary syndrome PCLs, including 29 B-cell lymphomas of which 14 were follicle center lymphoma, 10 marginal zone lymphoma, 4 diffuse large-B-cell lymphoma, leg type, and 1 diffuse large-B-cell lymphoma, other. The 14 T-cell lymphomas included 5 cases of lymphomatoid papulosis, 2 CD30+ anaplastic large-cell lymphomas, 1 NK/T-cell lymphoma, and 6 peripheral T-cell lymphomas, unspecified. Of the 6 "unspecified" T-cell lymphomas, 3 were CD4+ small/medium-sized pleomorphic T-cell lymphoma, which is considered currently a provisional entity under the unspecified T-cell category. The remaining 3 cases could not be classified beyond the unspecified T-cell category, of which 2 cases had an aggressive course. The new WHO-EORTC classification is applicable to most non-mycosis fungoides/Sezary syndrome PCL cases, especially the B-cell lymphomas. However, there is still a substantial subset of T-cell PCLs which cannot be classified beyond the unspecified peripheral T-cell category, some of which may have an aggressive course.