Relative frequency of the different types of cutaneous T cell and natural killer cell lymphomas in Korea based on the proposed WHO classification and the EORTC classification

The R.E.A.L. classification was largely adopted recently by the proposed WHO classification. The usefulness of this classification in cutaneous T cell and natural killer (NK) cell lymphomas in Korea was evaluated compared to that of the European Organization for Research and Treatment of Cancer (EORTC) classification. Overall, 78 patients with cutaneous T cell and NK cell lymphomas were diagnosed in Asan Medical Center in the 1990's. The clinical records, slides of H&E and immunohistochemical stainings were reviewed. By the proposed WHO classification, mycosis fungoides (20 cases), lymphomatoid papulosis (13 cases), nasal type NK/T-cell lymphoma (10 cases), CD30+ anaplastic large cell lymphoma (8 cases), subcutaneous panniculitis-like T-cell lymphoma (6 cases), peripheral T-cell lymphoma, unspecified (3 cases), Sézary syndrome (1 case) and blastic NK cell lymphoma (1 case) comprised the primary cases. Secondary or undetermined cases included peripheral T-cell lymphoma, unspecified (10 cases), nasal type NK/T-cell lymphoma (5 cases), and angioimmunoblastic T-cell lymphoma (1 case). EORTC classification for cutaneous T cell and NK cell lymphomas did not include nasal and nasal type NK/T-cell lymphomas, unspecified non-pleomorphic T-cell lymphoma, undetermined cases among primary or secondary ones and some rare types of skin lymphomas which can be classified by WHO. The WHO classification is more useful for skin lymphomas in Korea since it encompassed all the various types of skin T cell and NK cell lymphomas in Korea.