Primary cutaneous lymphomas: applicability of current classification schemes (European Organization for Research and Treatment of Cancer, World Health Organization) based on clinicopathologic features observed in a large group of patients.

Classification of primary cutaneous lymphomas (PCLs) is the subject of ongoing controversy. Based on a series of 556 patients, the applicability of the European Organization for Research and Treatment of Cancer (EORTC) classification for PCLs was assessed and compared to the proposed World Health Organization (WHO) classification of hematologic malignancies. The large majority of patients could be properly classified according to the scheme proposed by the EORTC. Comparison of estimated 5-year survival for specific diagnostic categories of PCLs demonstrated nearly complete concordance of the present results with those of the EORTC study for most of the indolent cutaneous T-cell lymphomas and cutaneous B-cell lymphomas, whereas differences were found for mycosis fungoides-associated follicular mucinosis and Sezary syndrome. A few patients with newly described entities (CD8(+) epidermotropic cytotoxic T-cell lymphoma, primary cutaneous natural killer/T-cell lymphoma) could not be classified according to the EORTC scheme. Comparison of the EORTC with the WHO classification showed that the EORTC scheme allows a more precise categorization of the patients, especially for cutaneous B-cell lymphoma. In conclusion, the study confirmed that the EORTC classification allows a better management of patients with PCL. Small amendments to that classification should be carried out to account for recently described entities and to unify some of the diagnostic categories.