Collision tumor of menningioma and non Hodgin malignant lymphoma of cerebellum H. Erdem * , A. K. Uzunlar, U. Yildirim, A. Sav, M. Dosoglu * Duzce University, Dept. of Pathology, Turkey Primary central nervous system lymphoma (PCNSL) constitutes a rare group of extranodal non-Hodgkin's lymphomas (NHLs), primarily of B cell origin, whose incidence has markedly increased in the last three decades. Immunodeficiency is the main risk factor, but the large majority of patients are immunocompetent. This report presents the case of a 71-year-old woman with a collision tumor of primary malignant lymphoma and meningioma in the cerebellum. Collision tumor of primary malignant lymphoma and meningioma have not been described in the literature. The morphological aspect is interesting with regard to the problem of collision tumors.