In the past decades, there has been an increase in the incidence of malignancies, including polyneoplasms. Composite synchronous lymphoma characterized by the simultaneous development of several lymphoproliferative diseases occurs very rarely. This paper describes a case of development of 3 different lymphomas in the same patient. Aggressive T-cell lymphoma and indolent B-cell lymphoma are diagnosed during lifetime; primary central nervous system lymphoma is verified only by examination of autopsy material. Three different lymphomas could be identified by an integrated assessment of their clinical picture and by current diagnostic techniques, such as histology, immunohistochemistry, and molecular genetics.