Central nervous system involvement in CD4+/CD56+ hematodermic neoplasm: a report of two cases.

CD4+/CD56+ hematodermic neoplasm, formerly known as blastic NK-cell lymphoma, is an uncommon, aggressive non-Hodgkin's lymphoma with cutaneous, lymph node, and bone marrow involvement at presentation. The disease is characterized by early leukemic phase; however, central nervous system involvement is rarely reported. Herein we describe two cases of CD4+/CD56+ hematodermic neoplasm with meningeal manifestation. Microscopic analysis and flow cytometry of cerebrospinal fluid proved to be diagnostic; however, imaging studies were not informative. These observations call attention to the possibility of central nervous system involvement, which could be more common than expected previously. Authors recommend routine cerebrospinal fluid analysis and prophylactic intrathecal chemotherapy in patients with this highly aggressive disease.