Case report: subependymal and leptomeningeal spread of systemic malignant lymphoma demonstrated by cranial computed tomography.

Secondary involvement of the central nervous system by systemic malignant lymphoma is uncommon, although increasingly recognized. Histologically perivascular, leptomeningeal, and subependymal infiltration by tumor cells is characteristic. Less frequently, single or multiple macroscopic masses resembling other metastatic deposits are found. A patient is presented in whom periventricular and leptomeningeal involvement by systemic histiocytic lymphoma produced prominent symmetric surface oriented enhancement on computed tomography following intravenous infusion of contrast medium. Differential diagnosis is discussed.