A 76-year-old man with cognitive and neurological symptoms

A 76-year-old man presented with cognitive symptoms, followed by headache and weakness of the lower limbs and left arm. The clinical course was progressive but fluctuating. On magnetic resonance imaging (MRI), a contrast-enhancing lesion 1 cm in diameter was seen in the left temporal lobe. This lesion became attenuated and a new contrast-enhancing lesion 1 x 2 cm was seen in the left frontal lobe on a subsequent MRI. Following additional tests, treatment with corticosteroids for presumptive neurosarcoidosis was started, however, he soon expired. At autopsy, there was a tumor-like mass in the left frontal lobe. Pathologic evaluation revealed a primary T-cell lymphoma of the central nervous system (CNS). CNS T-cell lymphomas may be difficult to diagnose, even histologically, due to their frequent small cell morphology and lack of significant atypia.