Lymphomatosis cerebri showing transient spontaneous regression

We describe the case of a 35-year-old man who presented with a seizure. Brain magnetic resonance imaging (MRI) showed multiple white matter lesions in the cerebral hemispheres. His seizure was controllable with anti-epileptics, and he remained asymptomatic for the next 4 months with follow-up MRI showing transient spontaneous regression. However, he developed progressive decline in cognitive functions approximately a year after symptom onset. MRI showed recurrence of the white matter lesions and progression of brain atrophy. A brain biopsy established the pathological diagnosis of diffuse large B-cell lymphoma, and he was clinically diagnosed with lymphomatosis cerebri (LC). LC is a rare variant of primary central nervous system lymphoma characterized by diffuse infiltration of lymphomatous cells into the brain without forming a cohesive tumor mass. Although clinical and radiographic course is rapidly progressive in the great majority of patients with LC, transient spontaneous regression may occur, posing diagnostic challenges for physicians. This article is protected by copyright. All rights reserved.