The development of primary central nervous system B-cell lymphoma in multiple sclerosis.

When coupled with classical clinical signs and symptoms, magnetic resonance imaging can significantly aid in the diagnosis of multiple sclerosis (MS). However, the differential diagnosis of multiple sclerosis is large and, in the absence of pathognomonic clinical features, can be challenging to diagnose initially. Some conditions, such as primary central nervous system lymphoma (PCNSL) and progressive multifocal leukoencephalopathy (PML), can mimic clinically some of the symptoms prominent in multiple sclerosis. Early treatment with corticosteroids can dramatically improve patient symptoms in MS and PCNSL. We report a case of a man diagnosed with histologically confirmed relapsing remitting multiple sclerosis who subsequently developed histologically confirmed primary central nervous system lymphoma. Immunosuppressant therapy in the treatment of multiple sclerosis may be a potential catalyst in the development of central nervous system lymphoma. The course of his disease and treatment are presented and the current literature reviewed.