Medulloblastoma and gliomatosis cerebri: rare brain tumors in multiple sclerosis patients.

The simultaneous appearance of both multiple sclerosis (MS) and central nervous system (CNS) tumors is relatively uncommon. Whether the co-existence of two diseases is due to chance alone or the result of a causal relationship is still a matter of debate. There is also controversy about the effect of long-term exposure of MS patients to immunomodulatory drugs on the incidence of cancer. This paper reports two cases of rare CNS tumors (i.e., medulloblastoma and gliomatosis cerebri) in adult MS patients. Our cases emphasize that when uncommon neurological features appear in patients with MS, brain magnetic resonance imaging (MRI) ought to be done and brain biopsy should be considered to exclude a concomitant CNS disorder. These procedures are essential for the differential diagnosis and early treatment.