Concurrence of Multiple Sclerosis and Brain Tumors

INTRODUCTION Multiple sclerosis (MS) is a chronic demyelinating inflammatory disease of the central nervous system (CNS) with multifactorial pathogenesis that includes genetic and environmental factors. A primary brain tumor is a neoplasm developing from the cells of the brain. There is high heterogeneity of primary brain tumors (about 100 different types); however, most of them develop from the glial cells. Although several types of brain tumors have been widely described in association with MS (1–20), including astrocytoma (5, 9), oligodendroglioma (12, 17), and glioblastoma (3, 11, 14, 18), it is not clear whether their occurrence is accidental or consequent to causal events. Moreover, it is not completely defined if MS and brain tumors, when associated, have a different course. The true incidence of brain tumors in MS patients is difficult to define because the diagnosis of a brain tumor in MS patients may seem more frequent than in the general population due to frequent neuroimaging scans performed in these patients (21). At the same time, pseudotumoral MS lesions may resemble gliomas, and conversely, early stage gliomas may resemble MS. Brain tumors in MS patients may be diagnosed later or even postmortem (22), especially in patients with progressive MS, since the new symptoms may be attributed to the gradual clinical progression of MS rather than to the slow growing of tumor itself (23). A recent study reported that MS patients have a decreased overall cancer risk, but an increased risk for brain tumor (24). If immunosuppressive treatment for MS might promote cancerogenesis is still matter of debate, it is difficult to explain on this basis why MS patients have a decreased overall cancer risk and an increased risk only for brain and genitourinary tract tumors (24). A successive systematic analysis showed no increased or decreased risks for glioma in MS patients, while an increased risk was found for meningioma, as a result of incidental findings (25). Moreover, several autoimmune diseases influence negatively the survival in glioma and meningioma, likely due to pre-existent disability or treatment limitations (25).