Pseudotumoral forms of multiple sclerosis: report of 14 cases and review of the literature.

Background: The pseudotumoral form of multiple sclerosis (MS) is a rare condition with few descriptions in the literature. It supposes a diagnostic challenge especially when appearing at the onset of disease.

Methods: We retrospectively describe a case series of pseudotumoral MS patients that attended our hospital from 2004, analyzing demographic, clinical and radiological variables. We classified the lesions according to the recently proposed morphologic classification (infiltrative, megacystic, Baló or ring-like) and according to the contrast enhancement pattern (nodular, complete ring, incomplete ring and diffuse).

Results: Fourteen patients (11 female, 3 male), with a mean age of 35 years, were identified. All of them suffered from a relapsing-remitting form of MS. Eleven patients (78.57%) had symptomatic pseudotumoral lesions (PL), being the form of clinical presentation in the majority of those patients that were symptomatic (81.81%). Several patients presented atypical clinical manifestations such as cognitive impairment (21.42%) and epileptic seizures (14.28%). Full recovery was found in 53.84% of all symptomatic episodes. After a mean follow-up of 43 months, recurrent PL episodes were seldom observed (21.42%), the annualized relapse rate was 0.95 and the mean final Expanded Disability Status Scale score was 1.5. The majority of PLs were supratentorial, coexisted with typical demyelinating plaques and showed the ring-like morphology and the ring pattern of contrast enhancement. Three patients had more than one PL on the same scan, all of the lesions with similar morphology.

Conclusions: Our findings contribute to a better characterization of pseudotumoral forms of MS. However, larger studies are required to define this atypical entity more exactly.