Neurosarcoidosis mimicry of MS: Clues from cases with CNS tissue diagnosis.

The clinical picture of neurosarcoidosis (NS) shares many aspects with multiple sclerosis (MS). I examine whether or not clinical measures can reliably distinguish NS mimicking MS from NS coexisting with MS, and the informative role biopsy and autopsy evidence may play in understanding these two disorders. Uniquely challenging, I explore the rare patients presenting with the differential of MS or acute disseminated encephalomyelitis (ADEM) versus NS, including MS or ADEM as an associated illness in patients with systemic sarcoidosis. In most but not all NS patients, red flags against a diagnosis of MS are strong enough to rule out this more common disorder. Biopsy and autopsy findings indicate a tendency of NS granulomatous changes in the CNS to involve the same deep white matter perivascular spaces as expected to occur in MS, and hence correlate with a tendency of NS involving white matter to produce classic MRI findings of MS. The spectrum of NS includes some cases limited to a single anatomical site, including sites classically involved in demyelinating CIS (optic nerve, brainstem, and transverse myelitis). Asymptomatic "non-specific" periventricular MRI changes are described in many studies as "MS-like". No biopsied or autopsied cases have yet proven associated classic pathological changes of MS in patients with NS.