Neurosarcoidosis: Diagnostic Challenges and Mimics A Review

Abstract

Purpose of review: Neurosarcoidosis is a rare manifestation of sarcoidosis that is challenging to diagnose. Biopsy confirmation of granulomas is not sufficient, as other granulomatous diseases can present similarly. This review is intended to guide the clinician in identifying key conditions to exclude prior to concluding a diagnosis of neurosarcoidosis.

Recent findings: Although new biomarkers are being studied, there are no reliable tests for neurosarcoidosis. Advances in serum testing and imaging have improved the diagnosis for key mimics of neurosarcoidosis in certain clinical scenarios, but biopsy remains an important method of differentiation. Key mimics of neurosarcoidosis in all cases include infections (tuberculosis, fungal), autoimmune disease (vasculitis, IgG4-related disease), and lymphoma. As neurosarcoidosis can affect any part of the nervous system, patients should have a unique differential diagnosis tailored to their clinical presentation. Although biopsy can assist with excluding mimics, diagnosis is ultimately clinical.

Keywords: Diagnosis; Granuloma; Mimics; Neurosarcoidosis.

Fig. 1

Selected MRI (T1 with contrast) imaging findings from patients with neurosarcoidosis. A Diffuse basilar leptomeningitis. B Longitudinally extensive myelitis in the cervical spine. C Pachymeningitis causing pachymeningeal enhancement. D Lumbar nerve roots showing enhancement. E Dorsal subpial leptomeningeal enhancement resulting in a “Trident Sign”