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. Summary 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.

Atypical cerebral MRI imaging findings in a patient with isolated neurosarcoidosis

“…For Leptomeningeal enhancement we can see it in the cases of Tuberculosis, Cryptococcus and Primary Angiitis of the Central Nervous System, rarely we can see it in granulomatosis with polyangiitis and IgG4-related disease causing pachymeningitis. Isolated enhancement is rare in cases of primary central nervous system lymphoma, but enhancement with mass lesions is common [6] .…”

Sarkoidose – Mechanismen und Bildgebung

“…Die Kontrastmittelanreicherungen in den T1-gewichteten Sequenzen korrelieren mit aktiven Entzündungsherden und können leptomeningeale Beteiligungen, Myelitiden und parenchymatöse Entzündungsherde darstellen. In den T2-gewichteten Sequenzen können chronische Läsionen und das Ausmaß der entzündlichen Schädigungen dargestellt werden [11].…”

Insights into neurosarcoidosis: an imaging perspective

“…These imaging appearances are practically indistinguishable from the leptomeningeal involvement seen in infections (tubercular and fungal), lymphoma, and primary angiitis of the CNS. Care must be exercised to differentiate leptomeningitis from normal blood vessels, haemorrhage, and melanin [ 8 ].…”

“…Orbital apex lesions can cause compressive neuropathy of multiple upper cranial nerves [ 20 ]. Neurosarcoidosis is one of the important causes of bilateral facial nerve palsy along with Lyme disease and Guillain-Barré syndrome ( Figure 1C ) [ 8 ]. Differentials to consider include perineural spread of tumour, carcinomatosis, and lymphoma [ 18 ].…”

“…On imaging, neurosarcoidosis mimics many infectious, neoplastic, demyelinating, and inflammatory diseases and hence can be a difficult definitive diagnosis to make [ 4 , 7 , 8 ].…”