Neurosarcoidosis: A Diagnostic Challenge

Neurosarcoidosis when presents with isolated cranial nerve involvement is a significant diagnostic challenge as it can mimic many other conditions like granulomatous infections, vasculitis, IgG4 disease and malignancy. Our patient is a 59 year old lady with symptoms of left sided facial pain, head ache and diplopia. Clinical examination revealed 5th and 6th cranial nerve involvement. MRI revealed enhancing smooth soft tissue lesion in pterygopalatine fossa, pterygomaxillary fissure with extension along V2 and V3. PET-CT revealed hypermetabolic lesion along left mandibular nerve in infratemporal fossa. Vasculitis panel also failed to aid in diagnosis. Biopsy done from the maxillary and mandibular nerve revealed non caseating granuloma which finally led to the diagnosis of Neurosarcoidosis. Presence of non caseasting granuloma in the histopathological examination with absence of infection and malignancy is diagnostic of Neurosarcoidosis. Patient was started on steroids and she improved clinically and symptomatically.