Introduction: Isolated neurosarcoidosis is a very rare disease, which makes up 5-15% of sarcoidosis cases. Hydrocephalus is a rare clinical feature with a prevalence of 6% among these patients. Considering neurosarcoidosis in the differential diagnosis of a unique parenchimal mass lesion could help in the early identification of this disease.

Case report: We report the case of a 27-year-old African man who developed with a sole intracranial mass lesion mimicking radiologically a glioma, which finally came out as an isolated neurosarcoidosis. Our patient presented with headache, blurred vision and papilledema. Imaging studies revealed a parenchymal mass lesion located in the right basal ganglia mimicking radiologically a glioma. No leptomeningeal involvement or other signs of systemic disease were found. A biopsy of the mass was performed. Histologically, a non-specific chronic inflammatory process with reactive gliosis was observed. Laboratory finfings and lumbar puncture were useful in ruling out other neurological disorders (tuberculosis, infectious-fungical diseases...). A second biopsy supported a diagnosis heavily reling on the exclusion of other non-caseating necrotizing cerebral granulomatosis. Three months later our patient developed with a communicating hydrocephalus without radiological meningeal spread. Hydrocephalus was successfully treated with a VP shunt after exclusion of a bacterial meningitis. On the other hand, the lesion did not completely regress despite of receiving intravenous corticosteroid treatment and our patient died five months later.

Discussion: There is a difficulty in diagnosis when isolated neurosarcoidosis appears. In addition, the low prevalence of the disease entails a not standardised medical treatment. Natural outcome is poor even when hydrocephalus is resolved.