Hydrocephalus associated to posterior fossa tumor-like sarcoidosis: A case report and literature review.

Background: Intracranial inflammatory pseudotumors (IIPT) are one of the differential diagnosis for the central nervous system (CNS) tumors. They represent a rare condition that may mimic clinically and radiologically intracranial tumors and induce their complications. Among their etiologies, neurosarcoidosis is one of the less known and less frequent. To the best of our knowledge, only two cases of posterior fossa IIPT have been reported in the literature. We present here the 3rd case related to a neurosarcoidosis. Case presentation: We report the case of a 55-year-old female patient who presented with an altered state of consciousness associated to severe intracranial hypertension syndrome for four months. Glasgow coma scale on admission was 14/15. Brain imaging revealed bilateral cerebellar micronodular meningeal enhancement regarding the mesencephalon and the pons, as well as a nodular lesion of the 4th ventricle causing a triventricular acute hydrocephalus. The patient had a ventriculo-peritoneal shunt with a favorable outcome. Afterwards, she underwent a salivary gland biopsy which confirmed the diagnosis of neurosarcoidosis.
Conclusion: Posterior fossa IIPT are very rare, mainly when located in the posterior fossa, leading to confusion with other pathologies. MRI has an important role in the diagnosis of these lesions, and the determination of their etiology. It shows other than the IIPT itself, many other signs such as leptomeningeal enhancement, nodular lesions or pituitary stalk thickening. These signs can orientate towards the diagnosis. Treatment may associate to symptomatic approach, corticosteroids. Surgical resection may be proposed when the diagnosis remains doubtful.