Ectopic glioneuronal tissue in the middle cranial fossa region. Report of four cases

Neuroglial ectopia of the vestibular nerve masquerading as a vestibular schwannoma: A case report

Neuroglial ectopia is a rare entity of undetermined clinical significance. Here, we report a unique case of neuroglial ectopia of the vestibular nerve. A 27-year-old pharmacy student with a previous radiological diagnosis of vestibular schwannoma presented to our clinic for surgical evaluation. Magnetic resonance imaging (MRI) of the brain revealed a 17-mm T1 hypo- to isointense, T2 iso- to hyperintense, poorly enhancing left cerebellopontine angle mass extending into the left internal auditory canal compatible by imaging with a vestibular schwannoma. The lesion was resected under MRI guidance. The frozen specimen came back as a benign hypocellular lesion. Histological assessment revealed a peripheral nerve engulfed by glial fibrillary acidic protein-positive, S-100-negative cells, suggestive of neuroglial ectopia. There was no evidence of schwannoma. The main concerns were benign neoplasm with potential for progression or sampling artifact. The patient had an uncomplicated hospital course. This case report demonstrates an unusual case of neuroglial ectopia of the vestibular nerve. The differential diagnoses for a poorly enhancing cerebellopontine angle mass should include neuroglial ectopia.

Ectopic cerebellar tissue in the occipital bone: a case report

BACKGROUND

Ectopic cerebellar tissue located distantly from the normal cerebellum is very rare, and its pathophysiology remains to be elucidated.

CASE PRESENTATION

We report an extremely rare case of intraosseous ectopic cerebellum detected incidentally at suboccipital craniotomy in a 46-year-old Japanese woman with hemifacial spasm. She had a small bone defect in the occipital bone, which contained a tiny area of soft tissue surrounded by cerebrospinal fluid connecting to the normal subarachnoid space through a dural opening. Histopathology demonstrated cerebellar cortex tissue consisting of molecular and granular cell layers.

CONCLUSIONS

This is the first report of glioneuronal ectopia within the skull bone separated from normal brain tissue, and it is important to distinguish this entity from other osteolytic lesions.