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.