Medullomyoblastoma with calcification: a case report.

Medulloblastoma containing a striated muscle component is a rare embryonal cerebellar neoplasm, designated as medullomyoblastoma. We report here a case of medullomyoblastoma in a 9-year-old boy who developed signs of increased intracranial pressure and truncal ataxia. MRI disclosed a well-defined, egg-sized mass with heterogenous intermediate signal intensity in the cerebellar vermis, which compressed the 4th ventricle. The resected tumor consisted of hyperchromatic, undifferentiated neuroectodermal cells and desmin-positive myogenic cells with striation, compatible with medullomyoblastoma. MIB labeling index was 8% in undifferentiated cells but no labeling was seen in the myogenic cells. In addition, there were areas of calcification and psammoma bodies, which was a rare finding in this tumor.