Cerebellar medulloblastoma. An analysis of four cases of extraneural metastasis.

In four of 28 patients (14%) with medulloblastoma who were treated at the University of Wisconsin, Madison, over a 20-year period, extraneural metastases developed. In an effort to delineate the causal factors involved in extraneural metastases, salient features of patients with metastases and without metastases were compared. Suboccipital craniectomy, radiation therapy, and patient longevity were not well correlated with metastases. However, subarachnoid tumor spread was a consistent precursor. A ventriculoatrial shunt may have been a factor in one patient and a serious infection that preceded diffuse metastasis may have been a factor in another patient. Half of the patients with metastases were found to have the desmoplastic variety of medulloblastoma while only one of 24 patients without metastases had this tumor type.