A classification system for primitive neuroectodermal tumors (medulloblastoma) of the posterior fossa.

Tumors of the posterior fossa are described. Although the preoperative staging system of Chang and associates has proven prognostic relevance, a proposed new system may have even greater impact on prognosis because it considers the tumor burden postoperatively. This system (MAPS: metastasis, age, pathology, and surgery) incorporates age and pathologic characteristics into the staging system. The value of this proposed staging system, in particular, the impact of pathology, must be assessed in controlled trials.