Medulloblastoma metastatic to the marrow. Report of four cases and review of the literature.

Medulloblastoma is a malignant cerebellar tumor seen primarily in the pediatric age group that has a known ability to metastasize extraneurally. The skeleton is the most common site of extraneural metastases, but metastases to the bone marrow can also occur. Four cases of medulloblastoma metastatic to the marrow are reported. In addition, 31 cases from the medical literature are reviewed. Clinical features include bone tenderness, cytopenias and elevated serum alkaline phosphatase and lactic dehydrogenase levels. Skeletal involvement, especially of the pelvic bones, is frequently seen radiographically. Weight loss, soft tissue masses and a requirement for blood transfusion are also associated features. Marrow biopsy specimens are characterized by the presence of a small cell tumor often with fibrosis, necrosis and osteoblastic activity. The symptomatic response to chemotherapy is rapid, but chemotherapy resistance appears quickly. Only 1 in 4 cases diagnosed antemortem in this review lived for more than a year. We conclude that marrow aspiration and biopsy are indicated in the evaluation of patients with medulloblastoma and may serve to diagnose the cause of cytopenias, to verify extraneural spread and to provide prognostic information.