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.