Extraneural metastases of medulloblastoma: desmoplastic variants may have prolonged survival

Extraneural metastases from CNS medulloblastoma are rare and poorly described. The purpose of this study is to describe the clinical and radiological characteristics of a large single institution series of patients with medulloblastoma who developed extraneural metastases.

We retrospectively reviewed a departmental database over a 20 year period for all patients with medulloblastoma who developed extraneural metastases. Chart and imaging reviews were performed, and overall survival (OS) estimated by the Kaplan-Meier method.

We found 14 patients with medulloblastoma and extraneural metastases. The median age at initial diagnosis was 16.3 years (range, 3.2-44.2), and the most common subtype was desmoplastic (n = 6, 42.9%). After initial gross total resection, most patients received radiation therapy alone (n = 10, 71.4%). Metastases to bone were most common (n = 11, 78.6%) followed by metastases to bone marrow (n = 6, 42.9%), usually to the spine. The median time from initial diagnosis to first extraneural metastasis was 1.5 years (range, 0.2-17.4), and the median OS from extraneural metastasis to death was 3.3 years (range, 0-18). The Kaplan-Meier estimate of 5 year OS from extraneural metastasis diagnosis was 40.0% (95% CI, 20.2-79.2).

Extraneural metastases from medulloblastoma may rarely develop after initial diagnosis to involve bone and bone marrow. We found that desmoplastic variant extraneural tumors had longer survival than nondesmoplastic variants, suggesting that histopathological and more recent molecular subtyping have important roles in determining the prognosis of medulloblastoma patients.