Microscopic local leptomeningeal invasion at diagnosis of medulloblastoma.

Abstract

To document the incidence and outcome of patients with microscopic local leptomeningeal invasion at presentation, children with medulloblastoma were reviewed. Nineteen patients (1-12 years of age), who had surgical resection (14 total, 5 subtotal) and were diagnosed as medulloblastoma, were evaluated for disease extent by pre- and postoperative computerized tomography/magnetic resonance imaging, histopathologic evaluation of leptomeninges adjacent to the resected tumor tissue, myelography/magnetic resonance of the entire spine, and analysis of cerebrospinal fluid cytology. Patients were also reviewed for disease outcome. Staging revealed one T2, nine T3a, eight T3b, and one T4 disease. There were 10 M0, 2 M1, 2 M2, 2 M3, and 3 Mx patients according to Chang's classification. Ten out of 19 patients (52.6%) demonstrated microscopic local leptomeningeal invasion. When only the 10 patients with M0 disease were considered, three out of five patients with microscopic local leptomeningeal invasion was found to have one or more relapses. The five other M0 patients without microscopic local invasion were in complete remission at the time of analysis. The incidence of microscopic local leptomeningeal invasion in patients with medulloblastoma is high. Whereas the impact on survival remains to be determined in larger series, data suggests prognostic role for isolated microscopic local leptomeningeal invasion, thus validity for inclusion in the future staging system.