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Título

Desmoplastic Medulloblastoma in an Adult Patient: Case Report

RESUMO

Case Presentation: A 28-year-old female patient underwent a biopsy of a spinal cord (SP) and cerebellar tumor. Grossly, the fragments from both sites were brownish, firm and irregular. The histopathological examination of the two tumors showed an undifferentiated neoplasm with cells with hyperchromatic nuclei and high biphasic cellularity, ranging from compact to loose. An immunohistochemical panel was performed with synaptophysin, chromogranin, enolase, CD45, TTF1, PAX5, CD99, GFAP and KI67 cell proliferation index (KI67-CPI). The results showed positivity for enolase and focal positivity for synaptophysin and chromogranin. The KI67-CPI was 70%, being lower in nodules. Discussion: Medulloblastoma (MB) is a primitive neuroectodermal tumor. Although MB is the most common brain neoplasm in children, it is very rare in adults, with an estimated incidence of 0,6 cases per million per year. Normally, it emerges in posterior fossa structures, specially the cerebellum, and tends to disseminate through the cerebrospinal fluid pathways, being especially prone to leptomeningeal spread. Rarely, other malignant tumors with small cell morphology can be found, including small cell glioblastoma, which can typically be excluded by immunohistochemistry, using lineage markers or entity specific stains. The desmoplastic variant is a subtype of MB with medium to high risk. Our case presents the rare manifestation of a desmoplastic MB in cerebellum and SP in the same patient. Intramedullary spinal dissemination is rare, with very few cases in the available literature. We find no previous scientific report of a desmoplastic MB in SP, but there are seven documented cases of small cells MB in SP, with two of them appearing simultaneously to an extramedullary component, as in our report. Final Comments: In adulthood, MB has a higher proportion of desmoplastic histological features, different proliferation rates and a tendency for late relapses. The therapeutic role of adjuvant chemotherapy in adults is still not entirely known due to a shortage of prospective studies. Surgical resection plays a central role in treatment and should be regarded individually, according to the status of the patient's disease. Thus, further studies on the occurrence of MB in adults and on SP involvement are needed, in order to better understand prognostic factors and the best treatment options.

Palavras Chave

Desmoplastic Medulloblastoma; Spinal Cord neoplasm; Cerebelar neoplasm; Neuropathology