小脳出血で発症した小児髄芽腫の1例

Pediatric Medulloblastoma Presenting as Cerebellar Hemorrhage: A Case Report

Ⅰ．はじめに

　髄芽腫（medulloblastoma）は小脳虫部を中心に発生し，第四脳室および両側小脳半球に浸潤性に進展していく悪性腫瘍である．ほとんどが15歳未満の小児に発生し，小児脳腫瘍の約20%を占めている⁵⁾．発症は腫瘍の増大に伴う急性水頭症や小脳失調に伴うものが多くを占め，出血による発症はわずかである．今回われわれは，小脳出血による発症を来し診断に苦慮した8歳女児の髄芽腫の症例を経験したので，文献的考察を加えて報告する．

　Medulloblastomas usually cause cerebellar ataxia and acute hydrocephalus owing to their increase in size. Cerebellar hemorrhage is an extremely rare initial clinical presentation of medulloblastoma. Herein, we report a case of medulloblastoma in an 8-year-old girl who presented with initial cerebellar intratumoral hemorrhage.

　The patient initially presented with mild headache;the differential diagnosis by using the initial computed tomography and magnetic resonance images was difficult, as bleeding from a cerebellar vascular malformation（cavernous angioma or arteriovenous malformation）was considered more likely. Hydrocephalus or typical findings indicative of medulloblastoma were not observed. We initially only observed the patient at another institution because the hematoma was relatively small（1.5×1×1cm). After follow-up imaging for pathological diagnosis, surgical removal was performed at our institute 49 days after the hemorrhage was observed. Complete tumor removal was achieved, and the histopathological diagnosis was medulloblastoma.

　The patient received whole brain and spinal irradiation（23.4Gy;posterior fossa local:50.4Gy）and chemotherapy（cyclophosphamide, 1,000mg/m²/day on day 1;vincristine, 1.5mg/m²/day on day 1;etoposide, 100mg/m²/day on days 1-3;cisplatin, 90mg/m²/day on day 2). No recurrences or neurological deficits were observed during a 2-year follow-up.

　This was a rare case of medulloblastoma presenting as cerebellar hemorrhage.

　Cerebellar medulloblastoma is among the common pediatric brain tumors;therefore, it should be diagnosed accurately and quickly.