乳児松果体部matignant rhabdoid tumorの1例

A case of malignant rhabdoid tumor in the pineal region in early infancy

I．はじめに

　乳児期発症の中枢神経系腫瘍は稀であり，かつ同時期に発生する悪性脳腫瘍は，年長児と比べ治療は難渋し，予後も不良である^2,4,7）．今回われわれは，乳児期松果体部に発生した脳腫瘍に手術，化学療法を施行し一過性の腫瘍縮小効果を得たが，その後間もなくして，急速な腫瘍再増大を来たした症例を経験した．その臨床経過，病理組織所見から中枢神経系発生のrhabdoid tumorと診断した．同疾患は乳幼児期に発生する極めて悪性経過をたどる腫瘍であり，近年欧米からの報告が相次いでいる^5,6,9-11）．しかし，本邦からの報告はわれわれが渉猟し得た中で1例のみであるため^13），同疾患について若干の文献的考察を加え報告する．

A 6-month-old girl was admitted to another hospital because of consciousness disturbance, preceded by 2 weeks of decreased activity and vomiting. She was re-ferred to our hospital after ventricular drainage had been instituted for hydrocephalus and the tumor in the pineal region. The patient was noted to have conju-gate upward gaze palsy and papilledema. CT scan and MRI revealed a large tumor in the pineal region with tumoral hemorrhage and a small mass in the right fron-tal lobe. At surgery, the pineal region tumor was re-moved subtotally. Histological examination showed the tumor to be composed of sheets of large polyhedral or round cells with an eccentric round nuclei, prominent nucleoli, and cytoplasmic inclusions. Immunohistoche-mical studies were positive for GFAP, vimentin, S-100, CK, EMA, and SMA, but negative for AFP, HCG, PLAP, and CEA.

Following surgery, she received three 5-day cycles of chemotherapy, consisting of intravenous administration of cisplatin 20 mg/m2/day and etoposide 60mg/m2/ day. After these therapies, MRI showed a decrease in the area of high intensity in the pineal region, but almost no change in the right frontal mass lesion. Fol-low-up radiological examination showed that the tumor had grown rapidly one month after chemotherapy and the patient died 5 months after her first hospitalization. Malignant rhabdoid tumor of the CNS is rare and re-markably malignant. This tumor should be treated us-ing multidisciplinary management with surgery, inten-sive chemotherapy, and radiotherapy depending on the patient's age.