小児におけるシルビウス裂内dermoid cyst—症例報告と文献的考察

Intrasylvian Dermoid Cysts of the Pediatric Patient: A Case Report and Review

Ⅰ．はじめに

　テント上dermoid cystは，小児において遭遇する頻度が比較的低い占拠性病変の1つである^6,12)．しばしばdermal sinusに合併して後頭蓋窩や正中部に同定されることが一般的で，悪性組織ではないものの内容物の分泌に伴って緩徐に増大し症状を来す^2,5)．一方，さまざまな放射線学的特徴を有しており，術前検査のみで本疾患を疑うことは容易とは言えない^6,8)．Schneiderらによる過去の報告例の検討では，小児におけるテント上dermoid cystは多くの場合，前頭蓋底や鶏冠といった正中部に局在していることが多く，外側部におけるケースは1例のみしか報告されていない¹²⁾．今回われわれは，右シルビウス裂内に占拠性病変を認め，摘出後にdermoid cystの診断が得られた小児例を経験したので報告する．過去の症例と同様に，本症例のMRI画像も特異的でなく，術前診断に難渋した．症例提示とともに，過去に報告された小児シルビウス裂内dermoid cystとの比較・考察を行う．

　Objective:Supratentorial dermoid cysts are unusual benign mass lesions in pediatric patients, especially if located in a lateralized position such as in the lateral sulcus. Since these lesions often adhere tightly to circumjacent nerves or vessels, preoperative evaluation is important. Here we report on a pediatric patient with an intrasylvian dermoid cyst who underwent radical microsurgical resection and review the relevant literature.

　Methods:An 8-year-old girl with a cystic space-occupying lesion in the right lateral sulcus was referred to our hospital. The lesion appeared similar to CSF on T1/T2 sequences on magnetic resonance imaging（MRI). However, diffusion-weighted imaging（DWI）indicated high diffusion restriction. During the operation, dermal appendage was found within the tumor capsule. Gross total resection was achieved and the patient was discharged without any deficits. Histological findings confirmed the diagnosis of a dermoid cyst.

　Discussion:Only three cases of pediatric patients with dermoid cysts located in the lateral sulcus have been described. Due to its rarity and highly variable appearance on MRI, obtaining a differential diagnosis is difficult. Gross total resection should be the surgical goal;nevertheless, adjacent structures must be preserved.

　Conclusion:Here we described an additional rare case of intrasylvian dermoid cyst in childhood. The appearance of such cysts on DWI can aid with their preoperative diagnosis.