髄膜炎で発症したSacrococcygeal dermal sinusの稀な1症例

Sacrococcygeal Dermal Sinus Presented Bacterial Meningitis : A Case Report

要旨　髄膜炎で発症したsacrococcygeal dermal sinusの稀な1例を経験し，その特徴および治療について文献的考察を加え報告した。症例は10カ月の男児。遷延する髄膜炎にて発症 した。皮膚洞は，仙尾部皮膚からいったん尾側に下降した後，終糸と一体となり脊髄に移行しており，その内部にdermoid cystを伴うという特異な形態を呈していた。Sacrococcygeal dermal sinusは，仙尾部以外の先天性皮膚洞と発生過程が異なり，その発生にcaudal cell massが関与しており，臨床症状，病理学的形態，特に，同様にcaudal cell massから形成される終糸との関連において他部位に発生する皮膚洞と差異が生じているものと推察される。鑑別すべきものとして，出生児の1～4％に認められるcoccygeal pitがあるが，今回得られた知見は，仙尾部に皮膚異常を認める乳幼児の鑑別診断に極めて重要であると考えられた。

A rare case of sacrococcygeal dermal sinus suffering from relapsing meningitis is presented. In addition, deference of clinical figure and pathology between sacrococcygeal region and other regions are discussed. A 10-month-old boy was suffering from relapsing meningitis. Spinal MRI was performed to find occult spinal dysraphism because he had a pit on his hip. The MRI revealed sacrococcygeal dermal sinus. He received surgical resection of dermal sinus based on this findings. Interestingly, different from other dermal sinuses, the dermal sinus runs to caudal direction, and was fused filum terminale with dermoid cyst. This interesting pathological feature of sacrococcygeal dermal sinus seems to come from developmental difference between sacrococcygeal dermal sinus and the other dermal sinuses. Only sacrococcygeal dermal sinus is related with caudal cell mass on its pathogenesis. Because filum terminale is also developed from caudal cell mass, sacrococcygeal dermal sinus seems to be related with filum terminale. Most important differential diagnosis is coccygeal pit that is found in 1～4％ of newborn baby. The clinical feature and pathology got from our case must be very helpful to distinguish sacrococcygeal dermal sinus from coccygeal pit.