Klippel-Feil症候群を伴った第4脳室類皮腫の1例

Dermoid Cyst in the Fourth Ventricle Associated with Klippel-Feil Syndrome

　中枢神経系類皮腫には二分脊椎などの先天異常を合併することがよく知られている。今回，我々はKlippel-Feil症候群を合併した第4脳室の類皮腫を経験した。症例は47歳の男性で一過性四肢麻痺で発症した。頭部CT, MRIで脳梗塞と共に第4脳室に占拠性病変を認めた。入院時，左片麻痺，右側優位の運動失調を呈し，外見上，顔面非対称，短頸，毛髪線低位が存在し，頸椎X線で第2-3頸椎の癒合を認めた。腫瘍摘出時，毛髪が確認され，組織学的所見と併せ類皮腫と診断した。

　類皮腫の発生原因やその時期については様々な説が報告されているが，今回の症例は類皮腫にKlippel-Feil症候群と頬骨肥大が合併しているため，後2者の発生原因・時期から類皮腫も中胚葉の障害が神経管閉鎖不全をきたした結果生じ，その時期も胎生第3〜4週である可能性が高い。

Dermoid cysts in the central nervous system are often associated with various congenital disorders, especially dermal sinus and spina bifida.

We report a case of dermoid cyst in the fourth ventricle associated with Klippel-Feil syndrome. A 47-year-old man with a long history of headache had been known to have a cystic lesion in the posterior fossa for 12 years. When he was reffered to our hospital with complaints of transient tetraparesis, he showed bilateral cerebellar ataxia and minimal left hemiparesis. Furthermore, he was noted to have a webbed neck with a low hairline and facial asymmetry. CT and MRI showed multiple cerebral infarctions as well as a mass lesion in the posterior fossa. Cervical roentgenogram showed a fusion of C 2 and C 3 vertebrae. The tumor was totally removed via a suboccipital approach, and the diagnosis was a dermoid cyst.

The present patient had not only dermoid cyst and Klippel-Feil syndrome but also hypertrophy of the zygomatic bone. The pathogenesis of the Klippel -Feil syndrome is presumed to be an intrauterine defect, with a failure of segmentation of mesoder-mal somites. The zygomatic bone is also derived from the mesoderm somites at early fourth week, too. From these points of view, the disturbance in the mesoderm before the fourth week of gestation might have played an important role in causing a dermoid cyst.