爪下外骨腫（Exostosis subungualis）の2例

EXOSTOSIS SUBUNGUALIS

I．緒言

　末節骨先端部爪甲下に軟骨性外骨腫を生ずるものを爪下外骨腫（Exostosis subungualis）といい，1817年，Dupuytrenの報告以来，欧米には多数の報告^1）があり，特に珍稀な疾患ではないが本邦報告例は少い。

　最近我々は，34歳主婦の右拇指先端に，また11歳男児の左第1趾先端内側に生じた本症の2例を経験したので，ここに報告し，その臨床像及び病因につき若干の文献的考察を行いたい。

Two cases of exostosis subungualis--a 34 year-old housewife, on the tip of the right thumb and an 11-year-old boy, in the inner aspect of the tip of the left first toe--were reported.

This disease is a cartilaginous exostosis in the subungual region on the tip of the ungual phalanx. Most of the cases occur in the young and middle aged and in the inner aspect of the peripheral end of the ungual phalanx of the first toe. It is a solitary, unilateral and hemispheri-cally elevated tumor the size of a pea. Its roentgenogram of a mushroom-type shadow, the broad base of which is connected to the cortex of bone of the ungual phalanx, is characteristic. From its clinical findings and roentgenogram, it is easily diagnosed. Although many etiologies, e.g. trauma theory and hamartoma theory, etc. have been enumerated, none of them is ap-plicable in all of the cases.

The histologic specimen from the authors' case 2 suggested that the tumor might start from lamina fibroelastica or the tissues around it.