ダーモスコピーが診断に有用であったTrichophyton rubrumによる爪甲色素線条

・右拇趾の爪甲色素線条を呈した爪白癬を報告した．

・臨床的に爪部の色素性母斑やBowen病，悪性黒色腫などと鑑別を要した．

・ダーモスコピー所見とKOH検査，真菌培養検査によりTrichophyton rubrum（T. rubrum）感染による爪白癬と診断した．

・テルビナフィンの内服療法のみで爪甲色素線条は消失した．

・爪白癬による爪甲色素線条の診断においてもダーモスコピー所見は有力な検査法と考えられる．

（「症例のポイント」より）

　

A case of melanonychia caused by Trichophyton rubrum in which dermoscopy was useful for diagnosis

　

Kurihara, Mana1）Kimura, Utako1）Tanaka, Masaru3）Hiruma, Masataro4）Takamori, Kenji2）Suga, Yasushi1）

1）Department of Dermatology, Juntendo University Urayasu Hospital

2）Juntendo University

3）Department of Dermatology, Tokyo Women’s Medeical Univercity Medical center East

4）Ochanomizu Institute for Medical Mycology and Allergology

　

A woman in her 60s visited our hospital with the chief complaint of pigmented lines on the nail of the right big toe. Malignant melanoma and pigmented nevus were excluded by dermoscopy. A KOH test was positive for fungal elements, and the causative agent was morphologically and molecular biologically identified as Trichophyton rubrum. We diagnosed the patient as having tinea unguium and melanonychia caused by T. rubrum, and the lesion was considered to be caused by the chromogenic fungus of T. rubrum. The patient was cured with oral terbinafine. A KOH test and fungal culture test are important for diagnosis. In addition, we believe that dermoscopy could be a promising test method.