title: Tinea nigra showing a parallel ridge pattern on dermoscopy.
abstract: An 18-year-old healthy female student noticed a brown macule measuring 21 mm in diameter on the left palm and visited our clinic concerned about a cancerous mole. Dermoscopic examination revealed a brown, fine-dotted and granule-like structure overlapping an amorphous light brown macule. However, unlike previous cases, analysis of the high dynamic range-converted image revealed the parallel ridge pattern frequently observed in malignant melanomas. Brown mycelia were detected on direct microscopic examination; black colonies were isolated on fungal culture and the fungus was identified as Hortaea werneckii. The lesion was treated with topical ketoconazole cream, and it diminished 1 month later.
authors.affiliation: Noguchi Dermatology Clinic, Kumamoto, Japan; Department of Immunology, Allergy & Vascular Biology, Kumamoto University, Kumamoto, Japan.
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Noguchi
authors.forename: Masataro
authors.initials: M
authors.lastname: Hiruma
authors.forename: Yuji
authors.initials: Y
authors.lastname: Inoue
authors.forename: Keishi
authors.initials: K
authors.lastname: Miyata
authors.forename: Masaru
authors.initials: M
authors.lastname: Tanaka
authors.forename: Hironobu
authors.initials: H
authors.lastname: Ihn
mesh_terms: D000293:Adolescent; D001203:Ascomycota / Q000302:isolation & purification; D005260:Female; D006229:Hand Dermatoses / Q000382:microbiology / Q000473:pathology*; D006801:Humans; D014005:Tinea / Q000382:microbiology / Q000473:pathology*
keywords: Hortaea werneckii; dermoscopy; palm; parallel ridge pattern; tinea nigra