Tinea nigra: a rare imported infection

A Special Tinea Nigra Caused by Curvularia lunata: Case Report and Literature Review

Tinea nigra is a superficial fungal infection usually caused by Hortaea werneckii (H. werneckii). We report a special case of tinea nigra in an immunocompetent child who developed a unilateral, rapidly growing pigmented lesion on her palm. Interestingly, Curvularia lunata (C. lunata) was isolated from the lesion scrapes and was identified by both morphological features and molecular biology methods. The lesion was completely cleared by topical naftifine hydrochloride and ketoconazole cream. We present-to the best of our knowledge-the first case of tinea nigra where the causative pathogen was identified as C. lunata. We therefore provide a brief literature review of previously reported cases of tinea nigra to broaden the knowledge of the potential causative pathogens. The etiology, demography, clinical features, diagnostic methods, and treatment of the reviewed cases are summarized and analyzed.

[First autochthonous case report of tinea nigra in Chile]

Tinea nigra is an infrequent superficial mycosis caused by the dematiaceous fungus Hortaea werneckii. It usually occurs in tropical coastal areas, with very few reports in South American countries with temperate climates, generally corresponding to infections imported by travelers. We present the case of a Chilean adult patient, with no previous history of recent trips, with clinical and microbiological background consistent with palmar tinea nigra, treated with oral itraconazole and topical sertaconazole with a favorable response. This article is the first case reported in Chile, of autochthonous origin.

In vitro activity of nine antifungal agents against a global collection of Hortaea werneckii isolates, the agent of tinea nigra

The in vitro susceptibility of molecularly identified Hortaea werneckii isolates (n = 37), the causative agent of tinea nigra, originating from clinical and environmental sources was determined for nine antifungal agents. Posaconazole had the lowest geometric mean minimum inhibitory concentration (GM MIC) (0.07 µg/mL), followed by voriconazole (0.13 µg/mL), isavuconazole (0.14 µg/mL), itraconazole (0.16 µg/mL), terbinafine (0.19 µg/mL) and amphotericin B (0.92 µg/mL). In contrast, fluconazole (14.56 µg/mL), caspofungin (2.41 µg/mL) and anidulafungin (1.42 µg/mL) demonstrated the highest GM MICs/MECs against H. werneckii.

Scanning electron microscopy of tinea nigra

Tinea nigra is a rare superficial mycosis caused by Hortaea werneckii. This infection presents as asymptomatic brown to black maculae mostly in palmo-plantar regions. We performed scanning electron microscopy of a superficial shaving of a tinea nigra lesion. The examination of the outer surface of the sample showed the epidermis with corneocytes and hyphae and elimination of fungal filaments. The inner surface of the sample showed important aggregation of hyphae among keratinocytes, which formed small fungal colonies. The ultrastructural findings correlated with those of dermoscopic examination - the small fungal aggregations may be the dark spicules seen on dermoscopy - and also allowed to document the mode of dissemination of tinea nigra, showing how hyphae are eliminated on the surface of the lesion.

Dermoscopy revealing a case of Tinea Nigra

Dermoscopy has being used over the past twenty years as a noninvasive aid in the diagnosis of innumerable skin conditions, including infectious diseases and infestations (Entodermoscopy).Tinea nigra is a superficial phaeohyfomycosis that affects mainly the glabrous skin of palms and soles. We describe a 14 year-old girl with a three-month history of an enlarging brown patch of her hand diagnosed as Tinea Nigra following clinical and dermoscopy examination.These images emphasize the importance of dermoscopy as a diagnostic tool in the daily routine of dermatologists.