Study of the dermatoscopic pattern of tinea nigra: report of 6 cases

Digital dermatoscopy, a noninvasive auxiliary method that can improve the diagnosis of nearly all pigment skin lesions, was used to study 6 cases of tinea nigra, a rare dematiaceous superficial fungal infection and a potential mimicker of melanocytic nevus. Patients were first evaluated by a manual dermatoscope using a 10-fold magnification. The same patients were then reevaluated using a digital dermatoscope with 20-, 50-, and 70-fold magnifications. Direct mycologic examination and culture supported the establishment of the etiologic diagnosis. All reported cases showed a single dermatoscopic pattern. Manual and digital dermatoscopic images revealed irregularly distributed dark brown-pigmented dot lesions with filamentous aspect. The authors could not observe any melanocytic lesions. Cutaneous pigmented lesions, including superficial spreading melanoma, are the differential diagnosis. The dermatoscopic images are useful to help distinguish tinea nigra from other melanocytic diseases.