Tinea nigra palmaris: differentiation from malignant melanoma or junctional nevi.

Tinea nigra usually presents as a brown to black macule on the palmar or plantar skin and is sometimes misdiagnosed as a malignant melanoma or as a junctional nevus, prompting unnecessary surgical procedures and anguish for the patient. Superficial scraping of the skin for microscopic inspection with potassium hydroxide reveals pigmented hyphae, easily confirming the diagnosis of tinea nigra.