A report describes a case of a woman in her 60s, skin phototype III, who presented with a pigmented lesion on her left foot that had been growing slowly for the last five years. 

Clinical examination revealed a well-demarcated, non-desquamative, irregularly pigmented dark patch with a diameter of 6 cm over the internal border of the first left metatarsophalangeal joint.

Dermoscopy revealed superficial fine, wispy pigmented spicules that did not follow the dermatoglyphic lines, resembling pigmented hyphae in the stratum corneum. A direct mycological examination showed irregular, branching, septate dematiaceous hyphae and yeast-like cells with spores. Furthermore, a superficial shave biopsy revealed multiple hyphae on the corneal layer, confirming the diagnosis of tinea nigra. She received treatment with topical cetoconazol, which resulted in complete resolution.

Palmeiro AG, Sampaio R, Miroux-Catarino A. Slow-growing pigmented acral lesion. BMJ Case Reports CP. 2022;15:e253453.