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Dermoscopy case of the month
Tinea nigra: A diagnostic pitfall

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Clinical presentation

A 13-year-old girl presented with a pigmented lesion on her left palm with a quadrangular shape measuring 2 × 2 cm (Fig 1). The lesion, which appeared 2 years before, after a trip to a Greek island, was interpreted as melanocytic by other dermatologists.

Dermoscopic appearance

Dermoscopy showed a patch with a weak pigmentation composed of thin bundles of spicules that were arranged in a parallel ridge pattern (Fig 2).

Microbiological diagnosis

The microscopic examination with potassium hydroxide showed ramified and brownish spores and hyphae and 3 weeks later the culture with Sabouraud dextrose agar revealed dark-colored colonies composed of oval and fusiform cells identified as Hortaea werneckii (Fig 3). We therefore made the diagnosis of tinea nigra. The patient was treated with isoconazole 1% cream 2 times daily for 3 weeks, achieving a complete remission.

Key message

Tinea nigra is a superficial and asymptomatic fungal infection

References (2)

  • P.R. Criado et al.

    Dermoscopy revealing a case of tinea nigra

    An Bras Dermatol

    (2013)
  • H. Noguchi et al.

    Tinea nigra showing a parallel ridge pattern on dermoscopy

    J Dermatol

    (2015)

Cited by (0)

Funding sources: None.

Conflicts of interest: None declared.

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