Tinea Nigra Palmaris

Identical circular, chocolate-colored spots developed on a 4-year-old boy's palms 2 weeks ago, according to the child's mother. The sharply demarcated, macular lesions were asymptomatic.

This is tinea nigra, a superficial fungal infection caused by a black yeast, Exophiala werneckii, found in the southern coastal areas of the United States. It most commonly affects the palm or the volar aspect of the fingers and, less frequently, the feet. To differentiate tinea nigra lesions from melanoma or silver nitrate stain, examine a potassium hydroxide preparation of a scraping under the microscope.

Topical application of keratolytic and antifungal agents are effective therapy, writes Robert P. Blereau, MD of Morgan City, La. In this case, both lesions were treated with oxiconazole cream twice daily, and they cleared completely within 1 week.