Localized isotopic fungal infections, although rare, can occur in immunocompetent patients.

Necrolytic acral erythema is a newly described entity characterized by sharply demarcated scaly plaques on the dorsum of the hands and feet. More than 30 patients have been reported since 1996, all of whom had anti-hepatitis C virus antibody. A 32-year-old Taiwanese woman had been diagnosed with and treated for systemic lupus erythematosus with lupus nephritis about 10 years earlier. Soon thereafter, she noted several well-demarcated keratotic plaques with erythematous borders on her feet, with sparing of the soles. Histopathology showed diffuse parakeratosis with a neutrophil infiltrate, hypogranulosis, pale upper keratinocytes, scattered and grouped dyskeratotic cells, psoriasiform hyperplasia and a mild lymphocytic infiltrate in the upper dermis. The diagnosis was made after three biopsies. The lesions regularly worsened just before and during menstruation, but patch and intradermal tests for progesterone and estrogen were negative. There was no evidence of either hepatitis B or hepatitis C infection. The lesions did not respond to treatment with zinc. The rash regressed spontaneously when corticosteroids were stopped and recurred when they were restarted, finally resolving completely after she was treated with high-dose pulse steroids for her lupus.

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Aureobasidium pullulans is a ubiquitous black yeast-like fungus belonging to order Dothideales. It was regarded as a contaminant, but is now considered a pathogen causing a wide range of human infections. We report a case of superficial phaeohyphomycosis in an immunocompetent patient with clinical presentations mimicking tinea nigra. On microscopic examination of lesion scales, multiple thick-walled, pigmented oval spores with septa were noted. A fungus with black mucoid colonies was repeatedly isolated from the lesions during the treatment course. This fungus was identified as A. melanogenum on the basis of morphological characteristics and subsequently confirmed by sequencing internal transcribed spacers of ribosomal DNA. The clinical presentations and microscopic findings of lesion scales were considerably similar to those of tinea nigra. However, fungal culturing proved that the causative pathogen was A. melanogenum rather than Hortaea werneckii. The patient might have acquired this infection during gardening activities. We also reviewed reported cases of cutaneous A. pullulans infection.

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