Erythematous plaques on the skin folds

A woman in her 50s presented with bilateral pruritic erythematous plaques in the submammary, axillary, genitofemoral, and intergluteal areas, that had been present for six months. The lesions had started in the submammary area then gradually progressed to the other areas. Intertrigo and dermatophytosis were initially suspected, but topical antifungal treatment was unsuccessful.

On examination, the lesions appeared as well demarcated, thin, bright red plaques, with a few discrete scales (fig 1, fig 2).

The patient had no lesions elsewhere on her body or nails. Her medical and drug histories were unremarkable and she had no family history of skin conditions.

Routine laboratory test results were normal or negative as were results for fungal microscopy and wood lamp examination for Corynebacterium minutissimum, the bacterium that causes erythrasma.

Histopathology of a left axillary skin …