Photo Rounds

Dark rash under breasts

A 52-year-old woman sought care for a dark, somewhat itchy rash under her breasts that she’d had for a year. She was overweight and had diabetes and hypertension, which were not well controlled. She had tried talcum powder to keep the area dry, but the rash persisted. Her skin was otherwise normal.

What’s your diagnosis?


The family physician (FP) suspected that the patient had some type of fungal infection under her breasts. The FP scraped the edge and performed a potassium hydroxide (KOH) preparation that showed pseudohyphae and budding yeast forms, indicating a candida infection. (See video on how to perform a KOH preparation.) The FP also noted that there appeared to be some satellite lesions around the edge of the hyperpigmented area. Under the left breast was a small fissure and some white coloration at the skinfold. The differential diagnosis included tinea corporis and inverse psoriasis.

The FP prescribed topical clotrimazole cream 1% over the counter to be applied twice daily until at least one week after the rash resolved. While nystatin would be another option, it required a prescription and would not cover any possible dermatophyte in the area. The FP also explained that the dark pigmentation is the result of a longstanding inflammatory process related to the infection and would not go away immediately with treatment. In fact, the postinflammatory hyperpigmentation might remain for life.

The FP also spent time counseling the patient on an improved diet, increased exercise, and adherence to her diabetes medicines. A follow-up appointment for one month was set to review the patient's general health and to see if the candida infection resolved.

In cases where intertriginous fungal infections are treated without KOH or fungal culture confirmation, be suspicious for inverse psoriasis if the patient does not respond to antifungal medications. With such a large area involved, an oral antifungal such as fluconazole might occasionally be needed. Terbinafine is not an effective medicine for cutaneous candidiasis. If psoriasis is suspected, it helps to look for clues, such as nail pitting or cutaneous involvement with plaques on the elbows, knees, or scalp. If all else fails, a punch biopsy can be used to determine the correct diagnosis.

Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Usatine R. Candidiasis. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill; 2013:777-781.

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