This patient was suffering from pitted keratolysis and interdigital tinea pedis. Pitted keratolysis is caused by the bacterium Kytococcus sedentarius. Like tinea pedis, moist and sweaty feet provide a great environment for growth of this organism. The patient admitted to having sweaty feet—especially while playing soccer for hours. He also didn’t use shower shoes in the gym shower.
In pitted keratolysis, the bacteria live on the dead cells of the stratum corneum of the sole and form visible pits. In interdigital tinea pedis, the skin between the toes is white in appearance.
The FP recommended that the patient wear shower shoes and change his socks during the day if they become sweaty. He also prescribed topical 2% erythromycin solution to apply twice daily to the area with visible pits. In addition, the FP recommended that the patient buy over-the-counter topical terbinafine cream and apply it between the toes once or twice daily—especially after drying his feet well after a shower. A month later, both infections were clear.
Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Usatine R, Reppa R. Tinea pedis. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill; 2013:799-804.
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