The FP diagnosed pitted keratolysis in addition to hyperhidrosis. Pitted keratolysis is a superficial foot infection caused by Gram-positive bacteria, including Kytococcus sedentarius, Corynebacterium species, and Dermatophilus congolensis.
These bacteria produce proteases that degrade the keratin of the stratum corneum, leaving visible pits on the soles of the feet. The associated malodor is likely secondary to the production of sulfur byproducts.
Pitted keratolysis is more common in men and is often a complication of hyperhidrosis. It’s associated with an itching and burning sensation in some patients. The condition usually involves the callused pressure-bearing areas of the foot, such as the heel, ball of the foot, or plantar great toe.
Treatment is based on eliminating bacteria and reducing the moist environment in which the bacteria thrive. Topical erythromycin or clindamycin solution can be applied twice daily until the condition resolves. It may take 3 to 4 weeks to clear the odor and skin lesions. Oral erythromycin is effective and may be considered if topical therapy fails. Treating underlying hyperhidrosis is also important to prevent recurrence.
The FP prescribed topical erythromycin solution for the pitted keratolysis and topical 20% aluminum chloride for the hyperhidrosis. The physician also suggested that the patient wear a lighter and more breathable shoe until his condition improved.
Photo and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Babcock M, Usatine R. Pitted keratolysis. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill; 2013:686-688.
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