Occasionally these lesions present with a green or brown hue around and within the pits.These superficial erosions are found under the toes and on the soles of the feet, and especially at the pressure bearing points such as the heel. Typically, both feet are equally affected. Rarely, the condition affects the palms. Cause
The most common cause of pitted keratolysis is Corynebacterium species. However, several other bacteria may also cause the condition, particularly Actinomyces keratolytica, Dermatophilus congolensis, Kytococcus sedentarius, and Streptomyces. Less frequently, it is due to Acinetobacter, Clostridium, Klebsiella, and Pseudomonas species. Pathogenesis
Pitted keratolysis is associated with excessive sweating of the palms or soles (palmoplantar hyperhidrosis.) The pits seen in pitted keratolysis are caused by bacteria secreting proteinase enzymes which cause the breakdown of the keratin proteins in the stratum corneum layer of the affected skin. This results in the formation of sulfur compounds which leads to a very strong and foul foot odor. The bacteria that cause pitted keratolysis thrive in warm and humid environments. Irritation is generally minimal, though occasionally burning, itching, and soreness are experienced with pitted keratolysis. Diagnosis
The diagnosis of pitted keratolysis is based primarily on the physical examination, with recognition of the classic pitted lesions and pungent odor. Dermoscopic examination can facilitate visualization of pits and pit walls. A Woods lamp may show coral red fluorescence, as seen in erythrasma. However, this finding is not uniformly present, as the condition may be caused by bacteria that do not produce fluorescent pigments. Further laboratory testing is not typically required for the diagnosis.
PMID 16710033. S2CID 25490586.