Pitted keratolysis (also known as Keratolysis plantare sulcatum, Keratoma plantare sulcatum, and Ringed keratolysis) is a bacterial skin infection of the foot. The infection is characterized by craterlike pits on the sole of the feet and toes, particularly weight bearing areas. The infection is caused by Corynebacterium species bacteria and Kytococcus sedentarius. Excessive sweating of the feet and use of occlusive footwear provide an environment in which these bacteria thrive and therefore increase the risk of developing pitted keratolysis.The condition is fairly common, especially in the military where wet shoes/boots are worn for extended periods of time without removing/cleaning. Skin biopsy specimens are not usually utilized, as the diagnosis of pitted keratolysis is often made by visual examination and recognition of the characteristic odor. Woods lamp examination results are inconsistent. Treatment of pitted keratolysis requires the application of antibiotics to the skin such as benzoyl peroxide, clindamycin, erythromycin, fusidic acid, or mupirocin. Prevention efforts aim to keep the feet dry by using moisture-wicking shoes and socks as well as antiperspirants. Signs and symptoms
Pitted keratolysis typically presents with white discoloration of the skin and numerous discrete, "punched-out" pitted lesions or erosions, usually located on the soles of the feet. The pits are typically 1–7 millimeters in diameter. These circular and shallow pits are characteristic of pitted keratolysis, and often overlap to produce larger areas of erosion. The appearance of this condition’s characteristic lesions becomes more pronounced when the affected area is wet or submerged in water.
However, a potassium hydroxide preparation can help rule out the presence of a fungal infection. Imaging and biopsy are not necessary. Differential diagnosis
Acid
Athletes foot (Tinea pedis)
Erythrasma
Hyperhidrosis

Treatment
As of 2014, there is little high-quality evidence to provide guidance and support one treatment method over another. Therefore, the optimal treatment approach for pitted keratolysis remains unclear as the condition has not been well-studied. One review suggested a treatment approach requiring modification of risk factors (e.g., keeping feet clean and dry) and treating the underlying bacterial infection. Effective antibiotic options include clindamycin, erythromycin, mupirocin, and fusidic acid. Topical clindamycin is generally preferred as the first-line choice due to lower cost and better availability. Fusidic acid is preferred over mupirocin in most cases due to less resistance to fusidic acid amongst Methicillin-sensitive staphylococcus aureus and Methicillin-resistant staphylococcus aureus. Benzoyl peroxide is an effective alternative over-the-counter option and is thought to be as effective as topical clindamycin. Clinical cure was typically seen after 2.5–3 weeks. Oral antibiotics are not typically recommended.Foot hygiene is important. The feet may be washed at least daily with soap and water, and dried thoroughly afterwards. Moisture-wicking socks and shoes may be worn and antiperspirants, such as aluminum chlorohydrate, may help to keep the feet dry. Injections of botulinum toxin have successfully induced cessation of sweating (anhidrosis) of the soles of the feet and led to resolution of pitted keratolysis.