Pitted keratolysis is a bacterial infection of the skin that affects the soles of the feet or the palms of the hands. It causes depressions or pits in the top layer of the skin.

People with physical jobs that require them to wear enclosed footwear for extended periods, such as those working as farmers or soldiers, may be more likely to develop the infection because bacteria thrive in dark, moist conditions.

In this article, learn more about pitted keratolysis, including its causes, symptoms, and treatment.

Pitted keratolysis on the feet. Image credit: Evan Saap, 2016Share on Pinterest
Pitted keratolysis can affect both the feet and hands.
Image credit: Evan Saap, 2016

Pitted keratolysis is a bacterial infection of the skin. It can affect the palms of the hands and, more commonly, the soles of the feet, particularly the weight-bearing areas.

This infection causes small depressions, or pits, in the top layer of the skin. It can also lead to a bad smell.

Pitted keratolysis usually affects people who wear enclosed warm footwear for long periods, including soldiers, sailors, and athletes. It also tends to be common in tropical areas where people usually go barefoot.

The bacteria species Kytococcus sedentarius, Dermatophilus congolensis, Corynebacterium, or Actinomyces usually cause the infection.

These bacteria thrive in moist environments. According to the American Osteopathic College of Dermatology, pitted keratolysis has an association with excessive sweating, but this is not its only cause.

Perspiration, along with tight fitting socks or shoes, creates the perfect conditions for the bacteria to multiply.

Other risk factors for pitted keratolysis include:

  • not drying the feet thoroughly after bathing
  • not wearing absorbent socks
  • sharing towels with others

People whose occupation may increase their risk of pitted keratolysis include:

  • athletes
  • farmers
  • sailors and fishing workers
  • industrial workers
  • people who work in the military

Other risk factors that can make someone more likely to develop pitted keratolysis include:

  • hot, humid weather
  • sweating a lot on the hands or feet
  • having thickened skin on the palms or soles
  • having diabetes
  • being older
  • having a compromised immune system

The main symptom of the infection is clusters of small pits in the top layer of the skin on the soles of the feet. Each pit is usually 1–3 millimeters in size. The skin may also look white or wrinkly.

The pits usually cluster around the balls of the feet, the heels, or both. They tend to appear more pronounced when the feet are wet. Without treatment, the pits can join together to form a large crater-like lesion.

Pitted keratolysis can also cause an unpleasant smell, but people do not usually experience any redness or swelling because this condition is not an inflammatory skin condition.

Less commonly, the infection can affect the hands. When this happens, the characteristic pits usually occur on the palms.

A doctor will usually prescribe a topical antibacterial medication to treat the infection. Popular choices include:

  • erythromycin
  • clindamycin
  • mupirocin
  • fusidic acid
  • benzoyl peroxide

Rarely, the doctor may also recommend oral antibiotics, such as erythromycin or clindamycin. Effective treatment will usually clear the lesions and the smell in 3–4 weeks.

The doctor may also treat excessive sweating if it is contributing to the disorder. Aluminum chloride 20% solution or the off-label use of botulinum toxin injections are options that can decrease sweating.

People need prescription medications to treat pitted keratolysis. However, they can take some preventive measures to help stop the infection from coming back. These include:

  • wearing boots for as short a time as possible
  • wearing absorbent cotton or wool socks
  • washing the feet with soap or antiseptic cleanser twice a day
  • applying antiperspirant to the feet
  • avoiding wearing the same shoes 2 days in a row
  • avoiding sharing footwear or towels with other people
  • keeping the feet as dry as possible

Anyone who thinks that they have pitted keratolysis should speak to a doctor. The prescription antibacterial medicines necessary to treat the infection are only available from a healthcare professional.

The doctor will be able to make a quick diagnosis by looking at the affected area and asking the person a series of questions.

People who experience foot odor often try to treat the problem with over-the-counter products. Doing this can make the infection worse because these treatments tend to contain antifungal and antiperspirant ingredients that moisten, rather than dry, the foot.

Pitted keratolysis can affect anyone, but people who wear warm, closed footwear for long periods are particularly at risk.

Prescription antibacterial and antiseptic medicines can treat the infection. With the right treatment, the infection and the smell will usually clear up within a few weeks.

It is important to note that the infection can come back. People can help prevent this by ensuring that they keep their feet dry and by avoiding wearing enclosed footwear whenever possible.