Pitted Keratolysis: What Is It & How to Treat It?

Pitted keratolysis is a bacterial skin infection that affects the soles of your feet. Its characteristic skin pitting, odor, pain, and itching can make it debilitating, but with prompt diagnosis and the correct combination of treatments, it can be treated successfully. Our team at Gurnee Podiatry & Sports Medicine Associates will explain what pitted keratolysis is, including its causes, symptoms, and treatment.

What Is Pitted Keratolysis?

Pitted keratolysis is a bacterial infection that affects the stratum corneum, the outermost layer of the skin of the soles of the feet. This skin disorder leads to skin thickening and the development of small crater-like lesions that predominantly affect weight-bearing areas of the sole of the foot. It’s also called:

• Ringed keratolysis.
• Keratolysis plantare sulcatum.
• Keratoma plantare sulcatum.

Causes of Pitted Keratolysis

Pitted keratolysis is primarily caused by gram-positive aerobic bacteria of the Corynebacterium family. These bacteria colonize the stratum corneum, using proteolytic enzymes to create small tunnels and pitting. Other bacteria that can cause this condition include the following:

• Micrococcus sedentarius.
• Dermatophilus congolensis.
• Kytococcus sedentarius.

The bacteria that cause pitted keratolysis thrive in the warm, sweaty environment created by wearing occlusive or wet footwear for prolonged periods. This affects the incidence of pitted keratolysis with marked variation in its rate of occurrence by environment and occupation. This condition isn’t contagious but is more prevalent in males than females. It’s also associated with sports, such as running , and occupations that include the following:

• Farmers.
• Construction workers.
• Military personnel.
• Heavy industry workers. 

Research has identified other causative factors, including obesity, poor foot hygiene and care, diabetes, and immunosuppression. 

Symptoms of Pitted Keratolysis 

Pitted keratolysis is often first noticed because of the discomfort it causes. Common symptoms of this podiatric condition include the following:

• Presence of excessive sweating: The sweating caused by pitted keratolysis isn’t related to the temperature or the feet’s activity. 
• Malodor: The bad smell that comes from infected feet is caused by the bacteria’s activity and secondary fungal infections.
• Pitting: The bacterial colonization produces characteristic indentations that can coalesce to cause cratering of the thickened skin of the soles. These tender pits usually have a diameter of between 1 and 7 millimeters.
• Skin maceration on the soles: The excessive sweating softens and breaks down the outer layer of the skin on the feet. This leads to wrinkling, peeling, and flaking of affected parts of the sole.
• Foot discomfort: Pain, itching, and a burning sensation are often experienced when walking. The pain may be reduced in patients with diabetic neuropathy.

Diagnosing Pitted Keratolysis

Pitted keratolysis may easily be mistaken for other common podiatric conditions, including hyperhidrosis, athlete’s foot, or erythrasma. Dr. Bever and Dr. Schoene can diagnose pitted keratolysis with a thorough visual examination of your feet. Other methods used for a definitive diagnosis of ringed keratolysis include the following:

Examination With a Dermatoscope

A dermatoscope is a visual tool that can help a podiatrist examine the skin of your feet in more detail. This hand-held tool uses light and magnification to delineate changes in the outer layers of your soles. The pits, lesions, and even bacterial colonies of pitted keratolysis may be seen.

Skin Biopsies for Bacterial Culturing

A diagnosis of ringed keratolysis can be confirmed with skin biopsies. Dr. Bever and Dr. Schoene can take a superficial skin shaving that can be cultured to identify the specific bacterial strain that has caused the skin infection. Causative bacteria can be identified using microscopy and staining. 

Wood’s Lamp Examination

The Wood’s lamp is another tool that’s available to a podiatrist to diagnose this skin infection. The lamp uses ultraviolet light to detect the characteristic fluorescence of certain bacteria and fungi. In pitted keratolysis, the skin may fluoresce red due to the presence of Corynebacterium.

Potassium Hydroxide

Infected skin scrapings can also be treated with potassium hydroxide (KOH) to exclude the presence of a fungal infection.  Filamentous fungal organisms show up on examination of KOH-treated skin scrapings, but it doesn’t directly diagnose ringed keratolysis.

How To Treat Pitted Keratolysis

Pitted keratolysis requires antibiotic treatment that eradicates bacterial infection. It’s unlikely to respond to home remedies, such as tea tree oil, apple cider vinegar, or over-the-counter treatments. Dr. Bever and Dr. Schoene  can prescribe the following treatments:

Topical Antibiotics

Topical antibiotic preparations are the primary method for treating pitted keratolysis. An effective regimen includes the twice-daily application of the antibiotic to the soles of the feet for two to three weeks. Suitable antibiotics include mupirocin, clindamycin, erythromycin, and fusidic acid. Antiseptics, such as benzoyl peroxide gel, may also be used.

Antiperspirants

Keeping the feet dry is important to treating this condition and preventing its recurrence. Your podiatrist can prescribe or direct you to use antiperspirants, such as aluminum chlorohydrate or medicated talcum powder. In severe cases of sweaty foot syndrome, botulinum toxin injections (Botox) may be used to cause anhidrosis, which can help to resolve the infection.

Moisture-Wicking Footwear

The holistic management of this foot condition includes changes to the socks and footwear you use. Dr. Bever and Dr. Schoene will advise you on breathable, moisture-wicking sock and footwear choices that can reduce the humidity and sweating of your feet. Medicated talc and drying agents, such as Drysol, can also be applied to the inside of shoes and socks to bring down moisture levels. 

Prevention of Pitted Keratolysis

Once pitted keratolysis has been treated, lifestyle changes and enhanced foot hygiene can help keep this condition away. Here are some behaviors that your podiatrist may encourage you to adopt to prevent the recurrence of pitted keratolysis: 

• Avoid wearing tight shoes or socks, especially rubber footwear.
• Expose the shoes to the open air after wearing them, especially if they’ve become wet.
• Avoid sharing towels or footwear with other people.
• Dry your feet thoroughly after bathing and apply talc.
• Wear socks made from cotton or other absorbent materials.
• Change your shoes and socks when they get wet.
• Wash your hands with soap and water after handling your shoes and socks.
• Wash your feet daily. 

Pitted keratolysis is an irritating foot condition, but it’s highly treatable and can be prevented by appropriate foot care. If you’re concerned that you may have this condition, consult Gurnee Podiatry & Sports Medicine Associates. Dr. Schoene, Dr. Bever, and our team of associate staff can promptly diagnose and treat this condition to return you to optimal foot health.