Introduction:
Pitted keratolysis is a skin condition that affects the pressure-bearing area of the sole of the feet. It is characterized by pits or craters and malodor. It is also known as keratolysis plantare sulcatum and ringed keratolysis. It is a bacterial infection that occurs in an individual who wears tight shoes without proper ventilation. It can cause itchiness and a foul odor. It can be treated with antibiotics and has a good prognosis.
What Are the Causes of Pitted Keratolysis?
Ringed keratolysis is primarily a bacterial infection that can be caused by a range of bacteria such as Corynebacterium, Kytococcus sedentarius, Actinomyces, Dermatophilus congolensis, or Streptomyces. A moist environment is a breeding ground for bacteria; they thrive and multiply and produce enzymes that break down the upper layer of skin to leave pits or craters. The skin has different layers, the uppermost layer is called the stratum corneum, and it has a layer of keratin as an additional protective barrier. This keratin is thicker in palms and soles. The protease enzyme produced by the bacteria is strong enough to destroy this keratin layer. It primarily affects the soles of feet, and palms are spared. The sulfur compounds produced by the bacteria are responsible for the foul odor.
Who Are Affected?
Pitted keratolysis can affect all age groups, but it is most commonly seen in men than in women. The occupations that have a higher incidence of the disease may be the same reason for male predilection, such as:
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Industrial workers.
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Farmers.
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Athletes.
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Miners.
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Workers in a wet paddy field.
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Military men.
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Sailors and fishermen.
There are other factors that increase the risk of developing the condition, such as:
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Keratoderma (raised thickened skin of soles and palms).
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Hyperhidrosis (excessive sweating of palms and soles).
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Poor foot hygiene.
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Immunodeficiency.
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Prolonged use of covered footwear without airflow, such as rubber boots.
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Humid weather conditions.
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Maceration is when the skin becomes more wrinkled due to prolonged exposure to moisture. This can be found in paddy field workers and in individuals with excessive sweating, called hyperhidrosis. This condition aggravates bacterial infection or acts as a thriving factor for bacterial proliferation.
What Are the Clinical Features?
Pitted keratolysis is seen in pressure-bearing areas of the soles. It rarely affects palms as the area is less vulnerable to bacterial infection. However, it can be seen in paddy field workers. It is not usually painful but may be painful if associated with pruritus. It appears as pits on the keratin layer; they are irregular craters or erosions. It appears amplified when the feet are wet. It can appear brown, giving an unclean appearance. The feet may sweat excessively and appear slimy, which could be an aggravating factor for skin disease. Pitted keratolysis is associated with a foul odor. Some variations of pitted keratolysis have large crateriform depressions and are tender. They can present as plaques that are red and painful.
The variations of pitted keratolysis include:
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Corynebacterial triad, which includes erythrasma, trichomycosis axillaris, and pitted keratolysis.
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A painful plaque-like variant, which is red and tender.
Pitted keratolysis can affect all races and all skin types. As the condition is mainly asymptomatic, it does not cause many complications other than the psychological factor due to the foul odor and, in some cases, can cause mobility problems in painful conditions. There is a loss of the keratin layer of the stratum corneum. It heals on treatment and has a good prognosis.
Corynebacterium and Pitted Keratolysis:
Concurrent infections are often found along with pitted keratolysis, such as trichomycosis axillaris and erythrasma. It indicates that Corynebacterium is the causative factor for the three conditions.
How to Diagnose Pitted Keratolysis?
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Clinical features and distinctive foul odor are examined for diagnosis. Axilla and groin are examined for bacterial infections which are co-existing.
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A skin biopsy is done when there is uncertainty. Microorganisms are detected on stains.
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Skin scraping is done to rule out fungal infection.
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Wood lamp examination is done in the case of erythrasma; it shows coral red fluorescence. Erythrasma is a skin condition caused by Corynebacterium.
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Bacterial culture is done to identify the causative organism.
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Microscopic examination shows hyperkeratosis on the plantar surface of the soles of the feet.
How Is Pitted Keratolysis Treated?
Maintaining proper foot hygiene can prevent the condition. If it occurs, proper antibiotics, antiseptics, and maintaining foot hygiene can treat the condition.
General Management:
It mainly involves making sure foot hygiene is maintained, which includes:
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Avoiding occlusive footwear.
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Avoid tight footwear to reduce friction.
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Wear moisture-absorbent socks, and clean and change socks regularly.
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Follow cleanliness; wash legs with soap and water.
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Apply antiperspirant regularly.
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Avoid sharing footwear.
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If the patient has hyperhidrosis, it has to be maintained.
Specific Management:
Topical antibiotics are to be applied twice daily for two to four weeks. Medications included Clindamycin, Erythromycin, Mupirocin, and Fusidic acid. Oral antibiotics are administered in certain cases, such as Clindamycin or Erythromycin. It is given for ten days, but the duration depends on severity. Benzoyl peroxide is used for its antimicrobial and keratolytic properties. Pitted keratolysis can have periodic exacerbation and remission without treatment, and it heals within two to four weeks with treatment.
Conclusion:
Pitted keratolysis is a skin condition where the soles of the feet have pits or craters along with a characteristic foul odor. Different bacteria have been believed to be responsible for the disease, Corynebacterium being the most prominent. It is most commonly found in people who are exposed to moist environments for a prolonged period, athletes, or individuals who wear footwear that causes friction. It is a disease with a good prognosis and can be treated with topical antibiotics and proper hygiene maintenance.
