Pitted and ringed keratolysis (keratolysis plantare sulcatum)

Published on 16/03/2015 by admin

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Pitted and ringed keratolysis (keratolysis plantare sulcatum)

Eunice Tan and John Berth-Jones

Evidence Levels:  A Double-blind study  B Clinical trial ≥ 20 subjects  C Clinical trial < 20 subjects  D Series ≥ 5 subjects  E Anecdotal case reports

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Pitted keratolysis (PK) manifests as shallow punched-out circular erosions, primarily on weight-bearing, sweaty areas of the feet, and less commonly on the non-weight-bearing areas of the feet and the palms of the hands. This superficial infection of the stratum corneum is caused by Corynebacterium, Dermatophilus, Actinomyces or Kytococcus (formerly named Micrococcus). These organisms possess keratin-degrading enzymes and produce sulfur-compounds, resulting in a foul odor. Hyperhidrosis and maceration often occur concurrently.

Management strategy

Most patients experience little or mild irritation. Maceration, foul odor, and soreness are the main reasons for consultation. Hyperhidrosis, sweat retention, prolonged occlusion, immersion and increases in the skin pH appear to be important causes of PK. Industrial workers wearing rubber shoes or soldiers whose feet are continually occluded or wet are at high risk of developing this infection. Initial management strategies should therefore include instruction on foot hygiene and avoidance of occlusive footwear.

Treatment involves use of topical or systemic antimicrobial agents and/or reduction of the hyperhidrosis.

The topical antibiotic most commonly used by the authors is fusidic acid, which can be prescribed as 2% fusidic acid cream or ointment three to four times daily. Topical 1% clindamycin, benzoyl peroxide, 1% clindamycin with 5% benzoyl peroxide gel, 2% erythromycin, mupirocin ointment, and tetracycline and gentamicin sulfate cream have been reported to be effective. Although 1% clindamycin hydrochloride can be made up with 660 mg dissolved in 55 mL of 70% isopropyl alcohol and 5% propylene glycol, we suggest Dalacin T topical solution may be used instead. This can be applied two or three times daily. Erythromycin 2% cream or ointment has been reported to be effective if used twice daily. We suggest using 2% erythromycin gel, available as Eryacne, or 2% erythromycin solution, available as Stiemycin. Japanese dermatologists have had some success in treating PK with gentamicin sulfate cream, but this is unavailable in the UK. Mupirocin 2% ointment may be administered two to three times daily; 3% tetracycline hydrochloride ointment may be applied one to three times daily. PK has also responded to topical antifungals such as clotrimazole and miconazole; 1% clotrimazole cream or 2% miconazole cream or ointment may be applied twice daily. Topical antiseptics can be effective.

Traditionally, systemic antibiotics have been reserved for severe and resistant cases, but a 7-day course of oral erythromycin at 250 mg four times a day is usually well tolerated. The use of penicillin or sulfonamides does not seem to be effective. Antibiotic resistance has been reported with Micrococcus sedentarius to penicillin, methicillin, ampicillin, oxacillin, and erythromycin.

Topical 20% aluminum chloride hexahydrate in absolute anhydrous ethyl alcohol, available as Driclor, may reduce hyperhidrosis and odor, but the pits remain. The solution is applied at night, allowed to dry, and washed off the following day. Initially it should be used daily until the condition is brought under control, when it can be used less frequently. The use of 20% aluminum chloride hexahydrate for palmoplantar hyperhidrosis has not been as successful as its use for axillary hyperhidrosis. Topical 4% formaldehyde solution applied with gauze soaks as the patient sits or stands with their feet on the gauze in a bowl for 10 to 15 minutes once or twice daily reduces the hyperhidrosis. Alternatively, immersion of the soles of the feet in 5% formaldehyde may be utilized. Formalin ointment 40% has been used with some success but is not commercially available in the UK.

Topical 2% glutaraldehyde has been reported to have good therapeutic results in PK but sometimes the patient may require the 10% strength to reduce hyperhidrosis. Glutaraldehyde is available in the UK as Cidex (25% or 50% strength), which is used for instrument sterilization, and is somewhat hazardous to handle. Like formaldehyde, glutaraldehyde may cause contact sensitization, but it does not cross-react with formaldehyde.

Iontophoresis is frequently used in palmar and plantar hyperhidrosis and can be used in the treatment of PK. Botulinum toxin has also been used. Oral anticholinergics are perhaps excessive.

Various other agents have been tried topically but with limited success. These include 0.1% triamcinolone acetonide once or twice daily, iodochlorhydroxyquin-hydrocortisone cream (vioform-hydrocortisone) once or twice daily, flexible collodion, Whitfield ointment (6% benzoic and 3% salicylic acid ointment in a petrolatum base) twice daily, and Castellani paint. Water-repellant silicone ointment has been found not to significantly improve PK.

Specific investigations