Pitted keratolysis resulting from hyperhidrosis case study

Clinical diagnosis and treatment options for pitted keratolysis.

Extensive PK on moist, macerated skin
Extensive PK on moist, macerated skin

The case

This 36-year-old man had a history of severe hyperhidrosis affecting his hands and feet. He was otherwise well and taking no medication. The hyperhidrosis was causing maceration of his plantar skin. He had tried talc and topical antiperspirants, with no benefit. Examination revealed severe extensive pitted keratolysis (PK) on a background of moist, macerated skin. The PK did not concern him, but he was referred for a course of botulinum toxin injections to reduce the hyperhidrosis.

Pitted keratolysis

PK is a common superficial bacterial skin infection characterised by typical multifocal, discrete, crateriform pitting and superficial erosions. PK lesions are pits in the stratum corneum of 1mm to 7mm diameter, which can become confluent to form craters, sulci or irregular erosions. PK typically affects the pressure-bearing surfaces of the feet, including the toes, ball of the foot and heel. It rarely affects non pressure-bearing areas.1,2

PK may be asymptomatic, but can cause itching, malodour and embarrassment sufficient to affect quality of life. The diagnosis is made clinically. Microbiology tests are rarely needed, although skin scrapings are occasionally taken, to exclude fungal infections.

Several types of bacteria, including corynebacteria, actinomyces and streptomyces, can cause PK. In cases of hyperhidrosis, increased skin surface pH or skin occlusion, these bacteria proliferate and produce protease enzymes that digest keratin in the stratum corneum, causing pits.3

Men are affected more frequently than women. Predisposing factors include warm, humid environments, occlusive footwear, keratoderma, diabetes mellitus, immunodeficiency and advanced age. Military personnel, farmers, industrial workers and athletes are particularly affected.4 Patients with primary hyperhidrosis have significantly more PK than controls.5

Treatments for PK include topical antibiotics, such as erythromycin, clindamycin, mupirocin and fusidic acid. Oral erythromycin is effective in severe disease. Topical corticosteroids, benzoyl peroxide and salicylic acid ointment, and formaldehyde solution have been used with varying success.6 A combination of benzoyl peroxide with a topical antibiotic is more effective than monotherapy.7

Patients should wear cotton or wool socks to absorb sweat, expose the skin to the air when possible, wash daily with antibacterial products, allow wet shoes to dry before wearing and apply antiperspirant or talc to the feet.


Primary (focal) hyperhidrosis affects the axillae, palms, soles or craniofacial region. Plantar hyperhidrosis is sweating from the feet beyond what is physiologically appropriate. It usually begins in childhood or adolescence and can lead to sweat dripping off the feet, which makes wearing certain shoes difficult. It can cause malodour, fungal infections and PK.8

The diagnosis is made on a typical history in the absence of systemic symptoms. The cause of plantar hyperhidrosis is not well understood. Most cases are sporadic, although there are reports of familial palmoplantar hyperhidrosis.9

Men and women are equally affected and the prevalence is approximately 2.8% in the US population, but this may be an underestimate because of patients’ embarrassment about the condition.10 Palmoplantar hyperhidrosis occurs 20 times more frequently in Japanese people than any other ethnic group.9

Palmoplantar hyperhidrosis can severely affect relationships, leisure activities, personal hygiene, work and self-esteem.11

Management of plantar hyperhidrosis can be difficult because treatments are not usually curative and are often limited by side-effects.12

Topical aluminium chloride antiperspirants are the first option, but the more potent versions can irritate the skin. Iontophoresis – the introduction of ions transdermally using an electrical current – can be used when antiperspirants fail. Patients buy their own machine for home use, but this treatment does not work in every case.

Antimuscarinic drugs can be effective, especially if several body sites are involved. Most patients experience side-effects, such as dry mouth, and less often, headaches, blurred vision and constipation. Propantheline bromide is licensed for this indication. Oxybutynin modified-release is a useful unlicensed product with the advantage of once-daily dosing.13

Beta-blockers only tend to be effective in patients where hyperhidrosis is closely related to anxiety.

Botulinum toxin A injections decrease the activity of the eccrine sweat glands. They take a few days to work and typically last three to six months. The main adverse effect is pain during the procedure.14

Lumbar sympathectomy involves ablation of sympathetic ganglia at L3/L4 and appears to treat plantar hyperhidrosis. Minimally invasive sympathectomy for the lumbar chain is a relatively new and effective technique. However, there is the potential for severe adverse effects, such as loss of sexual function.15 RCTs are needed to assess the safety and efficacy of this procedure.

  • Dr Maria-Angeliki Gkini is a clinical fellow and Dr Anshoo Sahota is consultant dermatologist at Whipps Cross University Hospital, Barts Health NHS Trust

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  1. Pranteda G, Carlesimo M, Pranteda G et al. Pitted keratolysis, erythromycin, and hyperhidrosis. Dermatol Ther 2014; 27: 101-4
  2. Takama H, Tamada Y, Yano K et al. Pitted keratolysis: clinical manifestations in 53 cases. Br J Dermatol 1997: 137: 282-5
  3. Holland KT, Marshall J, Taylor D. The effect of dilution rate and pH on biomass and proteinase production by Micrococcus sedentarius grown in continuous culture. J Appl Bacteriol 1992; 72: 429-34
  4. Van der Snoek EM, Ekkelenkamp M, Suykerbuyk JC. Pitted keratolysis; physicians’ treatment and their perceptions in Dutch army personnel. J Eur Acad Dermatol Venereol 2013; 27: 1120-6
  5. Walling H. Primary hyperhidrosis increases the risk of cutaneous infection: a case-control study of 387 patients. J Am Acad Dermatol 2009; 61: 242-6
  6. Singh G, Naik C. Pitted keratolysis. Indian J Dermatol Venereol Leprol 2005; 71: 213-15
  7. Vlahovic TC, Dunn SP, Kemp K. The use of a clindamycin 1%-benzoyl peroxide 5% topical gel in the treatment of pitted keratolysis: a novel therapy. Adv Skin Wound Care 2009; 22: 564-6
  8. Vlahovic TC. Plantar hyperhidrosis: an overview. Clin Podiatr Med Surg 2016; 33: 441-51
  9. Yamashita N, Tamada Y, Kawada M et al. Analysis of family history of palmoplantar hyperhidrosis in Japan. J Dermatol 2009; 36: 628-31
  10. Moraites E, Vaughn OA, Hill S. Incidence and prevalence of hyperhidrosis. Dermatol Clin 2014; 32: 457-65
  11. Hamm H. Impact of hyperhidrosis on quality of life and its assessment. Dermatol Clin 2014; 32: 467-76
  12. Singh S, Kaur S, Wilson P. Plantar hyperhidrosis: A review of current management. J Dermatolog Treat 2016; 6: 1-6
  13. Wolosker N, Teivelis MP, Krutman M et al. Long-term results of the use of oxybutynin for the treatment of plantar hyperhidrosis. Int J Dermatol 2015; 54: 605-11
  14. Weinberg T, Solish N, Murray C. Botulinum neurotoxin treatment of palmar and plantar hyperhidrosis. Dermatol Clin 2014; 32: 505-15
  15. Singh S, Kaur S, Wilson P. Early experience with endoscopic lumbar sympathectomy for plantar hyperhidrosis. Asian J Endosc Surg 2016; 9: 128-34

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