What’s Causing the Malodorous, Painful Rash on This Marine’s Heels?

AUTHORS:
Robert J. Long, MD, and Johannah Valentine, MD

CITATION:
Long RJ, Valentine J. What’s causing the malodorous, painful rash on this marine’s heels? Consultant. 2016;56(10):918.

DISCLOSURE: 
The views expressed herein are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, the Department of Defense, or the US Government.

A 27-year-old US Marine Corps ordnance handler presented with pain and a rash on his soles that had been present for 4 months while he was deployed aboard an aircraft carrier in the north Arabian Sea.

He reported burning and stabbing pain while walking, which was severe enough to limit his work on the flight deck. Additionally, he noted increased sweating and a foul foot odor. He reported that he had developed this same condition on a previous deployment, and that it had been refractory to treatment with topical and oral antifungals.

On physical examination, the patient exhibited multiple white depressions and pits on the soles ranging from 1 to 10 mm in size (Figures). These crateriform pitting lesions involved the pressure-bearing areas of his heels bilaterally and were tender to palpation. Some areas appeared to be eroded to the dermis. The feet had strong foot odor with additional sulfur character.

What’s the diagnosis of this Marine’s foot condition?

1. Pitted keratolysis
2. Tinea pedis
3. Plantar warts
4. Nevoid basal cell carcinoma syndrome

Answer and discussion on next page

Answer: Pitted Keratolysis

The patient received a clinical diagnosis of pitted keratolysis (PK) and was started on topical clindamycin and a benzoyl peroxide wash applied to the affected area twice daily. Within 1 week, the pain had greatly improved. At 2 weeks, the size and the depth of the pits had been noticeably reduced. After 1 month, there had been a near complete resolution of the lesions. The initial treatment lasted a total of 4 weeks. One month after cessation of the initial treatment, the pits recurred, but they resolved following an additional week of treatment, with no reappearance.

Pathogenesis

PK is a common superficial bacterial skin disorder characterized by crateriform pitting on the plantar surfaces in pressure-bearing locations.^1,2 Pathogens attributed to this cutaneous infection include Kytococcus sedentarius, Dermatophilus congolensis, Corynebacterium species, Actinomyces species, and Streptomyces species.^3-5 Potential factors predisposing to PK include hyperhidrosis, prolonged occlusion, and increased skin surface pH.^2,5 In the presence of these conditions, pathogenic bacteria proliferate and produce proteinases, which create pits as they degrade through the stratum corneum. The common malodor of PK is presumed to be the production of sulfur-compound byproducts such as thiols, sulfides, and thioesters.⁶

Epidemiology

PK occurs worldwide in both tropical and temperate environments and has a strong association with military occupations, boot-wearing professions, and homelessness.^1,2,7,8 Primary hyperhidrosis is the only concurrent condition associated with a significant increase in the occurrence of PK.⁹ The high prevalence in military personnel is attributable to long-term occlusive boot-wearing combined with hot and humid environments. No studies have found any association of PK incidence with age, gender, or race.^2,8

Clinical manifestations

A patient’s clinical presentation and the characteristic odor are usually adequate to diagnose PK, thus skin biopsies are usually not required. However, if a biopsy is performed, findings may include craterlike depressions limited to the stratum corneum, mild dermal inflammatory reaction, and filamentous bacteria limited to the area of the depression.¹⁰ Patients may also present with sliminess, itching, and foot pain, and disability can occur when the skin becomes deeply denuded.^1,2,8

Given the mildly symptomatic nature of PK, individuals may live with this condition for years believing that the odor, sweating, and skin appearance is normal.² PK can last for many years if untreated, exhibiting spontaneous episodes of exacerbations and remissions.¹¹

Diagnosis and differential diagnosis

PK is often misdiagnosed as tinea pedis, plantar warts, nevoid basal cell carcinoma syndrome, and keratolysis exfoliativa. It is not unusual for a patient with PK to unintentionally aggravate the condition with self-treatment with over-the-counter products prior to seeking care. Misdiagnosis and mistreatment is common, likely from the lack of general knowledge about the condition.²

Treatment and prognosis

Based on historical practices, treatment of PK can be relatively simple, safe, and cost-effective, with clearance in 3 to 4 weeks.^1,11 Suggested treatments include topical antibiotics, antimicrobial washes, and treatment of excess sweating. Twice-daily applications of topical erythromycin, clindamycin, or mupirocin have been effective.^1,2,11,12

Targeting hyperhidrosis is key in treating PK and preventing reoccurrence. This can be accomplished with the use of foot powder, topical antiperspirant such as aluminum chloride 25%, or injections of botulinum toxin in severe cases.^13,14 Other strategies include avoiding occlusive footwear, using wool socks to wick moisture away from the skin, and wearing properly fitted footwear to avoid friction. Clearance of PK lesions may be more challenging in occupations that require the use of boots in hot environments.^2,8

Robert J. Long, MD, is a lieutenant and flight surgeon with the Marine Fighter Attack Squadron 251 at Marine Corps Air Station Beaufort, South Carolina.

Johannah Valentine, MD, is a lieutenant commander and a dermatologist at Naval Medical Center San Diego, California.

References:

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