A Heavy Smoker With Asymptomatic Pustules on the Palms and Soles

Citation:
Leung AKC, Barankin B. A heavy smoker with asymptomatic pustules on the palms and soles. Consultant. 2016;56(12):1104-1107.

A 50-year-old white man presented with recurrent eruptions of asymptomatic pustules on his palms and feet for the past 3 years. 

He had been smoking more than 20 cigarettes a day for the past 3 decades. His medical history was unremarkable. There was no family history of skin disorders. His 16-year-old daughter has Hashimoto thyroiditis.

Physical examination revealed an erythematous base with hyperkeratotic areas, mixed with numerous scattered pustules in various stages on the soles and palms. He did not have pitting of the nails or other signs of psoriasis. The rest of the physical examination findings were unremarkable.

Answer on next page.

Answer: D. Palmoplantar pustulosis

A diagnosis of palmoplantar pustulosis was made by the patient’s dermatologist. He was advised to discontinue smoking for this and other health benefits, and he was prescribed oral acitretin 25 mg and topical clobetasol twice daily, which provided marked improvement at a 2-month follow-up visit.

OVERVIEW

Palmoplantar pustulosis, also known as pustulosis palmoplantaris and pustulosis palmaris et plantaris, is a chronic inflammatory skin disease characterized by recurrent sterile pustular eruptions on the palms and soles, usually on an erythematous base.¹ The condition was first described by Barber in 1930 as a subtype of psoriasis (localized palmoplantar pustulosis).² It was reclassified as a separate entity in 2007 by the International Psoriasis Council.³

Classification

There is some debate about whether palmoplantar pustulosis is a variant of psoriasis or a disease of its own. Some authors believe that palmoplantar pustulosis is a variant of psoriasis, given that 2% to 24% of patients with palmoplantar pustulosis have evidence of psoriasis on other parts of the body, that 10% to 43% of patients with palmoplantar pustulosis have family members with psoriasis, and that the histology of the 2 conditions is indistinguishable.^4-6 In contrast, most other authors consider palmoplantar pustulosis as a distinct disease entity, given that its genetic characteristics are different from those of psoriasis; that it has a strong association with smoking; that there is a lower frequency of family history of psoriasis in patients with palmoplantar pustulosis compared with patients with psoriasis; and that palmoplantar pustulosis has a female predominance, an older age of onset, and differences in patient’s response to therapy.^3,6-8

Epidemiology

Estimates of the prevalence of palmoplantar pustulosis range from 0.01% to 0.05% in Western countries.^4,9,10 On the other hand, the prevalence is estimated to be 0.12% in Japan.¹¹ The condition is most common in the fifth and sixth decade of life.^8,12,13 The female to male ratio is 3 to 1.^8,12,13 The occurrence is usually sporadic.

Etiopathogenesis

The exact etiopathogenesis is not fully understood. Tobacco consumption and focal infections (eg, tonsillitis, dental infection, chronic sinusitis) have been proposed as central triggers, through an immune reaction to external antigens that display features of autoreactivity in genetically predisposed individuals.^1,8,14 The acrosyringium seems to be the main target for the inflammation.^13,15,16 It has been shown that both α7 nicotinic acetylcholine receptors and choline acetyltransferase are unregulated in neutrophils and mast cells in lesional skin by smoking.¹⁶ Studies have also shown that tonsillar lymphocytes formed in the setting of tonsillitis are responsible for the release of cytokines, and that such cytokines are responsible for accumulation of neutrophils in lesional skin.¹⁴ Genomic studies have identified variations of interleukin-19, -20, and -24 genes that increase the risk for palmoplantar pustulosis.^1,14 

Other predisposing factors include rituximab use, emotional stress, trauma, and allergic contact dermatitis to nickel.^14,17 Paradoxically, tumor necrosis factor α inhibitor therapy may trigger new-onset palmoplantar pustulosis or worsen existing palmoplantar pustulosis.¹²

Histopathology

Histologic examination shows epidermal sterile pustules filled with neutrophils and eosinophils, accumulation of mast cells and eosinophils below pustules, infiltration of inflammatory cells in the dermis, loss of granular layer, parakeratosis, psoriasiform epidermal hyperplasia, and clubbing and anatomising of the rete ridges.^1,14,18

Clinical Manifestations

Typically, palmoplantar pustulosis presents as recurrent crops of sterile pustules occurring on one or both hands and/or feet. The involvement is often symmetric but sometimes is unilateral.¹ The pustules often coalesce and resolve over a few days, leaving brown macules and hyperkeratosis.¹ Erythema, scale, and desquamation often surround the sites of pustulation.¹ In the more persistent stage, the disease is characterized by brown macules (remnants of resolving pustules) and erythematous, hyperkeratotic, desquamative plaques.¹ Cracks and deep fissures may be present. Though rare, the Koebner phenomenon associated with palmoplantar pustulosis has been reported.¹⁹ Patients with palmoplantar pustulosis may experience pruritus, a burning sensation, and pain in the affected area.

Diagnosis and Differential Diagnosis

The diagnosis is usually clinical, based on the characteristic features. A potassium hydroxide wet-mount examination of skin scrapings should be performed if a fungal infection is suspected. A referral to a dermatologist or skin biopsy can be considered if the diagnosis is in doubt.

The differential diagnosis includes dyshidrotic eczema (pompholyx), pustular psoriasis, tinea pedis/tinea manuum, acrodermatitis continua of Hallopeau (acropustulosis), and streptobacillosis.^18,20

Complications

Palmoplantar pustulosis has a significant negative impact on the quality of life. The discomfort resulting from this condition can be considerable. In severe cases, painful fissuring may interfere with work, walking, and leisure activities.¹³ Patients with palmoplantar pustulosis are at risk for autoimmune thyroid disease, gluten sensitivity, SAPHO syndrome (synovitis, acne, pustulosis, hyperostosis, and osteitis), dyslipidemia, ischemic heart disease, anxiety, and depression.^8,12,13,16

Prognosis and Management

The disease tends to run a chronic course with frequent exacerbations and partial remissions.¹

The condition is notoriously difficult to treat. Precipitating and exacerbating factors should be minimized or avoided. If the patient is a smoker, cessation of smoking is strongly advised.

Hydration of the skin is of paramount importance. Liberal use of moisturizers should be strongly encouraged. Super-high-potency topical corticosteroids applied under occlusion are the mainstay of therapy.^12,21 For more stubborn or diffuse cases, oral retinoids and/or phototherapy should be considered.^6,21,22 In severe or resistant cases, methotrexate, cyclosporine, mycophenolate, tetracycline, and biologic agents may be tried.^21,23 

Preliminary studies have shown that some patients with palmoplantar pustulosis associated with recurrent tonsillitis may benefit from tonsillectomy.^14,16,24 Future studies are necessary to identify which patients are likely to benefit from this procedure.

Alexander K. C. Leung, MD, is clinical professor of pediatrics at the University of Calgary and a pediatric consultant at the Alberta Children’s Hospital in Calgary, Alberta, Canada.

Benjamin Barankin, MD, is a dermatologist and the medical director and founder of the Toronto Dermatology Centre in Toronto, Ontario, Canada.

REFERENCES:

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