January 2019

Case: A Woman with Blistering, Erythema, and Scaling of the Feet

Figure 1. Blistering, erythema, and scaling of the patient’s soles.

What’s causing the worsening signs and symptoms that are eroding the patient’s quality of life? Once that question is answered, what treatment should be pursued?

By Carla Benson, DPM

In this case study, we describe the work-up and management of a woman whose illness was characterized by multiple vesicles and pustules and itching, scaling, and redness of the feet (as well as the hands), that progressed over months. For the audience of lower-extremity clinicians, we build a differential diagnosis that considers conditions that have a similar presentation and that affect the feet primarily.

CASE: Progressive itching, blistering, and scaling of the feet

Presentation. A 55-year-old Hispanic woman with a history of psoriasis and a 30 pack–year history of smoking comes to the clinic with a chief complaint of itching and scaling of the soles of the feet. She also reports pain in the feet of increasing severity over the past 3 months.

Initially, the patient says, she noticed a few small blisters; these progressed over several weeks to blistering, redness, and scaling (Figure 1). The pain and itching became so unbearable that she says she has trouble walking and difficulty sleeping. Similar symptoms on the palms of both hands (Figure 2) have affected her quality of life.

Physical examination. The vascular exam of the feet reveals slightly diminished circulation, with a decrease in pedal pulses and multiple varicosities bilaterally. Neurologic sensation is intact. Orthopedic exam reveals an antalgic gait.

Dermatologic exam reveals bilateral erythematous desquamation, multiple brownish macules, thin hyperkeratotic plaques, multiple symmetric pustules and serous-filled vesicles, and fissures plantarly and bilaterally. Pain on palpation of the plantar feet is also noted. Toe nails are positive for dystrophy.

Laboratory testing. A potassium hydroxide (KOH) prep and fungal culture of the feet are performed to rule out tinea pedis (see “Building the differential diagnosis,” below) and other potential fungal or candidal causes of the condition. All tests of the specimens are negative.

Building the Differential Diagnosis

Figure 2. Blistering of the patient’s palms.

Tinea pedis. Commonly known as athlete’s foot, tinea pedis is a dermatophytic condition usually caused Tinea rubrum and most commonly affecting the foot. Tinea pedis can cause hyperkeratosis with scaling of the plantar aspect of the foot, in what is known as a moccasin distribution; when caused by Trichophyton mentagrophytes, the condition also can appear interdigitally, leading to acute ulceration. Vesiculobullous-type tinea pedis is a condition in which interdigital vesicles develop and coalesce into bullae.

A diagnosis of tinea pedis is based on the clinical presentation and, in more complicated cases, a positive KOH prep.1 Depending on the severity of symptoms, treatment is a topical or oral antifungal.

Rule in or rule out? In the case we present here, the fact that the KOH prep test was negative and the lesions appeared on the feet and hands makes a diagnosis of tinea pedis less likely. Rule out.

Acute contact dermatitis. This inflammatory condition of the skin occurs secondary to a cell-mediated response following exposure to an irritant or potential allergen. A type-IV delayed cell-mediated hypersensitivity reaction occurs in 2 phases: sensitization to the antigen followed by an allergic response following re-exposure to that antigen.2 The antigen or the allergen can be a small amount of soap, shampoo, nail polish, or practically anything else the patient comes in contact with.

Acute contact dermatitis presents as erythematous, scaling, pruritic skin. The condition can worsen to vesicles, bullae, and ulceration. A patch test, in which the skin in exposed to various antigens and allergens (which are then immediately removed), along with clinical evaluation, are useful in diagnosing this condition. Topical corticosteroids and systemic antihistamines can be administered to help with the accompanying pruritus.

Rule in or rule out? Based on the distribution, pervasiveness, and symmetry of our patient’s symptoms, acute contact dermatitis is not a candidate diagnosis. Rule out.

Pompholyx, also known as dishydrodic eczema and acute palmoplantar eczema, affects primarily the palmoplantar aspects of the hand and feet. The disorder can produce a vesiculo- bullous eruption, generally on the lateral aspect of the hands and feet, with intense pruritus. Vesicles and bulllae usually persist for weeks, subsequently drying out and resolving as desquamation. Although pustules can be present, they are generally a secondary sequelae of an infection and not the primary manifestation of the condition. The majority of cases generally affects the hands. The primary manifestation is usually ill-defined erythematous lesions with desquamation.

Diagnosis is usually made through clinical evaluation; however, a skin biopsy can be helpful in differentiating conditions in difficult cases and seemingly similar appearing pathologies. This condition is usually treated with topical or systemic corticosteroids.

Rule in or rule out? The pustules seen on our patient’s feet transitioned to brownish macules in approximately 8 days, which is inconsistent with the longer, multi-week course of pomphylox. Rule out.

Palmoplantar plaque psoriasis. Psoriasis is a chronic inflammatory condition with many subtypes. Psoriasis has a very low prevalence in adults and in children worldwide.3 Palmoplantar plaque psoriasis is a psoriatic variant that affects mostly the hands and feet. The patient generally presents with an erythematous base with sharply demarcated, silvery, scaly plaques. Although plaques are present in our patient, pustules do not occur.4 A periodic acid Schiff-diastase stain can be used as a diagnostic tool in cases where a history and physical is inconclusive. This stain will be able to more conclusively differentiate between psoriasis and a fungal infection.

Rule in or rule out? Our patient has pustules, which are not part of the presentation of palmoplantar plaque psoriasis. Rule out.

Palmoplantar pustulosis (PPP) is characterized by crops of sterile pustules on the plantar aspect of the hands and feet that erupt over time). In 8 to 10 days, pustules usually evolve to brownish macules surrounded by scaling and erythema. The pustules are generally intensely pruritic and can  cause a burning sensation. Thick hyperkeratotic plaques are usually present, producing a psoriatic-like appearance.

Palmoplantar pustulosis has a much higher predominance in females. Precipitating risk factors include smoking, viral and bacterial infection, metal sensitivity, psychological stress, and various medications.

The diagnosis of PPP can generally be made solely on the basis of the history and physical. A review of symptoms should be performed, including any potential association with joint disease, a thyroid abnormality, or gluten sensitivity; these conditions often exist concomitantly. Additional testing, such as a KOH prep, might be useful in ruling out cutaneous fungal infections; skin biopsy can help identify any histopathologic abnormalities in refractory cases.

Rule in or rule out? Based on the presentation, the patient is given a diagnosis of PPP. Her history of smoking, psoriasis, female gender, and clinical findings of pustules on the soles of the feet and palms of the hands lead to this conclusion.3 The negative KOH prep helped rule out various other fungal causes.

The relationship between PPP and psoriasis is controversial

Some experts think that PPP is a variant of psoriasis; others hold that the disorder is a distinct entity5 (although patients with psoriasis do have a higher predilection for PPP). Clinical similarities exist between psoriasis and PPP: scaling plaques, an erythematous base, and pruritus. There are also demographic similarities between the 2 diseases: age of onset, family history of psoriasis, duration of the disease, comorbidities, and smoking status.6 The 2 diseases share histologic similarities: neutrophil dysfunction and findings on specific serum studies, including eosinophilic cationic protein elevations and other chemokinetic effects.

Palmoplantar pustulosis and psoriasis do have different genetic markers: In PPP, the psoriasis susceptibility PSORS1 locus is absent, and an association with the interleukin-36 receptor agonist mutation (not seen in psoriasis) is common. There also appears to be a common genetic linkage between PPP and SAPHO disorder (synovitis, acne, palmoplantar pustulosis, hyperostosis, and osteitis), which is not associated with psoriasis.

CASE: Treatment and Resolution

The patient is counseled on smoking cessation. She is given a 4-week course of 0.05% clobetasol propionate cream under occlusive dressings, after which symptoms resolve.7 Subsequently, she is lost to follow-up.

Principles of PPP Management

First-line treatment of PPP includes topical corticosteroids, oral retinoids, and photochemotherapy. Studies have shown the efficacy of super-high-potency corticosteroids under occlusion for a maximum of 4 weeks in cases of focal involvement.8 Within 2 weeks, symptoms usually resolve. If, after 4 weeks, symptoms persist, however, an oral retinoid or photochemotherapy should be instituted. For more diffuse cases, a regimen of either an oral retinoid, such as acitretin, or psoralen plus ultraviolet A photochemotherapy is recommended.

Second-line treatment of refractory disease is the combination of an oral retinoid and oral or topical psoralen plus ultraviolet A photochemotherapy, known as RePUVA. Immunotherapy with cyclosporine or methotrexate can also be initiated.

Summing up

It is important for clinicians who specialize in the care of the lower extremity to be aware of PPP and be able diagnosis it accurately. Proper treatment, including strategies for addressing refractory disease, can then significantly improve the quality of a patient’s daily life.

Carla Benson is a podiatrist in Teaneck, New Jersey.

REFERENCES
  1. Al Hasan M, Fitzgerald SM, Saoudian M, et al.. Dermatology for the practicing allergist: Tinea pedis and its complications. Clin Mol Allergy. 2004;2(1):5.
  2. Vlahovic TC. Keys to diagnosing and treating contact dermatitis. Podiatry Today. 2016;29(10):54-59.
  3. Bilal J, Malik SU, Riaz IB, et al. Psoriasis and psoriatic spectrum disease: a primer for the primary care physician. Am J Med. 2018;131(10):1146-1154.
  4. Benjegerdes KE, Hyde K Kivelevitch D, et al. Pustular psoriasis: pathophysiology and current treatment perspectives. Psoriasis (Auckl). 2016;6:131-144.
  5. Ammoury A, El Sayed F, Dhaybi R, et al. Palmoplantar pustulosis should not be considered as a variant of psoriasis. J Eur Acad Dermatol Venereol. 2008;22(3):392-393.
  6. Brunasso AM, Puntoni M, Aberer W, et al. Clinical and epidemiological comparison of patients affected by palmoplantar plaque psoriasis and palmoplantar pustulosis: a case series study. Br J Dermatol. 2013;168(6):1243-1251.
  7. Michaëlsson G, Gustafsson K, Hagforsen E. The psoriasis variant palmoplantar pustulosis can be improved after cessation of smoking. J Am Acad Dermatol. 2006;54(4):737-738.
  8. Marsland AM, Chalmers RJ, Hollis S, et al. Interventions for chronic palmoplantar pustulosis. Cochrane Database Syst Rev. 2009(l):CD001433.
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