An itchy rash on a man's hand - Clinical Advisor

An itchy rash on a man’s hand

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A 37-year-old man without a significant past medical history presents to the dermatology clinic with an itchy rash on his right hand that he has had for about 4 months. He had tried numerous over-the-counter hand creams and hydrocortisone cream with no improvement. Additional questioning revealed a 1-year-history of dry, itchy feet. As a construction worker, he wears occlusive, steel-toed work boots and often wears gloves. He is also right-handed. Examination of his hands reveals a normal left hand and a scaly right palm. Diffuse, fine, dry white scale was present on the plantar aspect of both feet.

Microscopic examination of skin scrapings from his hand and one foot, using a potassium hydroxide (KOH) preparation, demonstrated branching hyphae, confirming the suspected diagnosis of two feet-one hand (2F1H) disease. Two feet-one hand disease is a superficial fungal infection that simultaneously...

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Microscopic examination of skin scrapings from his hand and one foot, using a potassium hydroxide (KOH) preparation, demonstrated branching hyphae, confirming the suspected diagnosis of two feet-one hand (2F1H) disease. 

Two feet-one hand disease is a superficial fungal infection that simultaneously affects both feet (bilateral tinea pedis) and one hand (unilateral tinea manuum); curiously, the other hand is uniformly spared. As with most superficial fungal infections affecting nonmucosal surfaces, the culprit organism is a dermatophyte. Although various genre of dermatophytes cause different skin conditions, the most common dermatophyte to cause 2F1H is a Trichophyton (T), specifically T rubrum.1 Molecular studies, when performed, have demonstrated that strains of T rubrum isolated from the hand and feet are identical.2 The initial infection is usually tinea pedis; tinea manuum tends to develop subsequently.

The lifetime risk in the general population for any type of dermatophytosis is 10% to 20%.3 Some patients may have a genetic predisposition for infection with T rubrum,4 and others have a significant comorbidity such as diabetes mellitus or an immune-suppressed state that predisposes them to fungal infections in general.5 However, 2F1H tends to be more common in Caucasian men independent of these known predisposing conditions.5 Although there is no significant relationship between handedness and the development of tinea in the dominant hand, 2H1F is more likely to develop in persons who have occupations that require frequent use of their hands.5

Coexistence of toenail dermatophytosis may be a predisposing factor for 2F1H. In a prospective study by Szepietowski et al, 42.8% of patients with toenail onychomycosis had a concomitant fungal skin infection, with tinea pedis being the most common at 33.8%.6 Although toenail onychomycosis can be caused by a variety of pathogenic fungi, dermatophytes are the most common cause, with the single most common pathogen being T rubrum.7 In this scenario, one typically finds the affected toenail(s) to have thickening of the distal aspect of the nail plate, which is typically soft and more brittle, overlying a collection of subungal debris.

The diagnosis of 2F1H is often suspected given the unusual clinical presentation. However, confirmatory tests are needed. An easy, in-clinic test is the microscopic evaluation of skin scrapings of scale from the feet and the affected hand using the standard KOH preparation. Properly done, and with a skilled eye, one will see the classic branching hyphae of the dermatophyte culprit in each specimen. If this technique is not available, or negative, a culture of the scrapings should be done. The culture should be specific for a dermatophyte in this particular clinical scenario; exactly how this is ordered varies in practice. 

Several clinical entities may mimic 2F1H and should be considered in the differential diagnosis; some of these include keratolysis exfoliativa, dyshidrotic eczema, an id reaction, and palmar plantar pustulosis. However, careful evaluation and appropriate testing will subsequently be diagnostic. 

Keratolysis exfoliativa is an idiopathic disorder of patchy peeling of the palms, soles, or both, most commonly associated with hyperhidrosis, and more common in summer. Fungal studies will be negative. 

Dyshidrotic eczema typically presents with pruritic vesicles/bullae on the palms, sides of fingers, and/or soles; scaling and redness are associated with rupture of the vesicles. Outbreaks are episodic and may last for several weeks. Dyshidrotic eczema tends to be associated with contact irritants or allergens, not fungal infections, and many patients are atopic.8 

An id reaction, otherwise referred to as an auto-eczematous reaction, is an acute, immunologically mediated skin reaction to a variety of cutaneous stimuli including inflammatory and infectious disorders. The eruption may be generalized or localized to the hands, mimicking dyshidrotic eczema. When associated with a dermatophyte infection, most commonly tinea pedis, the condition is referred to as a dermatophytid. Dermatophytids typically affect both hands, not just one; although studies from the feet will demonstrate fungi, those from the hands will not. The treatment in this setting is to treat the coexistent tinea pedis.

As the name would suggest, palmoplantar pustulosis (PPP) is a chronic condition affecting the palms and soles. Patients develop small sterile pustules and plaques; pruritus is a common symptom, and if the plaques fissure they may be painful. Clinically, it may be difficult to distinguish PPP from dyshidrotic eczema or a dermatophyte id. However, unlike either of these conditions, PPP is not associated with atopy or tinea. Although PPP may be idiopathic, it is often considered a variant of psoriasis; it is more common in women and in those who smoke. Evaluation should include an assessment for other signs/symptoms of psoriasis including nail changes and arthritis. 

For many patients with 2F1H, topical antifungal therapy is adequate therapy. Patients should be advised to use the topical antifungal until the condition is fully resolved, which may take several weeks. The antifungal cream should be applied between the toes, as well as all over the palms and soles. As azoles are fungistatic, an allyamine may be more effective since it is fungicidal.9 Concomitant use of a topical keratolytic containing lactic acid or urea may be synergistic as it dissolves the keratin necessary for dermatophyte sustenance. 

Systemic treatment should be considered only when topical therapy fails, or when there is a proven co-existent nail infection that warrants treatment. Itraconazole, fluconazole, and terbinafine are the most commonly prescribed oral antifungals for dermatophyte infections. Treatment courses vary and range from 1 week to 3 months, dictated by skin-only, or concomitant skin and nail infection. The decision to use an oral antifungal agent should not be taken lightly since a patient’s comorbidities and use of other medications may heighten adverse drug reactions. 

Recurrence of 2F1H is common, especially in the setting of onychomycosis. Patients should be advised that routine use of antifungal therapy on their feet is needed to prevent/manage tinea pedis and prevent the redevelopment of hand involvement once cleared. 

The rash on our patient resolved after 3 weeks of using topical terbinafine and topical lactic acid cream twice daily. He continues to apply terbinafine to his feet to prevent recurrence.

Michelle Vy is a 4th-year medical student, and Julia Nunley, MD, is a professor of dermatology and program director of dermatology at the Medical College of Virginia Hospitals of Virginia Commonwealth University in Richmond.

References

  1. Seeburger J, Scher RK. Long-term remission of two feet-one hand syndrome. Cutis. 1998;61:149-151. 
  2. Zaias N, Tosti A, Rebell G, Morelli R, Bardazzi F, Bieley H. Autosomal dominant pattern of distal subungual onychomycosis caused by Trichophyton rubrum. J Am Acad Dermatol. 1996;34(2 Pt 1):302-304. 
  3. Drake LA, Dinehart SM, Farmer ER, et al. Guidelines of care for superficial mycotic infections of the skin: tinea corporis, tinea cruris, tinea faciei, tinea manuum, and tinea pedis. J Am Acad Dermatol. 1996;34 (2 Pt 1):282-286.
  4. Korting HC, Tietz HJ, Brautigam M, Mayser P, Rapatz G, Paul C. One week terbinafine 1% cream (Lamisil) once daily is effective in the treatment of interdigital tinea pedis: a vehicle controlled study. LAS-INT-06 Study Group. Med Mycol. 2001;39:335-340. 
  5. Daniel CR, Gupta AK, Daniel MP, Daniel CM. Two feet-one hand syndrome: a retrospective multicenter survey. Int. J. Dermatol. 2008;36:658-660. 
  6. Szepietowski JC, Reich A, Garlowska E, Kulig M, Baran E. Factors influencing coexistence of toenail onychomycosis with tinea pedis and other dermatomycoses: a survey of 2761 patients. Arch Dermatol. 2006;142:1279-1284. 
  7. Scher RK, Tavakkol A, Sigurgeirsson B, et al. Onychomycosis: diagnosis and definition of cure. J Am Acad Dermatol. 2007;56:939-944.
  8. Wollina U. Pompholyx: a review of clinical features, differential diagnosis, and management. Am J Clin Dermatol. 2010;11:305-314.
  9. Korting HC, Kiencke P, Nelles S, Rychlik R. Comparable efficacy and safety of various topical formulations of terbinafine in tinea pedis irrespective of the treatment regimen: results of meta-analysis. Am J Clin Dermatol. 2007;8:357-364. 
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