Derm Dx: Painful, Recurrent Rash on the Fingers

Acrodermatitis Continua of HallopeauAcrodermatitis continua of Hallopeau (ACH) is a chronic eruption of painful, sterile pustules on the distal fingers or toes. Named after the French dermatologist Francois Hallopeau, who was one of the first to characterize the disease in...

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Acrodermatitis Continua of Hallopeau

Acrodermatitis continua of Hallopeau (ACH) is a chronic eruption of painful, sterile pustules on the distal fingers or toes. Named after the French dermatologist Francois Hallopeau, who was one of the first to characterize the disease in 1890, ACH has gone by several other names including dermatitis repens, acrodermatitis perstans, and acropustulosis.^1,2 Although infectious, neural, and inflammatory etiologies were initially proposed, it was only first associated with pustular psoriasis in 1925.³ Since then, it has been definitively shown that ACH is a rare acropustular variant of pustular psoriasis.³

ACH is an uncommon form of pustular psoriasis, which makes robust epidemiologic studies difficult to conduct. Typically, the disease initially presents in a single digit rather than multiple and in the fingers more often than the toes.⁴ ACH is most often seen in middle-aged women and is associated with other varieties of psoriasis and autoimmune conditions. Additional risk factors are difficult to describe due to the low number of reported cases; however, risk factors for pustular psoriasis in general include smoking, psychological stress, trauma, medications, and infection.⁵

Clinical presentation of ACH is characterized by acute episodes of progressive, painful pustule formation under and surrounding the nail plate associated with erythematous and scaly skin.⁶ Initially, a painful psoriasiform plaque develops around the nail fold. Small pustules then develop from the site of inflammation, and with time these often coalesce into larger lakes of pus. When these lesions burst, a shiny, erythematous bed is revealed where the cycle of pustule formation begins again. The lesions usually arise from the distal digit and tend to slowly spread proximally; depending on the phase of the disease, the lesions may appear moist and erythematous or crusted with small pustules underneath. ACH can also remain distally in 1 or more digits for many years without spreading. The nail fold and nail bed are often involved, leading to nail matrix destruction. In persistent cases, these eruptions may lead to severe atrophy, onychodystrophy, or osteolysis. Mucous membranes such as the oral mucosa, tongue, conjunctiva, and urethra may be affected in ACH as well.^6-8

Histologically, ACH is distinguished by the presence of subcorneal spongiform pustules with neutrophilic infiltration, which is typical for pustular psoriasis. These features are present on biopsy of the epidermis and nail bed, where marked acanthosis is often noted. Dermal changes are notable for lymphocytic inflammatory infiltrate and dilated vessels. In severe, chronic cases, there can be extreme thinning of the dermis and epidermis. Cultures of pustular fluid are typically sterile; however, secondary infection can occur and a positive culture should not rule out the diagnosis of ACH.⁹

The differential diagnosis of ACH can be quite broad depending on the time of diagnosis. In early stages, ACH can be easily confused for herpetic whitlow, paronychia, or acute contact dermatitis (ACD). Unlike ACH, paronychia does not typically have a relapsing course. ACH may be distinguished from ACD because ACD lesions are usually vesicular, not pustular.⁶ In children with evidence of subungual hyperkeratosis and inflammatory rash, parakeratosis pustulosa should be considered.⁵ Although in an atypical location, squamous cell carcinoma may appear similar to later lesions of ACH; the two can be differentiated by histopathology. Other lesions within this spectrum of pustular psoriasis include palmoplantar pustular psoriasis, generalized pustular psoriasis, and drug-induced acute exanthematous generalized pustular eruption. All of these conditions may be differentiated from ACH based on the location of the lesions.¹⁰

Diagnosis of ACH is largely based on the acute clinical presentation, reported progression of disease, and biopsy results. Gram stain smear, potassium hydroxide preparation, and culture of the pustules are necessary for diagnosis.⁸ When differentiating varieties of pustular psoriasis, genetic testing may play a role in diagnostics.¹⁰

Evidence-based treatment guidelines have been limited due to the rare nature of this disease; however, a variety of therapies have been attempted. Topical treatments such as vitamin A and D derivatives, tacrolimus ointment, corticosteroids, and 5-fluorouracil cream have been used with mixed results.⁸ There has been documented success with corticosteroid injections into the lateral or proximal nail folds for nail bed and nail matrix disease, respectively.⁶ There have also been multiple reports of successful ACH treatment with phototherapy. Systemic therapy with methotrexate, cyclosporine, and photochemotherapy as well as tumor necrosis factor blockers, infliximab, adalimumab, and etanercept have also been reported to be successful.⁸ Further investigation is required in order to define standard recommendation for treatment. However, ACH is often refractory to treatment and may eventually destroy the nail bed and underlying bone.

The patient described in this case was treated with combination calcipotriol and betamethasone dipropionate ointment applied twice daily for 1 month. At follow-up, the erythema and pustules were noted to be resolved, but there were no improvements to the dystrophic nails.

Claire Wiggins, BS, is a medical student; Talia Noorily, BA, is a medical student; and Christopher Rizk, MD, is a dermatology fellow, Baylor College of Medicine, Houston, Texas.

References

1. Richardson LJ, Kratochvil FJ, Zieper MB. Unusual palatal presentation of oral psoriasis. J Can Dent Assoc. 2000;66:80-82.
2. Saunier  J, Debarbieux  S, Jullien  D, Garnier  L, Dalle  S, Thomas  L.  Acrodermatitis continua of Hallopeau treated successfully with ustekinumab and acitretin after failure of tumour necrosis factor blockade and anakinra.  Dermatology. 2015;230(2):97-100.
3. Mobini N, Toussaint S, Kamino H. Noninfectious erythematous, papular, and squamous diseases. In: Elder DE, Elenitsas R, Johnson B, Murphy G, eds. Lever’s Histopathology of the Skin. 9th edition. Philadelphia: Lippincott,Williams & Wilkins; 2005:174-210.
4. Yerushalmi J, Grunwald MH, Hallel-Halevy D, et al. Chronic pustular eruption of the thumbs. Diagnosis: acrodermatitis continua of Hallopeau (ACH). Arch Dermatol. 2000;136:925-930.
5. Benjegerdes KE, Hyde K, Kivelevitch D, Mansouri B. Pustular psoriasis: pathophysiology and current treatment perspectives. Psoriasis (Auckland, NZ). 2016;6:131-144.
6. Tosti A, Piraccini B. Nail disorders. In: Bolognia J, Schaffer JV, Cerroni L. Dermatology. 4th edition. Philadelphia: Elsevier Saunders; 2018:1203-1219.
7. Barron JA. Acrodermatitis of Hallopeau and erosive oral mucositis successfully treated with secukinumab. JAAD Case Rep. 2017;3:215-218.
8. Sehgal VN, Verma  P, Sharma S, et al.  Acrodermatitis continua of Hallopeau: evolution of treatment options.  Int J Dermatol. 2011;50(10):1195-1211.
9. Piraccini BM, Fanti PA, Morelli R, Tosti A. Hallopeau’s acrodermatitis continua of the nail apparatus: a clinical and pathological study of 20 patients. Acta Derm Venereol. 1994;74:65-67.
10. Twelves S, Mostafa A, Dand N, et al. Clinical and genetic differences between pustular psoriasis subtypes (published July 21, 2018). J Allergy Clin Immunol. doi: 10.1016/j.jaci.2018.06.038