Infant’s pustular eruption is not scabies

Figure

The case

An anxious mother brings her healthy 4-month-old daughter for evaluation of itchy pustules on both hands and feet. The eruption has persisted despite 2 courses of permethrin for scabies. The infant also was diagnosed with hand-foot-and-mouth syndrome and dyshidrotic eczema, but neither of these diseases fit clinically.

Acropustulosis of infancy

Discussion

Acropustulosis of infancy (AI) is characterized as a recurrent, pruritic pustular eruption that commonly involves hands and feet.^1-3 Lesions first present at 2 to 3 months of age. Pustules generally remain for 1 to 3 weeks with frequent recurrences every few weeks to months. The chronic, repetitive nature gradually declines in severity before resolution around age 3 years.³

The true etiology of acropustulosis of infancy is unknown.⁴ It is often misdiagnosed as recurrent scabies leading to multiple doctor visits and unnecessary treatment with permethrin cream.  The misdiagnosis causes families to be frustrated and discouraged. Also, AI has been identified after scabies infection particularly in the developing world.^4-6 However, the connection between AI and scabies remains unclear. Acropustulosis is frequently reported in internationally adopted children, possibly because of previous crowded and unsanitary living conditions that may predispose to scabies infestation.⁴

Clinical findings

Well-circumscribed, round, vesiculopustular lesions are present in an acral distribution, most commonly on the palms and soles.^1-3 Classic AI lesions can be highly pruritic. Pustules are present for 1 to 3 weeks with frequent recurrence. Healed eruptions often leave behind postinflammatory hyperpigmentation with a collaret of scale. Importantly, no scabies mites or burrows are seen.

Differential diagnosis

Differential diagnosis for acropustulosis of infancy remains broad, most commonly confused with scabies, dyshidrotic eczema, transient neonatal pustular melanosis (TNPN), impetigo, and hand-foot-and-mouth disease (HFMD).

Scabies 

Scabies can present at any age. In infants, scabies often will have highly inflammatory, serpiginous or J-shaped burrows with papules and nodules in comparison to the circular vesicles and pustules of acropustulosis of infancy.⁷ Family members often have a history of similar pruritic lesions. Scabies is not recurrent if the patient and family are properly treated with permethrin cream.

Dishidrotic eczema

Dishidrotic eczema (pompholyx) is a recurrent bullous or vesicular eruption that usually symmetrically affects the palmoplantar skin and is associated with intense pruritus.⁸ Unlike AI, dyshidrotic eczema can present at any age and is more likely to have tense bulla formation.

TNPN

Transient neonatal pustular melanosis presents at birth with vesicopustular lesions that easily rupture 24 to 48 hours after onset, leaving behind hyperpigmented macules.⁹ It commonly affects the trunk and extremities unlike the acral distribution of AI, although it is not recurrent and is often asymptomatic.

Impetigo neonatorum 

Impetigo neonatorum is classically seen in the newborn period with the combination of superficial pustules, vesicles, and bullous lesions.¹⁰ Unlike AI, impetigo lesions generally occur on the face and flexural surfaces with culture positive for Staphylococcus aureus.

HFMD 

Hand-foot-and-mouth disease is most commonly caused by coxsackievirus with distinctive, symmetric, 2-mm-to-4-mm, round clustered papulovesicles that often become crusted on an erythematous base.¹¹ Lesions typically occur on the distal extremities including the palms, soles, buttocks, and around the mouth. Lesions may be itchy but are often asymptomatic, and tend to occur most densely in areas where the skin is injured, such as in patches of eczema, burns, or other minor trauma^. Unlike AI, HFMD is not recurrent.

Management

First-line therapy remains moderate to high-potency topical corticosteroids.⁶ Systemic antihistamines also have been used for pruritus relief.

Patient outcome

The patient was started on high-dose topical steroid with clobetasol to both feet sparingly for 1 to 2 weeks, resulting in a dramatic decrease in scratching. Emollients were continued 2 to 3 times a day and the topical steroid was used intermittently up to twice daily only as needed.

References:

1. Kahn G, Rywlin AM. Acropustulosis of infancy. Arch Dermatol. 1979;115(7):831-833.

2. Jarratt M, Ramsdell W. Infantile acropustulosis. Arch Dermatol. 1979;115(7):834-836.

3. Dromy R, Raz A, Metzker A. Infantile acropustulosis. Pediatr Dermatol. 1991;8(4):284-287.

4. Good LM, Good TJ, High WA. Infantile acropustulosis in internationally adopted children. J Am Acad Dermatol. 2011;65(4):763-771.

5. Elpern DJ. Infantile acropustulosis and antecedent scabies. J Am Acad Dermatol. 1984;11(5 pt 1):895-896.

6. Mancini AJ, Frieden IJ, Paller AS. Infantile acropustulosis revisited: history of scabies and response to topical corticosteroids. Pediatr Dermatol. 1998;15(5):337-341.

7. Hill TA, Cohen B. Scabies in babies. Pediatr Dermatol. 2017;34(6):690-694.

8. Wollina U. Pompholyx: a review of clinical features, differential diagnosis, and management. Am J Clin Dermatol. 2010;11(5):305-314.

9. Agusti-Mejias A, Messeguer F, Febrer I, Alegre V. Transient neonatal pustular melanosis [article in English, Spanish]. Actas Dermosifiliogr. 2013;104(1):84-85.

10. George A, Singh JS, Kaur G, Thomas E. Extensive pustules in a neonate. Diagnosis: impetigo neonatorum. Pediatr Dermatol. 2014;31(5):609-610.

11. Ventarola D, Bordone L, Silverberg N. Update on hand-foot-and-mouth disease. Clin Dermatol. 2015;33(3):340-346.