Are You Confident of the Diagnosis?
What to be alert for in the history
Infantile acropustulosis (IA) occurs in infants and young children, with onset typically occurring between 2 and 10 months of age, characterized by periods of activity and quiescence. Each eruption lasts approximately 7 to 14 days. Recurrence every few weeks is typical. It is typical for eruptions to shorten in duration and for periods of quiescense to increase with passage of time until spontaneous resolution occurs between age 2 and 3.
Characteristic findings on physical examination
Physical examination reveals crops of intensely pruritic vesicopustules and papules over the palms and soles, often with concentration of lesions at the junction of the plantar or palmar and dorsal foot or hand (Figure 1). Vesicles transition to pustules over 24 hours. Lesions can be seen on the dorsal surfaces of hands and feet, and to a lesser extent on face and scalp. Paroxysms of pruritus can lead to restlessness and sleeplessness among affected children.
Smears of intact pustules show a predominance of neutrophils; eosinophils may also be present. It has been suggested that younger infants may show a predominance of eosinophils that transition to a neutrophil predominant infiltrate with increasing age.
Expected results of diagnostic studies
Biopsy is rarely performed, but shows neutrophil predominant subcorneal pustules with an admixture of eosinophils. Necrolysis of keratinocytes can be seen.
The differential diagnosis includes scabies, which is the most difficult to differentiate from IA — in large part because IA can occur as a sequelae after scabies infection in many patients. Dyshidrotic eczema, pustular psoriasis, impetigo, transient neonatal pustular melanosis (TNPM) and erythema toxicum neonatorum (ETN) are also important to exclude. Confirmation of the diagnosis is made by excluding active scabies infection, with the characteristic eruption in an infant of the right age.
Clinical features that help to differentiate IA from scabies are that IA favors acral sites almost exclusively whereas infants with scabies typically have widespread involvement of burrows and papules on the trunk (including axillae and genitalia) and scalp, and other family members generally have similar findings. Positive scabies preparation is diagnostic, but negative scrapings are common even when performed by experienced practitioners in the presence of active scabies.
Dyshidrotic eczema is rare in infants and has differing histologic features of spongiosis and intraepidermal vesicles with lack of subcorneal pustules (typical of IA.)
Pustular psoriasis generally affects adolescents and adults, follows a chronic course, and has a background of pink plaques with overlying scale in addition to the pustules present. There is histologic overlap, but IA and pustular psoriasis are clinically distinct.
Impetigo may be differentiated from IA with positive bacterial culture and resolution after institution of appropriate oral antibiotics. Serous crust around excoriated lesions can also be a helpful distinguishing feature.
TNPM is typically present at birth and presents with vesiculopustules on the face, neck and trunk, which rupture leaving a collarette of fine scale that later resolves with post-inflammatory hyperpigmentation by 3 months of age. The age of onset and distribution are distinguishing features from IA. Severe pruritus is not expected in TNPM.
ETN has onset of small vesiculopapules and a “flea-bitten” appearance typically within the first 2 days of life with resolution by 2 weeks of age. The age of onset and the fact that acral surfaces are typically spared differentiates this condition from IA.
Who is at Risk for Developing this Disease?
IA is reported to be more common in African-Americans and non-Caucasian infants and male patients with typical age of onset before 10 months of age. There are reports of increased incidence in internationally adopted children immigrating to the United States. Preceding scabetic infestation is common, but not necessary or sufficient to make the diagnosis. It is typically more severe in warm weather and summer. Up to half of patients have a history of atopic dermatitis.
What is the Cause of the Disease?
The etiology of IA is unknown. History of preceding scabies infestation is common but not present in all cases. It has been suggested that IA is a recurrent cutaneous hypersensitivity reaction to residual antigen from prior scabies infestation. Such an antigen has not been identified to date. There is likely a de novo form of IA that occurs without a history of infestation and one that occurs after scabies has resolved. Clinically, they appear identical.
Systemic Implications and Complications
IA does not have associated systemic disease or complications, but peripheral eosinophilia may be noted and can occasionally be striking. Pruritus associated with the disorder is the most important symptom of IA. Secondary bacterial infection can occur within excoriated lesions and should be treated with topical and/or oral antibiotics as warranted by severity and bacterial culture and sensitivities.
– Medium- to high-potency topical steroids (class I – III) with or without occlusion are first-line therapy.
– Sedating antihistamines such as hydroxyzine (2mg/kg/day orally divided every 6 hours as necessary) or diphenhydramine (1 to 2mg/kg orally every 6 hours as necessary)
– Initial reports suggested dapsone at a dose of 2mg/kg/day as a treatment option. This drug should be reserved for severe, refractory cases and the potential hematologic and neurologic sequelae of this medication must be weighed heavily before prescribing this medication for a self-limited, benign condition in infants.
Optimal Therapeutic Approach for this Disease
Therapy should begin with medium- to high-potency topical corticosteroids in ointment formulation (eg, fluocinonide 0.05% ointment) applied twice daily under occlusion in conjuction with hydroxyzine at therapeutic dosing (see above), treating to symptom relief and/or somnolence. Diphenhydramine is another option. Symptom relief should be expected with topical steroids and oral antihistamines within the first few days of use. Despite conflicting reports in the medical literature (primarily in older reports), response to high-potency topical steroids is generally good.
There is one case report of the use of the vitamin D analogue maxacalcitol (not available in the United states) for treatment of IA. Hypercalcemia is a potential side effect, and caution should therefore be exercised in this age group.
The use of dapsone has fallen out of favor, given the response to topical corticosteroids in most cases and the potential for hematologic (aplastic anemia), hepatic (hepatitis), and neurologic (peripheral neuropathy) sequelae. G6PD testing should be performed in all patients prior to initiation of dapsone.
Patients should be seen in follow-up every few months after disease is stable on topical corticosteroid and oral antihistamine therapy. Parents should be instructed to apply steroids and use antihistamines at the first sign, and for the duration, of outbreaks, which typically last up to 2 weeks, taking breaks from therapy during remissions. If mid-potency topical steroids are ineffective after 1 week, higher potency steroids should be prescribed, using class I steroids if clinically warranted.
If dapsone were to be employed, there should be extensive discussion with the family about the risks (see above) and benefits of therapy. G6PD, CBC, and LFTs should be checked at baseline, then a CBC should be drawn weekly for 4 weeks, then monthly for 6 months, and every 6 months thereafter. LFTs should be rechecked every 3 months.
Unusual Clinical Scenarios to Consider in Patient Management
If other family members present with symptoms suggestive of scabies, the diagnosis should be re-evaluated and a new skin scraping performed. There is one case report of eosinophilic pustular folliculitis of infancy and IA affecting the same patient, with the suggestion that the pathophysiology of both conditions is similar and histologic differences are related to the site of involvement (scalp versus acral skin.)
What is the Evidence?
Good, LM, Good, TJ, High, WA. “Infantile acropustulosis in internationally adopted children”. J Am Acad Dermatol. 2011 May 30. (This article discusses 38 cases of IA in children adopted from Vietnam, China, Ethiopia, Russia and Guatemala. It is one of only two original articles published on IA in the last decade and captured cases in a novel way (a survey posted on adoption blogs and Web sites). It has a good discussion section and good clinical and histologic photos.)
Kimura, M, Higuchi, T, Yoshida, M. “Infantile acropustulosis treated successfully with topical maxacalcitol”. Acta Derm Venereol. vol. 91. 2011. pp. 363-4. (The other original article published within the past 10 years, and the only publication discussing treatment with a vitamin D analogue.)
Braun-Falco, M, Stachowitz, S, Schnopp, C, Ring, J, Abeck, D. “Infantile acropustulosis successfully controlled with topical corticosteroids under damp tubular retention bandages”. Acta Derm Venereol. vol. 81. 2001. pp. 140-1. (A case report with practical discussion of use of occlusion with topical steroids for therapy of IA.)
Mancini, AJ, Frieden, IJ, Paller, AS. “Infantile acropustulosis revisited: history of scabies and response to topical steroids”. Pediatr Dermatol. vol. 15. 1998. pp. 337-41. (An excellent, must-see review of the literature and discussion of 21 new cases of IA, with a good discussion of potential pathophysiology of the condition.)
Vicente, J, Espana, A, Idoate, M, Iglesias, ME, Quintanilla, E. “Are eosinophilic pustular folliculitis of infancy and infantile acropustulosis the same entity”. Br J Dermatol. vol. 135. 1996. pp. 807-9. (This article draws an interesting potential association between two entities thought previously to be unassociated.)
Lucky, AW, McGuire, JS. “Infantile acropustulosis with eosinophilic pustules”. J Pediatr. vol. 100. 1982. pp. 428-9. (This is the first publication to reveal the possible presence of an eosinophilic infiltrate in the pustules of IA, in addition to neutrophils.)
Jarrett, M, Ramsdell, W. “Infantile acropustolosis”. Arch Dermatol. vol. 115. 1979. pp. 834-6. (This is one of the two original articles describing IA as a new entity.)
Kahn, G, Rywlin, AM. “Acropustulosis of infancy”. Arch Dermatol. vol. 115. 1979. pp. 831-3. (This article is one of the two original articles describing IA as a new entity. Interestingly, Kahn’s cases both had onset at birth, which was atypical of future cases of IA described in the literature.)
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