Infantile Acropustulosis - Symptoms, Diagnosis, and Treatment

Introduction

Acropustulosis is an itchy and uncomfortable skin condition that affects babies. It is also called infantile acropustulosis (IA). It mainly occurs on the palms and the soles of the affected infants. It clears within a few weeks after onset. Hence, the condition is self-limiting.

What Is the Pathophysiology of Infantile Acropustulosis?

The pathophysiology (disease process) of IA is unknown. IA is usually preceded by scabies infection. A mite infection causes scabies. IA is common in adopted children from foreign countries. It is because they have a higher incidence of scabies infestation. Atopic dermatitis (eczema) is also associated with IA. Eczema leads to dry, itchy, and inflamed skin.

The deficiency of interleukin 1 receptor antagonist (DIRA) is a recently recognized mechanism of IA. Interleukin 1 receptor antagonist (IRA) is secreted by monocytes and macrophages (immune cells). IRA inhibits interleukin-1 (IL-1). IL-1 invokes an inflammatory response. Hence, the deficiency of the IRA leaves IL-1 unopposed. As a result, it leads to skin inflammation.

What Is the Etiology of Infantile Acropustulosis?

It is not known what causes IA. Scabies has been documented to be a preceding or concomitant infestation in some cases. Many children are misdiagnosed with scabies and also treated for the same. Various studies report that IA is a skin hypersensitivity reaction to antigens (allergies) associated with scabies. However, no other infectious agent is reported.

How Common Is Infantile Acropustulosis?

The frequency of IA is unknown. Reports suggest a male predominance. The lesions completely resolve in three years. Furthermore, IA has no ethnic predisposition.

What Is the Clinical Presentation of Infantile Acropustulosis?

A typical clinical presentation involves history and patient examination.

1. History: The classic history of IA is an infant aged two-twelve months developing recurrent crops of pruritic (itchy) erythematous (red) macules or papules. Macules are flat-topped lesions, whereas papules are raised. They further progress into vesicles (blisters) and pustules (pus-filled lesions). The lesions are sometimes present at birth. Infants present as irritated and uncomfortable.

2. Physical Examination: IA is distinguished by recurrent outbreaks of crops of small macules or papules. These eventually form distinct vesicles and pustules. Lesions occur on the palms, soles, and lateral finger surfaces. However, the feet, trunk, scalp, and face are less commonly involved. Temporary pigmentation is noted after lesion healing. These areas represent skin inflammation. It is called post-inflammatory hyperpigmentation that resolves after some time.

What Is the Differential Diagnosis of Infantile Acropustulosis?

It is important to differentiate IA from other skin lesions. For an infant presenting with IA, diseases are separated into various categories.

1. Hand, Foot, and Mouth Disease: IA is sometimes mistaken as hand, foot, and mouth disease (HFMD). It is because HFMD also causes blisters on the palms and soles. However, HFMD begins with a fever and sore throat. Further, there can be mouth sores and involvement of other body areas.

2. Scabies: Clinical features that help to differentiate IA from scabies are:

a) IA favors acral sites (extremities) whereas infants with scabies have widespread involvement of burrows and papules on the trunk and scalp. Further, axillae and genitalia are also involved in scabies.

b) Scabies is a highly contagious disease. Hence, other family members have a similar presentation.

c) Positive scabies preparation from skin scrapings is diagnostic. But, negative scrapings are common, even when done by experienced practitioners.

3. Chicken Pox: Widespread vesicles characterize chicken pox. Moreover, the cause is viral.

4. Candidiasis:Candidiasis is a fungal infection of the skin, genitourinary tract, and digestive system.

5. Herpes Simplex Viral (HSV) Infection: This is a manifestation of primary HSV-1 infection that occurs in children aged six months to five years. The mode of infection is infected saliva from an adult or another child.

6. Cutaneous Larva Migrans: It is a parasite-induced infection in which snake-like, reddish tunnels are found at the penetration site. Lesions are mainly distributed on the lower extremities.

7. Staphylococcal Scalded Skin Syndrome (SSSS): S. aureus causes this skin infection in children. It leads to acute skin exfoliation. Patients have a fever, skin redness, facial swelling, and dehydration. Furthermore, the skin appears sandpaper-like due to the rash.

How Is Infantile Acropustulosis Diagnosed?

Informing the pediatrician is very important if a lesion is noted on the infant’s skin. It is because IA can be mistaken for other conditions.

1. Laboratory Investigations: The diagnosis is mainly clinical. No laboratory studies are needed to diagnose IA. A complete blood cell count shows increased eosinophils (cells increased in allergy). Cultures and smears can rule out infectious etiology. They also show eosinophil and neutrophil predominance.

2. Histology: Biopsy is rarely performed. A pustule is examined for histology under a microscope. It contains neutrophils or eosinophils in the epidermis (uppermost skin layer). The continuation of neutrophils in the keratin layer is a characteristic of IA. Skin swelling (edema) and a mild perivascular (around the blood vessels) infiltrate of lymphocytes is appreciated. Direct immunofluorescence results are negative.

Diagnostic confirmation is done by excluding active scabies infection. The prognosis for IA is excellent. The bouts of pruritic vesicles and pustules decrease in severity with successive outbreaks. There is a definite resolution by age nine.

How Is Infantile Acropustulosis Managed?

Topical or systemic medications are used in IA treatment.

1. Topical Medications: Topical medications are applied directly to the lesions.

• Corticosteroids: A corticosteroid topical ointment containing Betamethasone valerate is used. It reduces skin inflammation and relieves itchiness. It has medium to high potency (strength).

• Antipruritics: Pramoxine relieves pain and itching. Topical Pramoxine blocks nerve conduction and impulses. Patients should use one percent lotion or cream.

2. Systemic Medications: Systemic medications are oral forms of treatment for IA.

• Antihistamines: Antihistamines such as Hydroxyzine and Diphenhydramine (0.9mg/lb/day) are given four times daily. They also help in sedation. Diphenhydramine is used for pruritus and allergies. On the other hand, Hydroxyzine has antipruritic, anxiolytic, and mild sedative effects.

• Antibiotics: A powerful antibiotic called Dapsone is sometimes used topically. It is mainly to treat severe acne. This drug should be reserved for severe and refractory cases. The hematologic and neurologic sequelae of this medication must be weighed before prescribing this medication. Hence, it is not widely used in IA.

Patients on topical corticosteroid and oral antihistamine therapy should be followed up every few months. Parents should be instructed to apply steroids and antihistamines at the first sign of the disease. If mid-potency topical steroids are ineffective for one week, higher-potency steroids should be prescribed.

Conclusion

IA is usually a temporary condition. However, it is important to recognize IA because of the frequent misdiagnosis and recurrence. Hence, appropriate medication and protecting the affected skin can reduce flare-ups. In most cases, flare-ups stop until a child is three years old.