A 26-month-old boy with a diffuse bullous eruption

A 26-month-old boy presented for evaluation of acute onset of vesicles that began on his trunk and later spread to his arms, legs and groin. He was initially diagnosed with impetigo and given oral and topical antibiotics without improvement. He was later given multiple 5-day courses of prednisone, which initially improved the rash for a few days, but the eruption flared each time he completed treatment.

The lesions were mildly pruritic and appeared to be tender and bothersome when healing with no other associated symptoms. The patient had not experienced blistering lesions before this eruption and was otherwise healthy. His parents denied any sick contacts or exposure to poison ivy, and his family history was unremarkable.

On exam, the patient had grouped, erythematous, annular, tense vesicles and bullae on his trunk, arms, legs, scrotum and inguinal folds (Figure). His eyes and oral mucosa were clear. No other significant findings were noted on physical exam.

Source: Boulos S.

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Case Discussion

Also known as chronic bullous disease of childhood or linear IgA disease, linear IgA bullous dermatosis (C), is the most commonly acquired immunobullous disorder in children with a typical onset between ages 6 months and 5 years. LABD can present after an infection or exposure to antibiotics like vancomycin, amoxicillin-clavulanate and trimethoprim-sulfamethoxazole.

This condition is characterized by the acute onset of clear and hemorrhagic vesicles and bullae with new lesions forming at the border of older ones, forming a ring or “string of pearls.” Lesions can be variably pruritic and primarily affect the lower trunk, neck, and perineal areas. Mucosal involvement is more common in the pediatric population. The rash can be associated with fever, malaise, and other prodromal symptoms.

Histologically, LABD is indistinguishable from bullous pemphigoid with subepidermal bullae and a polymorphous inflammatory infiltrate. Direct immunofluorescence of perilesional skin showed linear IgA deposits along the dermal-epidermal junction; circulating IgA and sometimes IgG autoantibodies to specific basement membrane components are detected in up to 80% of patients.

LABD responds well to treatment. While dapsone (Aczone, Allergan) is the drug of choice, alternative options include potent topical steroids in mild cases, and sulfapyridine, systemic corticosteroids, mycophenolate mofetil, erythromycin, dicloxacillin, or sulfonamides in more severe cases. In pediatric patients, spontaneous remission occurs anywhere from several months up to 5 years.

The differential includes other bullous disorders including varicella, bullous pemphigoid, epidermolysis bullosa acquisita and poison ivy.

Primary varicella (chickenpox) is typically a benign, self-limited vesicular eruption in children caused by the varicella zoster virus. The infection is transmitted via airborne respiratory droplets and may be associated with a prodrome of fever, chills, irritability, headache and myalgias. Varicella presents with pruritic, erythematous macules that become papules and then superficial vesicles with a rim of erythema, forming “dewdrops on a rose petal.” The eruption usually starts on the trunk, face, or scalp and spreads to the extremities. The vesicles evolve into pustules and the lesions form crusts that heal within 10 days.

Bullous pemphigoid presents clinically and histologically like LABD, with tense bullae due to subepidermal blisters, but does not often exhibit a “string of pearls” pattern. However, the direct immunofluorescence pattern of perilesional skin in bullous pemphigoid shows linear deposition of IgG and C3 along the dermal epidermal junction. Patients usually have circulating IgG autoantibodies to specific basement membrane components, BP180 and BP230. Treatment options include high potency topical corticosteroids, prednisone, minocycline, dapsone, and other immunosuppressants such as mycophenolate mofetil, azathioprine, cyclosporine, and methotrexate.

Epidermolysis bullosa acquisita is a rare subepidermal blistering disorder caused by autoantibodies to type VII collagen. Epidermolysis bullosa acquisita presents either as the noninflammatory acral mechanobullous subtype with scarring and milia development, or the diffuse inflammatory subtype that presents similarly to bullous pemphigoid with comparable treatment options.

Poison ivy is a type IV delayed hypersensitivity reaction caused by Rhus and Toxicodendron plant species. The eruption is characterized by extremely pruritic, erythematous papules, vesicles, and bullae usually on exposed areas and in a linear array. Urushiol, the oily resin in the sap of the plant, can become oxidized and leave black dots on the skin. Depending on the severity, the dermatitis is treated with potent topical steroids or a course of prednisone.

While blistering skin diseases have many etiologies, there are certain patterns and presentations that can help direct further workup, diagnosis and treatment options. Recognizing linear IgA bullous dermatosis in children is particularly important because it will expedite workup and treatment.

• References:
• Eichenfield LF, et al. Neonatal and Infant Dermatology. 3rd ed. Elsevier; London; 2015.
• Marathe K, et al. Clin Dermatol. 2015;doi:10.1016/j.clindermatol.2015.09.007.
• Mutasim DF, et al. J Am Acad Dermatol. 2005;doi:10.1016/j.jaad.2004.11.064.
• Paller AS, et al. Hurwitz Clinical Pediatric Dermatology: A Textbook of Skin Disorders of Childhood and Adolescence. 5th ed. Elsevier; London; 2016.

• For more information:
• Scarlett Boulos, MD, is a pediatric dermatology fellow at The Children’s Hospital of Philadelphia. She can be reached at bouloss@email.chop.edu.
• Marissa J. Perman, MD, is an attending physician at The Children’s Hospital of Philadelphia.

Disclosures: Boulos and Perman report no relevant financial disclosures.