Linear Immunoglobulin A Bullous Dermatosis

A  6-year-old boy with no significant past medical history presented with crusted, erythematous erosions and vesicles involving the face, chest, back, legs, thighs, buttocks, and scalp (A). The eruption of blisters and vesicles had been present for 8 months. One month before presentation, he had developed a significant eruption involving the bilateral legs, buttocks, arms, and perioral area, but with no oral mucosal involvement. The patient was not on any medications and had no known drug allergies.

Direct immunofluorescence testing of a skin biopsy revealed linear deposition of immunoglobulin A (IgA) along the epithelial basement membrane zone, pointing to a diagnosis of linear IgA bullous dermatosis (LABD).

LABD is a chronic, autoimmune, bullous disease with 2 peaks of onset, one in prepubescence and another after age 60 years.¹ The disease results in characteristic deposits of IgA in a linear configuration along the basement membrane zone.² LABD blisters usually involve the face, trunk, groin, and legs.³ The blisters tend to form in a collection with associated erythema and pruritus,³ as with those of our patient (B). Approximately 50% of cases have associated oral mucosal involvement.³

Bullous impetigo is among the differential diagnoses for LABD.⁴ Misdiagnosis of LABD as bullous impetigo can result in treatment with oral antibiotics, which can mask the underlying disease process of LABD. Bullous impetigo is caused by Gram-positive, coagulase-positive Staphylococcus aureus, which release exotoxins that result in epidermal separation and the formation of bullae.⁴ Impetigo bullae usually are localized to the face and have a honey-crusted appearance on clinical examination; patients also may have fever.⁴ Additional differential diagnoses include other blistering disorders such bullous pemphigoid and pemphigus vulgaris.

The LABD diagnosis is made using direct immunofluorescence testing of a lesion biopsy, which will reveal the hallmark linear deposition of IgA at the basement membrane.

Many LABD triggers have been identified, including medications, trauma, burns, and systemic illnesses.⁵ Vancomycin is the medication most commonly associated with LABD²; amiodarone, captopril, and phenytoin also have been linked to the condition.⁵ While the disorder’s exact etiologic mechanism is unknown, it might result from an immunologic reaction, leading to characteristic changes at the basement membrane zone.⁵

Dapsone typically is first-line therapy for LABD, although it has been associated with serious adverse effects such as hemolytic anemia, methemoglobinemia, and bone marrow suppression.^1,6 Before initiating dapsone, a glucose-6-phosphate dehydrogenase level should be obtained to rule out G6PD deficiency.¹ Systemic corticosteroids also are a common treatment option, either adjunctively or for refractory cases.¹ Other therapies with reported success are sulfapyridine, cyclosporine, mycophenolate mofetil, and intravenous immunoglobulin.¹

It is important to counsel patients that LABD is self-limiting, with remission usually occurring in 3 to 6 years.¹

REFERENCES:

1. Ng SY, Venning VV. Management of linear IgA disease. Dermatol Clin. 2011;29(4):629-630.

2. Venning VA. Linear IgA disease: clinical presentation, diagnosis, and pathogenesis. Dermatol Clin. 2011;29(3):453-458.

3. Kneisel A, Hertl M. Autoimmune bullous skin diseases. Part 1: clinical manifestations. J Dtsch Dermatol Ges. 2011;9(10):844-856.

4. Welsh B. Blistering skin conditions. Aust Fam Physician. 2009;38(7):484-490.

5. Fortuna G, Marinkovich MP. Linear immunoglobulin A bullous dermatosis. Clin Dermatol. 2012;30(1):38-50.

6. Passos L, Rabelo RF, Matsuo C, Santos M, Talhari S, Talhari C. Linear IgA/IgG bullous dermatosis: successful treatment with dapsone and mycophenolate mofetil. An Bras Dermatol. 2011;86(4):747-750.