Lesions expand at blistering speed in baby boy

The Case

Another bouncing, 8-month-old baby boy comes to your office with a blistering eruption and a very worried mother. Although the blisters have been spreading for a week, he continues to feed, sleep, and behave normally, except for scratching his neck. He was started on oral antibiotics and antiviral therapy in the emergency department (ED) 3 days ago without improvement. Bacterial and viral cultures from the ED visit are negative. What are these blisters?

Diagnosis: Linear IgA bullous dermatosis (chronic bullous dermatosis of childhood)

In addition to cutaneous lesions, oral and ocular lesions may appear. Oral lesions, seen in 50% of cases, can present as vesicles, ulcerations, erosions, gingivitis, or cheilitis.^1,2 Ocular signs such as subconjunctival fibrosis and symblepharon formation can be present and asymptomatic.³

PATHOPHYSIOLOGY

Linear IgA bullous dermatosis (LABD) is an autoimmune, blistering disease that typically develops before the fifth year of life.¹ The etiology of LABD is uncertain, although some investigators postulate that it is caused by a postinfectious immunologic reaction.^4,5 Direct immunofluorescence on skin histopathology shows a linear pattern of IgA antibodies specific to the basement membrane zone (BMZ).⁶ Indirect immunofluorescence can show circulating BMZ-specific IgA antibodies. In 1 study of adult patients, all LABD patients had positive serum IgA antibodies to either the BP180 or BP230 autoantigen sites.⁷ However, in a study of Tunisian children with LABD, indirect immunofluorescence was negative in 67% of cases.⁸

DIFFERENTIAL DIAGNOSIS

In infants with an acute widespread blistering eruption, the differential diagnosis would include eczema herpeticum, varicella, impetigo, and rarely other autoimmune blistering disorders. An accurate history and physical exam are essential to differentiating among these disease processes.

Unlike eczema herpeticum, patients with LABD typically are afebrile, have no lymphadenopathy, and are eating and drinking appropriately. Moreover, herpetic lesions usually are uniform in size and morphology and clustered. In varicella, the vesicles are widely scattered with involvement of the skin and mucous membranes. Showers of new lesions appear between days 2 and 4, which result in lesions in various stages of evolution over the subsequent 7 to 10 days, but the central crusting may mimic the string-of-pearls characteristic of LABD.

The vesicles and bullae of impetigo are flaccid, variable in size and filled with pus. Other immunobullous disorders, such as epidermolysis bullosa acquisita, bullous pemphigoid, and dermatitis herpetiformis, may trigger similar eruptions and can be distinguished only by immunofluorescence studies.

TREATMENT

Dapsone currently is the first-line treatment and has been shown to be highly effective. However, dapsone is contraindicated for patients with a history of hypersensitivity reactions to it and should be used with caution in patients with hemolytic anemia or glucose-6-phosphate dehydrogenase deficiency. Other medications such as colchicine, sulfapyridine, trimethoprim, oxacillin, dicloxacillin, and flucloxacillin also have shown efficacy.^9-14 The response to therapy often is so rapid (1-3 days) that it can be used as an informal confirmation of the diagnosis. Oral or topical antibiotics may be necessary to treat secondary infection. Providers also should consider referring patients for an ophthalmologic appointment, as ocular findings may be present even in asymptomatic patients.

Children with LABD typically have a favorable prognosis, because most patients have an early response to medications. The autoimmune-driven disorder usually resolves in two-thirds of patients within 2 years of onset, although continuation into adulthood has been reported.^15,16 There also are reported cases of resolution followed by recurrence throughout puberty.¹⁷ Although cutaneous scarring usually does not occur, oral mucous membrane and ocular scarring can cause significant morbidity.