Our patient is a 63-year-old white woman who presented to the emergency department with a 2-week history of a diffuse blistering eruption involving nearly the entire body surface area as well as the oral mucosa, by report beginning on the lower extremities and quickly progressing. The lesions were pruritic and, at times, painful. She denied taking any new medications in the month before onset.
The patient's vital signs in the emergency department included a blood pressure of 123/77 mmHg, a pulse rate of 97 bpm, a temperature of 98.2 F (36.8 C), a respiratory rate of 18 rpm, and an oxygen saturation of 99% on room air. She denied fever, chills, shortness of breath, and chest pain. She also denied any known COVID-19 exposure.
On the basis of the patient's history and physical examination, which one of the following is the most likely diagnosis?
- Epidermolysis bullosa acquisita
- Linear IgA bullous dermatosis
- Primary varicella-zoster infection
- Bullous impetigo
The answer is D: linear IgA bullous dermatosis.
The tense nature of the blisters, containing serous or hemorrhagic fluid, is indicative of a subepidermal blistering disease. Subepidermal blistering diseases can also involve the mucous membranes and classically present in individuals over the age of 60 years (Kridin, 2018; Montagnon, Tolkachov, et al., 2021). Clinical manifestations of each entity vary, and because of the polycyclic or “crown of jewels” pattern seen on clinical examination (Figure 1), linear IgA bullous dermatosis (LABD) was favored.
LABD is relatively rare; the true prevalence is unknown but estimated to be between 0.2 and 1.0 cases per million people per year (Montagnon, Tolkachov, et al., 2021). It typically presents in individuals over the age of 60 years; however, a childhood form can also be seen in children under 4 years old. Although not associated with high mortality rates, if left untreated, LABD may persist for several years and have a detrimental effect on a patient's quality of life. Scarring is not expected. Associations with drugs such as vancomycin, gastrointestinal disease, malignancy, and infection have been reported (Montagnon, Tolkachov, et al., 2021).
Clinically, LABD can be difficult to distinguish from other subepidermal blistering dermatoses. If present, the presence of the “crown of jewels” formation can help to raise clinical suspicion (Figure 1). However, a skin biopsy revealing a subepidermal blister and direct immunofluorescence (DIF) showing linear deposition of IgA at the basement membrane zone is needed to confirm the diagnosis (Montagnon, Tolkachov, et al., 2021). Dapsone is the therapy of choice in patients with LABD, and signs of clinical response can be expected within 1 week (Genovese et al., 2019; Montagnon, Lehman, et al., 2021).
Shave biopsies of the patient's right thigh were performed on an intact blister for hematoxylin and eosin evaluation and an area of perilesional skin for DIF. The histopathological evaluation revealed subepidermal vesiculobullous dermatitis with neutrophils and eosinophils. DIF revealed a linear deposition of IgA along the basement membrane zone, consonant with LABD (Montagnon, Tolkachov, et al., 2021). Staining for IgG, IgM, C3, and fibrinogen was negative.
Epidermolysis bullosa acquisita (EBA) is also a subepidermal blistering disease. In contrast, it involves autoantibodies against Type VII collagen resulting in IgG linear deposition at the dermal–epidermal junction. EBA can be difficult to distinguish from LABD on physical examination alone; however, EBA is usually limited to areas of trauma (extensor knees, elbows, hands, and feet) and often heals with milia given the depth of the split at the basement membrane zone. In addition, the “crown of jewels” appearance is not typically seen in EBA (Kridin et al., 2019).
Primary varicella zoster virus infection typically presents with vesicles and not bullae, with the vesicles being present in varying stages and characteristically on an erythematous macule, pathognomonically described as a dew drop on a rose petal (Kennedy & Gershon, 2018).
Bullous impetigo is more common in young children. Typical disease course involves formation of fragile, flaccid bullae that rupture and result in round erosions with or without honey-colored crusts. Bullous impetigo also does not present with oral erosions (Watkins, 2013).
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