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Download the article PDF: Clinical Image Challenges
Differential Diagnosis
- Erythrodermic psoriasis
- Pemphigus foliaceus
- Pemphigus vulgaris
- Subcorneal pustular dermatosis
- Dermatitis herpetiformis
- Bullous impetigo
Diagnosis
- The correct diagnosis is pemphigus foliaceus, a rare autoimmune disease that causes blisters on the skin (but not the mucous membranes, as in pemphigus vulgaris). A skin biopsy with H&E staining shows damage (acantholysis) in the upper layer of the skin. Direct immunofluorescence (DIF) shows IgG and C3 deposits spread evenly throughout the skin layer. Blood tests using ELISA detect antibodies against a protein called desmoglein 1 (Dsg1). The main harmful antibodies are mostly of the IgG4 type, and they target Dsg1, though other antibody types and targets may also be involved.
What To Look For
- Superficial blisters, crusted erosions, and scaling in a seborrheic distribution (ie, scalp, face, and upper trunk). Lesions usually start on the trunk and rarely involves the mucosa.
- Nikolsky sign will be present in active disease, elicited by lateral pressure with a thumb or finger to the perilesional, affected, or normal-appearing skin, resulting in visible separation of the upper epidermal layers from the lower layers.
- In individuals with darker skin tones, healing may be accompanied by hypo- or hyperpigmentation
Pearls For Urgent Care Providers
- Corticosteroids are the first-line treatment for both adult and pediatric cases. Prednisone or prednisolone (1.0-1.5 mg/kg/day in a single dose or divided into 2 doses) may be used for acute control, especially with more severe cases.
- Sun avoidance and sun-protection measures (eg, using sunscreens, wearing barrier clothing) should be instituted.
- If biopsy and lab testing is not available in Urgent Care, referral to dermatology is appropriate for diagnostics and ongoing management.
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A 42-year-old Female with a Widespread Scaly Rash
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