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Race for the Case answers

Answers to Summer 2020 Race for the Case

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Diagnose this case by Angelia Stepian, MD

A 20-year-old female with no significant past medical history presented to the hospital with a one-week history of a diffuse blistering rash. One week prior to onset, the patient reports she took a pain reliever for headache relief. She denied any fever, arthralgias,edema, eye pain, throat pain, urinary issues, or abdominal discomfort. During her hospital stay, she had no laboratory abnormalities and her vital signs were within normal limits. On physical exam, no lymphadenopathy, peripheral edema, or joint tenderness was noted. Over her back, shoulders, arms, legs, chest, and face there were several erythematous annular plaques with surrounding tense vesicles in a “crown of jewels” arrangement and bullae with associated erosions and crust. No involvement of the palms, soles, or mucous membranes were noted. Biopsy showed a subepidermal blister with neutrophils and a perivascular infiltrate. Direct immunofluorescence demonstrated IgA (immunoglobulin A) and C3 (complement component 3) in a linear pattern along the basement membrane zone.

  1. What is the diagnosis? Answer: Linear IgA Bullous Dermatosis (LABD)
  2. In drug-induced cases, what is the most common culprit? Answer: Vancomycin
  3. What is the treatment of choice and what laboratory study must be ordered prior to initiation? Answer: Dapsone, G6PD must be ordered prior to initiation
  4. What are the two antibody targets in this condition? Answer: LAD-1 (120 kDa) and LABD-97 (97 kDa). Both are cleaved portions of the antigen BP180/BPAG2 located in the lamina lucida.
  5. What is on the differential diagnosis? Answer: Dermatitis herpetiformis, bullous pemphigoid, epidermolysis bullous acquisita, bullous fixed drug reaction, and porphyria cutanea tarda.

List of abbreviations:

BP180: bullous pemphigoid 180
BPAG2: bullous pemphigoid antigen 2
C3: complement component 3
IgA: immunoglobulin A
kDa: kilodaltons
LABD: linear IgA bullous dermatosis
LAD-1: ladinin-1

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