A skin biopsy specimen of lesional skin showed a subepidermal bulla containing a dense papillary dermal neutrophilic infiltrate. An alcian blue stain revealed minimal interstitial dermal mucin deposition. Direct immunofluorescence (DIF) of perilesional skin showed a bright, dense, granular/fibrillar and focally linear pattern at the dermoepidermal junction and around adnexal structures with IgG (1-2+), IgM (1-2+), and IgA (trace) as well as a homogeneous and focally granular pattern with C3. Salt-split skin examination revealed that the immunoreactants were present at the floor of the blister and around hair follicles. Our patient had a dramatic improvement with dapsone therapy (50 mg/d).
Crusted Erythematous Postauricular Plaques. Arch Dermatol. 2001;137(8):1095-1100. doi: