Spongiform pemphigoid: A case series of an uncommon histopathologic pattern

Introduction Bullous pemphigoid is an autoimmune bullous disease characterized by subepidermal separation. We encountered cases of bullous pemphigoid confirmed by direct immunofluorescence study but demonstrating spongiotic dermatitis without subepidermal clefting. Many of them occurred in volar sites, mimicking dyshidrotic dermatitis. Methods We retrospectively collected patients who were pathologically and/or immunopathologically diagnosed with bullous pemphigoid from 2002 to 2017. Patients who presented with prominent spongiosis without subepidermal clefting were included and compared with patients who were diagnosed with dyshidrotic dermatitis. Results A total of nine cases of spongiform pemphigoid out of 385 bullous pemphigoid patients (2.3%) were identified and compared with 15 patients with dyshidrotic dermatitis. Average age of spongiform pemphigoid patients (76 years) was much older than that of the control group (34 years). Microvesicles in the mid‐ to lower epidermis (P