A diagnostically challenging case of pemphigus foliaceus without histologic evidence of acantholysis

A 77-year-old woman presented with pruritic, scaly, erythematous papules and plaques on the face, which subsequently spread to the trunk. Over nearly 2 years, 5 skin biopsies were performed, consistently suggesting a subacute to chronic eczematous process without acantholysis or intraepidermal bullae. After 2 years of unsuccessful treatment, enzyme-linked immunosorbent assay demonstrated elevated anti desmoglein-1 IgG and normal anti desmoglein-3 IgG. Direct immunofluorescence of a skin biopsy revealed IgG and C3 deposition in the intercellular spaces. A diagnosis of pemphigus foliaceus was established, and the patient was treated with rituximab, resulting in significant clinical improvement. This case illustrates a diagnostically challenging presentation of pemphigus foliaceus in which multiple biopsies failed to demonstrate acantholysis or intraepidermal bullae (classic histologic features) highlighting the importance of immunologic testing in the evaluation of suspected autoimmune blistering disorders.