Pemphigus Foliaceus Mimicking Erythema Annulare Centrifugum: A Case Report.

Pemphigus foliaceus (PF) is an autoimmune blistering disease characterized by superficial, easily ruptured blisters that evolve into scaly erosions. Annular and polycyclic morphologies are uncommon in adults and can complicate diagnosis. Here, we describe the case of a 79-year-old woman with pruritic lesions on the trunk, proximal extremities, and face who had initially been treated for psoriasis. Skin examination revealed multiple erythematous annular and polycyclic plaques with central clearing and fine peripheral scaling, without vesicles or bullae. Skin biopsy findings indicated superficial intraepidermal clefting with acantholytic keratinocytes and only scant eosinophils and neutrophils. Direct immunofluorescence (DIF) demonstrated intercellular deposition of IgG and C3 throughout the epidermis. Serological testing confirmed elevated anti-desmoglein 1 and negative anti-desmoglein 3 antibody levels, establishing PF. Prednisolone with adjunctive intravenous immunoglobulin administration led to gradual improvement. Research concerning pediatric PF and erythema annulare-like acantholytic dermatosis supports the view that annular and polycyclic lesions are morphological variants within the PF spectrum. Timely biopsy, DIF, and serological autoantibody testing are key to establishing a diagnosis.