Non-blistering psoriasiform pemphigus foliaceus mimicking psoriasis: a diagnostic challenge

Abstract

Abstract Purpose Pemphigus foliaceus (PF) typically presents with superficial blistering but may occasionally manifest in atypical non-blistering forms that mimic other inflammatory dermatoses. We report a diagnostically challenging case of PF presenting with widespread psoriasiform plaques without clinically evident blistering. Methods A 71-year-old woman with a background of eczema presented with widespread erythematous, scaly plaques clinically resembling psoriasis. Skin punch biopsy was performed with histopathological examination and direct immunofluorescence testing. Results Histopathology demonstrated psoriasiform epidermal hyperplasia with parakeratotic crusting and foci of possible superficial acantholysis. Direct immunofluorescence revealed intercellular IgG and C3 deposition; although the immunofluorescence pattern was considered more compatible with pemphigus vulgaris, the histological findings were suggestive of pemphigus foliaceus. The final diagnosis of PF was established through clinical-pathological correlation. Following treatment of secondary Staphylococcus aureus infection and initiation of systemic corticosteroids with azathioprine and adjunctive doxycycline, the patient achieved marked clinical improvement with resolution of plaques within six weeks. Conclusions This case highlights that PF may present without clinically apparent blistering and can closely mimic psoriasiform dermatoses. Histopathological examination with immunopathological correlation is essential for accurate diagnosis. Early recognition and prompt systemic immunosuppressive therapy can lead to excellent clinical outcomes.