Atypical Case of Pemphigus Erythematosus in a Previously Healthy Young Woman: Diagnostic Delay and Response to Rituximab.

Pemphigus erythematosus, also known as Senear-Usher syndrome, is a rare localized variant of pemphigus foliaceus characterized by superficial blistering in seborrheic regions and immunopathologic overlap with systemic lupus erythematosus. This report describes an otherwise healthy 33-year-old woman with no significant past medical history presenting with widespread erosive plaques and crusted lesions predominantly in seborrheic areas, positive desmoglein-1 antibodies, positive antinuclear antibody (ANA), and histopathology consistent with intraepidermal acantholysis. Our patient demonstrated clinical improvement after systemic corticosteroids and rituximab, with no new bullae formation. This case highlights the diagnostic challenges associated with pemphigus erythematosus, the importance of clinicopathologic correlation, and the potential role of biologic therapy in the treatment of this condition.