Pemphigus Herpetiformis Presenting With Mucosal Involvement: A Rare Clinical Presentation.

Pemphigus herpetiformis (PH) is a rare autoimmune blistering disorder, considered a variant of pemphigus, characterized by clinical features resembling dermatitis herpetiformis and immunopathologic findings consistent with pemphigus. Patients typically present with pruritic, urticarial, papular, or vesiculobullous eruptions, while mucosal involvement is uncommon. Due to its overlapping clinical and histopathologic features with those of other blistering diseases, the diagnosis can be challenging. We report a case of a 49-year-old female who presented with itchy and painful, well-defined erythematous crusted plaques involving the face and upper chest, accompanied by mucosal involvement. Histopathological examination revealed an intraepidermal suprabasal cleft, superficial perivascular inflammatory infiltrate composed of lymphocytes and eosinophils, and intraepidermal vesicles containing neutrophils. Direct immunofluorescence demonstrated intercellular IgG and C3 deposition in a characteristic chicken-wire pattern, consistent with PH. Serologic testing showed strong positivity for desmoglein 1 and desmoglein 3 antibodies. The patient was treated with systemic corticosteroids and mycophenolate mofetil, resulting in an excellent clinical response. This case highlights the diagnostic challenges and clinical heterogeneity of PH, particularly mucosal involvement, an atypical immunologic profile, and therapeutic response. Increased awareness of this rare entity is essential to ensure accurate diagnosis and appropriate management.