Beyond Herpes: A Case of Oral-Dominant Pemphigus Vulgaris Initially Misdiagnosed as Herpetic Stomatitis

Pemphigus vulgaris (PV) is a rare, potentially life-threatening autoimmune vesiculobullous disorder that frequently presents first in the oral cavity, often before any skin involvement appears. Because early oral lesions are non-specific, PV is commonly misdiagnosed as herpetic stomatitis, aphthous ulceration, or other vesiculobullous conditions, delaying appropriate immunosuppressive treatment. We report the case of a 26-year-old female who presented with recurrent, painful oral blisters previously diagnosed and treated as herpetic stomatitis by other clinicians, without improvement. Clinical examination revealed flaccid bullae that ruptured to leave raw, eroded surfaces, with a positive perilesional Nikolsky sign confined to the oral mucosa; systemic features of herpetic infection (fever, lymphadenopathy) were absent. Incisional biopsy confirmed suprabasal acantholysis, consistent with pemphigus vulgaris. The patient was managed with systemic corticosteroids (methylprednisolone), intralesional triamcinolone acetonide, and supportive therapy, with significant clinical improvement and reduction in lesion burden. This case highlights the importance of considering pemphigus vulgaris in the differential diagnosis of persistent oral bullous lesions that do not respond to antiviral therapy and underscores the diagnostic value of the Nikolsky sign and biopsy in distinguishing PV from herpetic stomatitis. Keywords: Pemphigus vulgaris; Oral bullae; Nikolsky sign; Suprabasal acantholysis; Herpetic stomatitis; Misdiagnosis