A Case Report of Pemphigus Vulgaris Initially Misdiagnosed as Tinea Capitis: Infectious Consequences of Diagnostic Delay in a Patient Treated With Rituximab.

Pemphigus vulgaris is a rare and potentially life-threatening autoimmune blistering disorder affecting the skin and mucous membranes. Prompt diagnosis and appropriate treatment are crucial in preventing severe complications. We report the case of a 53-year-old woman with severe pemphigus vulgaris who was misdiagnosed as having tinea capitis for approximately four months. During this time, she received multiple courses of systemic antifungals and antibiotics without clinical improvement, resulting in the progressive dissemination of lesions, including mucosal and ocular involvement. The correct diagnosis was ultimately established through skin biopsy, and immunosuppressive therapy with prednisone and rituximab was initiated. During immunosuppression, the patient developed severe infections due to Pseudomonas aeruginosa, extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), necessitating the temporary suspension of rituximab and the introduction of intravenous immunoglobulin as a bridging strategy. The patient experienced favorable clinical evolution, with more than 80% reepithelialization and the resolution of infectious complications. This case underscores the importance of considering autoimmune diseases in treatment-refractory scalp dermatoses, avoiding prolonged empirical antimicrobial use, and employing a multidisciplinary approach in immunosuppressed patients at high risk of infection.