68 | FULMINANT SJS/TEN-LIKE PEMPHIGUS VULGARIS WITH HIGH ANTI-DSG1 TITERS AND CMV REACTIVATION: AN IMMUNOLOGICAL CHALLENGE

R. Daher², A. Verdelli¹, L. Sanna², V. Corti², A. Magnatta², S. Landini², M. Donati³, I. Bonanni¹, A. Corrà⁴, V. Ruffo Di Calabria⁵, E. Mariotti⁶, C. Della Bella⁷, L. Giovannoni⁸, M. D'Elios⁷, A. Moggi Pignone⁹, M. Caproni¹ | (1)Rare Dermatological Diseases Unit, Department of Health Sciences, University of Florence, Florence, Italy; (2)Section of Dermatology, Department of Health Sciences, University of Florence, Florence, Italy; (3)Dermatology Department, University of Modena and Reggio Emilia, Modena, Italy; (4)Dermatology Unit, Ospedale San Bortolo, Vicenza, Italy; (5)SSD Dermatologia, Cardinal Massaia Hospital, Asti, Italy; (6)Unit of Dermatology, Azienda USL Toscana Nord Ovest, Lucca, Italy; (7)Department of Molecular and Developmental Medicine, University of Siena, Italy; (8)UOC Ricerca e Sviluppo Clinical Practice, AOU Careggi, Florence, Italy; (9)Department of Experimental and Clinical Medicine, Division of Internal Medicine, University of Florence, Italy

Introduction. Pemphigus vulgaris (PV) is an autoimmune blistering disease driven by IgG autoantibodies against desmoglein (Dsg) 1 and 3. Rare fulminant variants may mimic Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). We report an exceptionally severe SJS/TEN-like PV in a previously healthy woman, focusing on its immunological basis and management.
Materials and Methods. Case report of a 55-year-old woman with an unremarkable history. The work-up included histology, direct (DIF) and indirect immunofluorescence (IIF), anti-Dsg1/Dsg3 ELISA, a viral panel and malignancy screening; disease activity was scored by PDAI.
Results. The patient developed rapidly progressive mucocutaneous erosions evolving into extensive epidermal detachment (PDAI activity 25), without drug trigger or fever. Histology showed suprabasal acantholysis; DIF revealed intercellular IgG1 and C3; IIF was positive (1:80). ELISA demonstrated markedly elevated anti-Dsg1 (107.5 IU/mL) with only modest anti-Dsg3 (9.6 IU/mL). Anti-envoplakin was negative and malignancy screening unremarkable, while rat-bladder IIF was unavailable. CMV reactivation (IgM positive) was detected and treated with ganciclovir. The Dsg1-dominant, discordant profile together with complement-fixing IgG1/C3 deposition supports antibody- and complement-mediated acantholysis as drivers of the SJS/TEN-like phenotype. Combined rituximab and intravenous immunoglobulin achieved rapid re-epithelialization. At 12-month follow-up the patient was in complete clinical and serological remission (PDAI 0; anti-Dsg negative), with no malignancy.
Conclusions. This case expands the clinical spectrum of PV, showing that high anti-Dsg1 titers, complement activation and CMV-related immune dysregulation can converge to produce a life-threatening SJS/TEN-like phenotype. Early B-cell-directed therapy combined with immunoglobulin can be life-saving, and prolonged oncological surveillance remains warranted.