RESUMEN
BACKGROUND: Pemphigus vulgaris (PV) is a potentially life-threatening mucocutaneous autoimmune disease that affects desmoglein-1 and desmoglein-3, leading to intraepithelial vesiculobullous lesions. In the oral mucosa, PV lesions can mimic other diseases such as mucous membrane pemphigoid, other forms of pemphigus, recurrent aphthous stomatitis, erythema multiforme, Stevens-Johnson syndrome, and virus-induced ulcers like herpes simplex virus (HSV), making diagnosis challenging. The co-occurrence of PV with Crohn's disease is rare and predominantly seen in younger patients. The therapeutic mainstay for both PV and Crohn's disease usually involves systemic corticosteroids combined with immunosuppressants and immunobiological drugs. Literature indicates that the use of these drugs, particularly TNF-alpha inhibitors, for managing autoimmune diseases like Crohn's can potentially induce other autoimmune diseases known as autoimmune-like syndromes, which include episodes of lupus-like syndrome and inflammatory neuropathies. There are few cases in the literature reporting the development of PV in individuals with CD undergoing infliximab therapy. CASE REPORT: A young female with severe Crohn's disease, treated with the TNF-alpha inhibitor infliximab, developed friable pseudomembranous oral ulcerations. Histopathological and immunofluorescence analyses confirmed these as PV. The treatment included clobetasol propionate and low-level photobiomodulation, which resulted in partial improvement. The patient later experienced severe intestinal bleeding, requiring intravenous hydrocortisone therapy, which improved both her systemic condition and oral lesions. Weeks later, new ulcerations caused by herpes virus and candidiasis were identified, leading to treatment with oral acyclovir, a 21-day regimen of oral nystatin rinse, and photodynamic therapy, ultimately healing the oral infections. To manage her condition, the gastroenterologists included methotrexate (25 mg) in her regimen to reduce the immunogenicity of infliximab and minimize corticosteroid use, as the patient was in remission for Crohn's disease, and the oral PV lesions were under control. CONCLUSION: Young patients with Crohn's disease should be referred to an oral medicine specialist for comorbidity investigation, as oral PV and opportunistic infections can arise during immunosuppressive therapy. The use of TNF-alpha inhibitors in patients treated for inflammatory bowel disease, such as Crohn's, should be carefully evaluated for potential side effects, including oral PV.