Sweet's syndrome during anti-TNF therapy with successful rescue using a JAK inhibitor in refractory ulcerative colitis: a case report and literature review.

Objective: This report describes the diagnostic and therapeutic management of Sweet's syndrome (SS) presenting as a painful forehead plaque in a patient with refractory ulcerative colitis (UC) during apparent endoscopic remission. It highlights the association between active intestinal inflammation and extraintestinal manifestations (EIMs) and evaluates the efficacy of the Janus kinase (JAK) inhibitor upadacitinib after anti-TNF therapy failure. Methods: A case study was conducted on a 60-year-old woman with refractory UC who presented with new-onset cutaneous lesions accompanied by fever. Diagnostic evaluation included skin biopsy histopathology, comprehensive microbiological cultures, serological testing, and sequential colonoscopies to assess UC activity. Results: Histopathology revealed a dense neutrophilic infiltrate highly suggestive of SS. Infectious etiologies were ruled out. Repeat colonoscopy revealed active colitis in the setting of newly diagnosed SS. After infliximab failure, upadacitinib 45 mg/day led to pain resolution within one week and complete plaque healing by week 8, with mucosal healing and normalized inflammatory markers at follow-up. Maintenance with 30 mg/day sustained remission. Conclusion: Active UC may drive severe neutrophilic EIMs such as SS, even when prior endoscopy suggests remission. Re-assessment of bowel disease activity is crucial in this context. Upadacitinib rapidly controlled both conditions in this anti-TNF-refractory case, supporting JAK inhibition for similar overlapping immune-mediated presentations.