Severe Pancolitis Presenting with Sacroiliitis: A Case Report Highlighting the Gut-Joint Axis in Ulcerative Colitis.

INTRODUCTION: Ulcerative colitis (UC) has a complex multifocal etiology that includes immune dysregulation of the gut microbiome leading to pro-inflammatory cytokine release. UC may present initially through subclinical manifestations such as sacroiliitis due to underlying inflammation, known as the gut-joint axis. JAK inhibition provides an effective treatment method for overlapping intestinal and articular inflammation. CASE PRESENTATION: We describe a 32-year-old man without gastrointestinal symptoms who presented with chronic fatigue and a 2-week history of severe lower back pain. MRI revealed bilateral sacroiliitis, and positive fecal inflammatory markers led to colonoscopy, which showed pancolitis. Further histopathological testing confirmed the diagnosis of UC. He was treated with upadacitinib to address both conditions, resulting in significant improvement in symptoms and inflammatory markers within 2 months. CONCLUSION: This case emphasizes the importance of considering inflammatory bowel disease in uncommon extraintestinal presentation.