Isolated jejunal amyloidosis presenting as acute mechanical small bowel obstruction: a rare diagnostic challenge - a case report.

Introduction: Gastrointestinal (GI) involvement in amyloidosis is uncommon and usually occurs as part of systemic disease. Localized jejunal amyloidosis is exceptionally rare and may mimic neoplastic or inflammatory disorders because of its nonspecific presentation. Case presentation: A 77-year-old man with no significant medical history presented with acute abdominal pain, distension, and bilious vomiting. Contrast-enhanced CT demonstrated jejunal obstruction associated with circumferential wall thickening and multiple intraluminal polypoid lesions. Enteric magnetic resonance imaging confirmed these findings, suggesting an infiltrative lesion. Enteroscopy revealed multiple jejunal polypoid lesions, and biopsies demonstrated Congo red-positive amyloid deposition. Extensive investigations excluded systemic amyloidosis, establishing localized jejunal amyloidosis. Owing to symptomatic mechanical obstruction, the patient underwent segmental jejunal resection with primary anastomosis. Histopathology confirmed localized amyloid infiltration. Recovery was uneventful, and at 6-month follow-up the patient remained asymptomatic without recurrence. Discussion: Localized jejunal amyloidosis causing true mechanical bowel obstruction is exceedingly rare. This case highlights the diagnostic challenge posed by nonspecific imaging and endoscopic findings and emphasizes the importance of histopathological confirmation. Conclusion: Amyloidosis should be considered in the differential diagnosis of unexplained small bowel obstruction. Surgical resection provides both definitive diagnosis and effective treatment in obstructive localized disease.