Retroperitoneal Fibrosis Presenting With Duodenal Obstruction: A Fatal Case of Corticosteroid-Resistant Disease.

Retroperitoneal fibrosis is a fibro-inflammatory condition characterised by the development of dense tissue within the retroperitoneum, which may result in the compression of adjacent structures. We report the case of a 69-year-old woman with a history of breast cancer who initially presented with right-sided hydronephrosis. Cross-sectional imaging demonstrated retroperitoneal soft tissue encasing the ureters, consistent with retroperitoneal fibrosis. She underwent unilateral ureteric stenting followed by bilateral nephrostomy insertion and was commenced on corticosteroid therapy. Following review at a national specialist centre, a variant of idiopathic retroperitoneal fibrosis was diagnosed. She was subsequently re-admitted with progressive complications including deep vein thrombosis, nephrostomy site bleeding, and Staphylococcus epidermidis bacteraemia. During this admission, the patient developed progressive upper gastrointestinal symptoms, including early satiety and vomiting. Computed tomography demonstrated gastric and proximal duodenal dilatation with tethering of the distal duodenum, consistent with duodenal obstruction. Endoscopy confirmed external compression at the third part of the duodenum. Despite escalation to high-dose intravenous corticosteroids and supportive management, her condition deteriorated with refractory vomiting, electrolyte imbalance, fluid overload, and respiratory compromise. She was deemed unsuitable for surgical or endoscopic intervention and was transitioned to palliative care, dying eight months after her initial presentation. This case demonstrates a challenging clinical course of retroperitoneal fibrosis complicated by duodenal obstruction and highlights the complexities of diagnosis and management when extra-urological involvement develops.