Abstract
Sclerosing mesenteritis is a rare spectrum of disease that results in chronic inflammation and fibrosis of the abdominal mesentery. Its heterogeneous presentation, nondiagnostic imaging, and pathology findings make diagnosis challenging. In this study, we present the first reported case of hilar sclerosing mesenteritis resulting in chylous ascites, gastric outlet obstruction, and duodenal perforation. Diagnosis was made after extensive investigations including computed tomography imaging, magnetic resonance cholangiopancreatography, positron emission tomography scan, bidirectional endoscopy, endoscopic ultrasound, and diagnostic laparoscopy. While initially mistaken for hilar cholangiocarcinoma, the patient has significant clinical improvement with corticosteroids and now remains in symptomatic and radiographic remission on low-dose prednisone and tamoxifen.