RESUMEN
INTRODUCTION: Fibroinflammatory biliary stricture (FIBS) is a rare benign tumor-like process of the extrahepatic bile duct that masquerades as cholangiocarcinoma. METHODS: In order to distinguish this unusual entity from cancer, we performed a systematic analysis of 11 patients with FIBS. All patients presented with jaundice; six patients had coexisting autoimmune disease. Preoperative evaluation included computed tomography scan and endoscopic retrograde cholangiopancreatography with benign brush cytology. Surgical treatment included nine bile duct resections with five concurrent liver resections and two incisional biopsies. Light microscopy demonstrated fibrous lesions admixed with chronic inflammation. RESULTS AND DISCUSSION: Immunohistochemistry demonstrated smooth muscle actin expression in all lesions except one; five tumors exhibited IgG4 positive plasma cells. The lesions were negative for cytokeratin, ALK1, CD21, S100, Ki67, and p53. Six patients received postoperative immunosuppression. At 41 month median follow-up (range 15-58 months), there was no evidence of recurrent FIBS in ten patients, while one was lost to follow-up. CONCLUSION: FIBS is a rare myofibroblastic lesion with an immunohistochemical profile distinct from other epithelial and stromal neoplasms of the extrahepatic bile duct. A subset of these cases appear to represent IgG4-related sclerosing cholangitis. Because preoperative cytology is not diagnostic of FIBS, surgical resection remains the mainstay of diagnosis and treatment, while immunosuppression may reduce the risk of recurrence.