Follicular cholangitis: a rare cause of benign biliary stricture

Introduction: The differential diagnosis of focal biliary strictures comprises both malignant and benign conditions. We report a rare case of follicular cholangitis presenting with segmental stricture of the left hepatic duct. Case description: An asymptomatic 59-year-old male with no past medical history presented with dilation of the left intrahepatic bile ducts revealed as an incidental finding on an abdominal ultrasound. Blood examinations showed only a slightly elevated gamma- glutamyl transferase (gammaGT) value, while carbohydrate antigen 19-9 (Ca 19-9) and serum immunoglobulin G4 (IgG4) were within normal range. Abdominal computed tomography and magnetic resonance imaging/magnetic resonance cholangiopancreatography (MRI/MRCP) scans revealed a high grade focal intrahepatic stricture of the left hepatic duct (FIHS type III) with proximal dilatation. Given that a diagnosis of cholangiocarcinoma could not be ruled out, the patient was referred for a left hepatectomy with regional lymph node dissection. Histological analysis showed a lymphoplasmacytic infiltration of the left hepatic duct with fibrosis and follicle formations in the submucosa, findings consistent with follicular cholangitis. The postoperative course was uneventful and there is no evidence of recurrence 8 months after the surgery. Discussion: The clinical and imaging presentation of follicular cholangitis is very similar to cholangiocarcinoma, rendering it a challenging diagnosis preoperatively. Conclusion: The approach to these cases should be primarily surgical. Even though it is very rare -- our report is the 13th case reported worldwide -- follicular cholangitis should be included in the differential diagnosis of focal biliary strictures.