Follicular cholangitis mimicking cholangiocarcinoma treated with right hepatectomy: a case report and review of the literature

Follicular cholangitis is a new, rare disease that causes severe biliary stricture. We herein describe the findings from a resected case of follicular cholangitis, suggesting a distinct disease entity that causes benign biliary stricture. A 60-year-old man who was referred to our hospital due to elevated gamma-glutamyl transpeptidase levels and dilatation of the B8 bile duct. Although bile juice cytology and bile duct brushing cytology showed no malignancy, the dilatation was progressive. Therefore, right hepatectomy combined with caudate lobectomy was carried out on suspicion of intrahepatic cholangiocarcinoma. The wall of the resected bile duct was markedly thickened due to severe fibrosis under the mucosal layer. Histology of the mucosal epithelium indicated no malignancy. Infiltration of plasma cells characterized by remarkable formation of lymphoid follicles with germinal centers was observed around the bile ducts. The patient was diagnosed with follicular cholangitis based on histological findings. We thus observed a rare case of follicular cholangitis. This case and review of published reports suggest that, despite its rarity, follicular cholangitis should be considered at the differential diagnosis of biliary stricture. This case report could contribute to a better understanding of how to address this disease.