A case report: mucinous carcinoma of extrahepatic bile ducts with periportal calcification suggestive of lymphatic calcification

Mucinous carcinoma is a rare subtype of extrahepatic bile duct (EHBD) cancer in which abundant mucin surrounds cancer cell nests. Calcification is often observed in mucus-producing tumors, and we herein report a case of mucinous carcinoma of EHBD with diffuse periportal calcifications. A 92-year-old woman was seen for jaundice. Non-contrast CT showed diffuse semi-linear branching calcifications extending from the hepatoduodenal ligament along the long axis of the intra- and extrahepatic portal veins. A bile duct mass and multiple lymph nodes were hyperintense on T2-weighted MRI images, and periportal abnormal intensity was visible along the intrahepatic portal tract. On contrast-enhanced CT, the mass and enlarged lymph nodes showed a weak enhancing effect. In addition, a lesion with a similar enhancing effect was observed in parallel with periportal calcification, raising suspicion of tumor extension. An endoscopic bile duct biopsy was performed, which resulted in the tumor being diagnosed as a mucinous carcinoma. Considering the imaging findings, it was determined to be a mucinous carcinoma of EHBD origin, with lymphatic vessel infiltration and multiple lymph node metastases. The lymphatic tracts presented lymphangitic carcinomatosis extending from the hepatoduodenal ligament to intrahepatic portal tracts, and the diffuse periportal calcification was presumed to be calcification associated with the mucin component of tumor infiltration.