Genomic analysis of an aggressive case with metastatic intrahepatic mucinous cholangiocarcinoma.

Intrahepatic mucinous cholangiocarcinoma (IHMC) is rare and behaves notoriously; however, the details of the clinicopathological characteristics of IHMC remain unknown. A 70-year-old man was admitted for examination of the hepatic mass in the S1 segment. He underwent extended left hepatic lobectomy. Histopathological evaluation demonstrated mixed papillary carcinoma that comprised well to moderately differentiated tubular adenocarcinoma and signet-ring cell carcinoma with large amounts of mucus lakes. Tumor was relapsed 9 months after surgery. Although he received chemotherapy with the combination of gemcitabine and cisplatin, he had renal failure and discontinued the chemotherapy. He received palliative radiotherapy for metastasis in the cervical spine. Then, the patient treated with S-1, however, he died 16 months after the initial diagnosis. The autopsy findings showed multiple nodules in the lungs, pleura, kidneys, adrenal glands, stomach, pancreas, and lymph nodes. Histological examination revealed that all nodules were IHMC. Next-generation sequencing revealed that somatic mutations in ADGRB3, TAF1L and EPHA3 may affect carcinogenesis, and those in TAF1, EPHA3, PIK3C2B, FN1, ERBB3, BRIP1, SYNE1 and TGFBR2 may affect metastasis. Molecular carcinogenesis of IHMC may be distinct from that of ordinary cholangiocarcinoma. Further studies are needed to elucidate the genetic mutations and their functions in IHMC.