Long-term growth of intrahepatic papillary neoplasms: A case report

BACKGROUND Intraductal papillary neoplasm of the bile duct (IPNB) is a type of tumor that presents in the intra- or extrahepatic bile ducts. Cystic-type intrahepatic IPNB often mimics simple liver cysts, making the diagnosis difficult. Because the growth of IPNB is slow, careful follow-up and timely therapeutic intervention is recommended. There are few reports with a follow-up period longer than a decade; thus, we report the case of a patient with an IPNB that grew for over 13 years. CASE SUMMARY A 65-year-old man was diagnosed, 13 years prior with a cystic hepatic tumor with abnormal imaging findings. The targeted tumor biopsy results showed no malignancy. Biannual follow-up examinations were performed because of the potential for malignancy. The cystic lesions showed gradual enlargement over 11 years and a 4 mm papillary proliferation appeared on the cyst wall, which is compatible with IPNB. The tumor was observed for another 2 years because of the patient's wishes. The imaging findings showed enlargement to 8 mm and a new 9 mm papillary proliferation of the cystic tumor. Contrast-enhanced ultrasonography showed hyperenhancement during the arterial phase in both cyst wails, indicating intraductal tumor progression in both tumors. Thus, liver segment 8 subsegmentectomy was performed. The pathological findings indicated that the tumors contained mucin, and high-grade atypia was observed in the papillary lesions, showing IPNB. CONCLUSION The development of IPNB should be monitored in patients with cystic lesions and ultrasonography are useful tool for the evaluation.