Comparative radiological pathological study of biliary intraductal tubulopapillary neoplasm and biliary intraductal papillary mucinous neoplasm.

PURPOSE: Biliary tract intraductal tubulopapillary neoplasms (BT-ITPNs) and intraductal papillary mucinous neoplasms (BT-IPMNs) are rare and poorly described. Herein, we examined the magnetic resonance imaging (MRI) features of BT-ITPNs and BT-IPMNs and correlated them with key gross and microscopic pathological findings.

METHODS: We retrospectively identified five patients with definitive pathological findings of BT-ITPN and available diagnostic MRI findings. Key MRI features were correlated to the gross and microscopic pathology and compared to those of BT-IPMNs (19 patients).

RESULTS: All BT-ITPNs showed ductal dilatation and visible intraductal soft tissue with peribiliary liver parenchyma enhancement. One BT-ITPN patient had synchronous lung metastases, and another showed rapid tumor growth rate. The intraductal soft tissue proportion of BT-ITPNs was significantly more than that of BT-IPMNs (p < 0.05). CA-199 level was elevated in 60% of BT-ITPN cases. The overall combined 1-year and 3-year survival rates in the BT-ITPN group was 100% and 40%, and in the BT-IPMN group was 100% and 58%, respectively. A high intraductal soft tissue proportion, a lack of intraluminal mucin, and immunohistochemical absence of MUC5AC are radiological and pathological characteristics that differentiate BT-ITPN from BT-IPMN.

CONCLUSIONS: Although rare, BT-ITPN should be suspected when solid intraductal soft tissue and peribiliary liver parenchyma enhancement are present, particularly if the bile duct upstream and downstream of the lesion have a normal diameter, without mucin. Owing to the aggressive nature of the tumor, recognition of these features may indicate the need for more aggressive treatment in selected patients.