CoCC is a rare liver tumor accounting for 0.6–1% of primary liver tumors and was first reported by Steiner and Higginson in 1959 [1, 2]. CoCC is derived from the canals of Hering, or cholangioles, where hepatic progenitor cells are located . A previous report describing the pathological features of 20 cases CoCC noted that macroscopically, all cases were of the MF type . Curative hepatectomy for CoCC is reported to be associated with a higher 5-year survival rate (75%) in comparison to ICC, with liver metastasis being the most frequent pattern of recurrence (75%) . There is currently no established therapy for hepatic recurrence of CoCC; however, repeat hepatectomy has been reported to be an effective treatment for patients with limited hepatic recurrence of HCC and ICC [6, 7]. Given that repeat hepatectomy has been reported to be associated with good long-term outcomes in some cases involving hepatic recurrence of CoCC [10, 11], aggressive surgical resection is considered to be an effective treatment, as it is for other liver tumors. It is also reported that surgical resection for intraductal growth (IG type) recurrence of HCC and ICC prolongs the survival time of patients [10, 12]. Considering the relatively low malignant potential of CoCC, aggressive surgical treatment for IG type recurrence may also be acceptable. However, at present, there is no established strategy for managing recurrent CoCC; thus, systemic chemotherapy and radiation treatment can be applied in cases of distant recurrence. Further investigations are necessary to determine the validity of this approach.
Given the low liver function of the present patient at the time of the first operation, we considered that he would not be able to tolerate both right lobectomy and anterior segmentectomy; thus, S8 segmentectomy was performed as the only feasible surgical procedure. As a result, IG-type recurrence developed 8 months after the first surgery. Considering his remnant liver function, we deemed further surgery difficult; however, a slow-growing recurrent tumor gradually blocked the posterior branch of the portal vein and subsequently reduced the blood flow, causing the right liver lobe volume to shrink while the remnant left liver lobe volume increased. The clinical course in this case was similar to that observed in patients after portal vein embolization (PVE). PVE is a procedure in which the portal vein in the part of the liver that is to be resected is embolized in advance of a surgery to induce the regrowth of the remnant liver. This procedure allows the patient to have a sufficient liver function after the operation.
The macroscopic growth pattern of the tumor differed between the two operations. The former pattern was MF type, whereas the latter was IG type. The reason for this change in macroscopic features was unclear; however, the primary tumor infiltrated the peripheral intrahepatic bile duct (b1) in the vicinity of the hepatic radial margin, and immunohistochemistry of the recurrent tumor revealed the high expression of Ki-67 (14.5%). These findings may have contributed to the change in the growth pattern and the relatively early recurrence.
We used the remnant liver volume and ICG Krem value as indices to indicate the performance of extended right lobectomy with bile duct resection. The remnant liver volume could be calculated using multi-detector row helical CT and was determined to be 52% in this case. ICG Krem is determined by multiplying the disappearance rate of indocyanine green by the ratio of the remnant liver volume to the total liver volume. In patients with a low liver function, a preoperative ICG Krem value of ≥ 0.05 indicates that major hepatectomy can be safely performed . In the present case, the patient’s ICG Krem value was 0.058. The only postoperative complication was ascites (Clavien–Dindo grade II), which suggests that both remnant liver volumetry and the calculation of the ICG Krem value were useful for assessing the risk of postoperative liver failure.