We encountered a case of successful laparoscopic surgery performed for giant HHC with an enhancing mural nodule that was clinically suspected of being biliary cystadenocarcinoma.
Laparoscopic liver resection (LLR) has rapidly gained acceptance over the past decade as a viable treatment for several malignant and benign hepatic diseases, given its prominent advantages over an open approach with regard to post-surgical pain relief, better cosmetic results, and a shorter hospital stay due to the smaller surgical wound and less bleeding. The recent international consensus is that minor LLR is a safe and feasible procedure that is superior to an open approach for select patients; in contrast, major LLR remains a technically demanding procedure, and its safety, feasibility and preliminary evidence are still limited .
At our institute, we have expanded the indication for LLR as we accumulate experience, and laparoscopic-assisted extended right hepatectomy was completed with sufficient surgical and oncological safety in the present case. Remarkable surgical techniques applied in this case included the shrinkage of the cyst and the hanging maneuver technique. First, we carefully removed the cyst contents without any spillage because shrinkage of the cyst was necessary in order to create an intraabdominal working space. We were subsequently able to mobilize the right lobe of the liver laparoscopically. Second, the hanging maneuver technique was effective for ensuring the safe performance of parenchymal division through the small laparotomy wound (7 cm), as this technique makes it possible to pull up the liver so that the resection line comes just beneath the laparotomy wound .
Previous studies have discussed the imaging characteristics of HHCs; however, they still remain challenging to describe [1,2,3,4,5]. Very recently, Kohno et al. summarized the imaging characteristics of HHCs with enhancing mural nodules . In all the resected cases in the literature, the nodules were histologically diagnosed with neovascularization within organized hematoma, as was observed in our case. As they mentioned, the ventral enhancing mural nodule in our series showed persistent centripetal filling on delayed CT images and central high signal intensity on T2WI. In addition, the calcification of the cyst wall was found close to the dorsal mural nodule. However, unlike their report, the ventral mural nodule in the present case demonstrated a weak but abnormal uptake on FDG-PET. This abnormal uptake on PDG-PET may have been associated with the high Ki-67 value. Previous studies have shown that the SUVmax on FDG-PET was correlated with the Ki-67 index of various tumors [10, 11]. Considering that the ventral mural nodule rapidly grew within a year, it is conceivable that the nodule included highly proliferating endothelial cells. Moreover, we found a high signal intensity area on DWI with a low ADC value on MRI in the ventral mural nodule, and this was retrospectively considered to be consistent with organized hematoma. However, these MRI findings were also observed in biliary cystadenocarcinoma, which led to the preoperative misdiagnosis.
Because HHC is a rare and heterogeneous entity, its cause and pathogenesis have not been fully discussed. In the present case, we hypothesize that giant HHC was formed as a result of repeated rupture of venous malformation and that neovascularization developed reactively in association with the thrombus undergoing organization. Hepatic hemangioma with cyst formation has been also reported as a rare condition [12, 13], and our case bore some similarities to this entity. However, the dilated vessels in the ventral mural nodule were immunohistochemically negative for αSMA and EVG, indicating reactive angiogenesis mimicking cavernous hemangioma.