Anatomic Laparoscopic Partial Hepatectomy of a Segment 4a B-Catenin Mutated Adenoma.

Background: Although a β-catenin mutated hepatocellular adenoma (HCA) is a benign liver tumor, it can cause bleeding, obstruction, pain, and hepatocellular carcinoma. Because surgery needs to balance these risks with its morbidity, a minimally invasive approach may be well suited. In this report, a strategic approach to minimally invasive resection of HCA encompassing segment 4a (S4a) is reviewed.

Patient: A 22-year-old woman with abdominal pain was found to have two liver lesions involving segment 4a (5 cm) and segment 8 (S8) (4.5 cm). Liver biopsy confirmed a β-catenin mutated HCA in the S4a lesion. After embolization, an anatomic S4a segmentectomy and a partial S8 resection were planned.

Technique: Three-dimensional modeling was used to perform a preoperative virtual hepatectomy; to visualize the spatial relationship between the HCA, the portal bifurcation, and the hepatic veins; and to preplan the port sites. With the patient in the French position, after port placement, intraoperative ultrasound was performed to identify the transection plane. The main left portal pedicle and Rex's recessus were exposed, and the branches of S4a were dissected out, clipped, and divided. Using ultrasound, the middle hepatic vein was exposed to define the lateral border of the dissection plane.

Conclusion: Although a β-catenin mutated HCA in S4a does not necessitate a formal segmentectomy, understanding the anatomic structures outlining its borders can facilitate the resection, especially for a large HCA. Virtual hepatectomy helps to achieve a detailed comprehension of the complex borders of segment 4a. Preoperative embolization can firm up the tumor and minimize the risk of intraoperative rupture from manipulation.