A 73-year-old male with previously resected left-sided colorectal adenocarcinoma (pT4aN2a, MSS) status post low anterior resection and adjuvant therapy developed a biopsy-proven hepatic segment 5 metastasis consistent with colorectal origin. Interval cross-sectional imaging and PET also demonstrated a persistent right upper quadrant omental abnormality with mild hypermetabolism, raising concern for regional peritoneal metastatic disease versus inflammatory change. The omental process was not biopsied preoperatively.

He underwent robotic staging laparoscopy to directly evaluate for carcinomatosis and refine candidacy for local therapy. Intraoperatively, a large right omental mass adherent to the anterior abdominal wall was identified and resected with omentectomy, with no other evidence of peritoneal disease. Intraoperative hepatic ultrasound confirmed the known segment 5 lesion and excluded additional liver metastases. Ultrasound-guided microwave ablation was performed to treat the hepatic metastasis with stereotactic targeting, tract ablation, and careful thermal protection of adjacent bowel.

Final pathology from the omentectomy demonstrated fat necrosis with no carcinoma identified, clarifying the etiology of the right upper quadrant finding and confirming absence of diffuse peritoneal spread. The patient recovered well and was discharged home on postoperative day one.