# An Intrahepatic Fluorodeoxyglucose (FDG)-PET/CT False-Positive Tumor Secondary to Foreign Body Granuloma Masquerading as Colon Cancer Liver Metastasis: A Case Report

## TL;DR

A suture left during liver surgery caused a false-positive cancer signal on a PET/CT scan, leading to unnecessary treatment.

## Contribution

Highlights an unusual case where a surgical suture caused a false-positive PET/CT result, mimicking cancer recurrence.

## Key findings

- A silk suture from a prior hepatectomy caused FDG accumulation in the liver, resembling a metastasis.
- The granuloma formed around the suture was resected, confirming it was not cancerous.
- This case underscores the need to consider foreign body granulomas in follow-up imaging after hepatic surgery.

## Abstract

A suture placed next to a dissected liver section during the initial hepatectomy may become an unlikely intrahepatic foreign body granuloma. In this report, we describe a case where a silk suture in the liver section plane placed during initial hepatectomy for synchronous colon cancer metastasis became an intrahepatic foreign body granuloma that exhibited fluorodeoxyglucose (FDG) accumulation on positron emission tomography/computed tomography (PET/CT). The granuloma was resected as the second metachronous liver metastatic lesion. A 73-year-old female was referred for a planned second hepatectomy. She had undergone colectomy and hepatectomy for advanced cancer of the ascending colon and synchronous liver metastasis approximately two years ago. However, two possible liver metastases with FDG accumulation were identified in hepatic segments IV and V after one year and nine months after the initial resection. A second hepatectomy was planned after administering systemic chemotherapy. She underwent a left lobectomy with a middle hepatic vein and partial segment V hepatectomy six months after liver lesion identification. The segment IV lesion was histologically proven to be a liver metastasis adenocarcinoma. The segment V lesion revealed a silk thread on the residual liver side at the initial hepatectomy, which was histologically diagnosed as a foreign body granuloma. The possibility of intrahepatic foreign body granuloma development should be considered in subsequent follow-ups in cases where sutures were applied to the dissected residual liver plane during the initial hepatectomy. Additionally, a thorough second hepatectomy should be considered if recurrence is suspected.