# A Case of Solitary Fibrous Tumor of the Greater Omentum Incidentally Detected during Preoperative Evaluation for Thyroid Cancer

## TL;DR

A rare case of a solitary fibrous tumor in the greater omentum was discovered during preoperative testing for thyroid cancer and successfully treated with laparoscopic surgery.

## Contribution

This paper reports a rare case of SFT originating from the greater omentum and highlights the challenges in its diagnosis and treatment.

## Key findings

- A 28 mm tumor was laparoscopically removed and diagnosed as a solitary fibrous tumor.
- The tumor showed no atypical cells and had clear resection margins.
- SFT from the greater omentum is extremely rare and lacks established treatment guidelines.

## Abstract

Solitary fibrous tumor (SFT) is a mesenchymal tumor and accounts for less than 2% of all soft tissue tumors. It is most commonly found in the pleura and has a relatively good prognosis.

A 53-year-old woman was diagnosed with thyroid cancer and underwent a plain CT scan for preoperative examination. A mass measuring 23 mm in maximum diameter was incidentally found near the greater curvature of the stomach. Although its continuity with the stomach was unclear, an additional 18F-fluorodeoxyglucose positron emission tomography (FDG-PET)/CT scan revealed abnormal accumulation of Sstandardized uptake value (SUV) of max 4.2 at the same site. Percutaneous biopsy and endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) were anatomically difficult, so a laparoscopic resection was performed as a diagnostic treatment. The specimen measured 28 mm in maximum diameter and was elastically hard. There was a proliferation of small- to medium-sized spindle cells, and no atypical cells were observed. No tumor components were found at the resection margin. The diagnosis of SFT was therefore made. The patient was discharged 2 days after surgery. Although it would have been difficult to diagnose the tumor based on preoperative imaging alone, we were able to perform minimally invasive tumor removal by laparoscopic surgery and make a diagnosis.

Although the prognosis of SFT is generally good, its treatment has not been established. In particular, SFT originating from the greater omentum is extremely rare. We report this case along with some relevant literature.