Two Cases of Gastrointestinal Stromal Tumor of the Lesser Omentum

Abstract

(Case 1) A 76-year-old man was treated for prostate cancer. Follow-up computed tomography (CT) revealed a heterogeneous tumor at the border between the stomach wall and lesser omentum. The tumor demonstrated 18-F-fluorodeoxyglucose (FDG) uptake, with a maximum standardized uptake value (SUVmax) of 3.7. Colonoscopy revealed a simultaneous rectal adenoma with surgical indication. We performed laparoscopic resection of the tumor located in the lesser omentum and laparoscopic low anterior resection. The tumor in the lessor omentum was 60 mm in diameter and was fed by the left gastric artery. We were able to resect the whole tumor without breakage, and it was histologically diagnosed as a gastrointestinal stromal tumor (GIST) of the lesser omentum.

(Case 2) A 65-year-old woman underwent a complete medical checkup, in which laboratory examination showed a high level of serum CA19-9. CT revealed an irregularly shaped, heterogenous bulky mass located on the ventral side of the gastric body. FDG positron emission tomography revealed FDG accumulation, with an SUVmax of 4.9. Endoscopic ultrasound - guided fine - needle aspiration biopisy was performed ; based on the results, we diagnosed a GIST that was weakly positive for c-kit and positive for CD34. Due to the size, we performed laparotomy. The tumor was 150 mm in diameter and located in the lesser omentum. There was an adhesion with the stomach wall and greater omentum that did not combine with the gastric wall. We were able to completely resect the specimen without breakage.

Cases 1 and 2 both involved high-risk GISTs of the lesser omentum. Although the patients refused adjuvant chemotherapy, patients 1 and 2 have been living without recurrence for 31 months and 109 months, respectively.