Extra-Gastrointestinal Stromal Tumor of the Greater Omentum: Unusual Case Report

Unusual location of gastrointestinal stromal tumor (GIST): A case report and literature review of greater omentum location

INTRODUCTION

Gastrointestinal stromal tumors (GISTs) represent a unique subset of neoplasms within the digestive tract. They can manifest in various organs throughout the digestive tract, ranging from the oral cavity to the anus, with a predilection for the stomach and small intestine. A distinct subtype of GISTs, known as Extra-gastrointestinal stromal tumors (EGISTs), originate outside the typical GIST organs such as the mesentery, retroperitoneum, and occasionally the omentum. EGISTs are relatively rare, accounting for <5 % of all GIST cases.

PRESENTATION OF CASE

We present the case of a 30-year-old female patient who presented with an upper abdominal mass associated with anorexia, fever, and weakness. Radiographic imaging revealed a cystic mass beneath the left hypochondrium. Exploratory laparoscopy confirmed the presence of an isolated mass adherent to the gastrocolic ligament and greater omentum. Histopathological examination confirmed GIST, characterized by spindle-shaped cells with DOG1 and CD117/C-kit expression. The patient underwent successful tumor resection and was discharged home with postoperative imatinib therapy. Follow-up at 14 months showed no recurrence.

DISCUSSION

The rarity of Gastrointestinal Stromal Tumors (GISTs) in the Greater Omentum highlights diagnostic challenges and underscores the need for further research. Immunohistochemical analysis aids in diagnosis, with Ki-67 staining indicating a high-risk classification. Surgery remains the primary treatment, with potential adjuvant therapy utilizing Imatinib mesylate.

CONCLUSION

Our case underscores the rare occurrence of GIST in the Greater Omentum. Despite their infrequency, EGISTs should be considered in intra-abdominal masses, emphasizing accurate diagnosis for appropriate management and the need for further research.

Clinicopathological features and prognosis of omental gastrointestinal stromal tumor: evaluation of a pooled case series

Clinicopathological features and prognosis of omental GISTs are limited due to the extremely rare incidence. Therefore, the aim of the present study was to investigate the clinicopathological features and prognosis of omental GISTs. Omental GISTs cases were obtained from our center and from case reports and clinical studies extracted from MEDLINE. Clinicopathological features and survivals were analyzed. A total of 99 cases of omental GISTs were enrolled in the present study. Omental GISTs occurred predominantly in greater omentum (78/99, 78.8%). The majority of tumors exceeded 10 cm in diameter (67/98, 68.3%) and were high risk (88/96, 91.7%). Histological type was correlated with tumor location and mutational status. The five year DFS and DSS was 86.3% and 80.6%, respectively. Mitotic index was risk factor for prognosis of omental GISTs. Prognosis of omental GISTs was worse than that of gastric GISTs by Kaplan-Meier analysis. However, multivariate analysis showed that the prognosis was comparable between the two groups. The majority of omental GISTs were large and high risk. Mitotic index was risk factor for prognosis of omental GISTs. The prognosis was comparable between omental and gastric GISTs.