Extra-gastrointestinal stromal tumor with a large cyst

Abstract

Gastrointestinal stromal tumors (GISTs) arising at sites other than the alimentary tract are rare, and they are called extra-GISTs (EGISTs). We report a case of a large EGIST forming a cyst, probably arising in the mesentery of the transverse colon. A 64-year-old Japanese man presented to a hospital with an abdominal tumor forming a large cyst. Intraoperatively, the tumor was neither present in nor in contact with the alimentary tract. It was present in the mesentery of the transverse colon and was attached to the greater omentum and peritoneum, immediately anterior to the body of the pancreas. The tumor was resected with the spleen and a part of the pancreas. Histological examination of the tumor revealed that it belonged to the high-risk category of cystic EGISTs.

Extragastrointestinal stromal tumour (EGIST) presented as a mesenteric and retroperitoneal mass

“…EGIST has its origin outside the gastrointestinal tract and has histopathological characteristics similar to GIST, hence its name. It is a very rare entity, representing 1% of all gastrointestinal malignancies and about 5%–10% of all GISTs 1 2 5–7. A mean age of 45.8–59 years has been reported, and women are more affected than men 4 5 7…”

“…A growing abdominal mass is a common finding, with tumours reaching up to 32 cm in size (mean of 10 cm) 3. Cystic degeneration of an EGIST has also been reported and must be considered in the differential diagnosis of abdominal cystic lesions 6. The mesentery, retroperitoneum, omentum, pancreas, liver, gall bladder, urinary bladder, pleura, prostate, seminal vesicles, pelvis and vagina are possible locations of EGIST, while the entire gastrointestinal tract can be affected by GIST 1–3.…”

“…One major problem when dealing with EGIST is that there is no consensus on grading, management and prognosis. While tumour size and mitotic count dictate the grading and prognosis of GIST, these are not yet valid in EGIST, although there are some authors who use in EGIST the same approach used for GIST 6 7. The only data available is that EGIST has an early age of onset, has usually a larger tumour, is more aggressive and has a worse prognosis than GIST.…”

“…Extragastrointestinal stromal tumour (EGIST) occurs outside the gastrointestinal tract and has histopathological and molecular characteristics similar to gastrointestinal stromal tumour (GIST), hence its name 1–7. Reith et al 4 from Florida, USA, were the first to use the name EGIST in 2000 3.…”

“…Reith et al 4 from Florida, USA, were the first to use the name EGIST in 2000 3. It is a very rare entity, representing less than 1% of all gastrointestinal malignancies 1 2 5 6. Because it has non-specific clinical presentation and is difficult to differentiate from other pathologies on imaging findings, its preoperative diagnosis is not common 1 2.…”