Perirectal Extragastrointestinal Stromal Tumor: An Unusual Presentation

Abstract

Gastrointestinal stromal tumors (GISTs), even though rare, remain the most common mesenchymal tumors of the gastrointestinal (GI) tract. When GISTs occur outside of the GI tract, they are termed extragastrointestinal stromal tumors (EGISTs). Most GISTs arise from the stomach (50-70%) and small intestine (20-30%). A smaller percentage of these tumors also occurs in the large intestine (5%) and esophagus (2-5%). EGISTs have histopathological and molecular characteristics that are similar to GISTs. However, the precise incidence and tumor behavior of EGISTs are not fully understood. EGISTs have no specific symptoms or radiologic features, and in most cases, the presenting complaint is abdominal pain or discomfort. Yet, they tend to be more aggressive and have a worse prognosis than GISTs. Morphologic diagnosis based on microscopic examination of histological sections is the standard diagnostic procedure for GIST/EGIST. In this patient-centered study, we present a case of EGIST that originated in the anterior perirectal space, an extremely rare location; we also describe the endoscopic approach that was used to biopsy the tumor.

Extra-Gastrointestinal Stromal Tumor (EGIST) in the Pelvis Mimicking Retroperitoneal Sarcoma

“…Subsequently, the pelvic magnetic resonance imaging revealed a 14.5 Â 8.6 Â 8.1cm pelvic heterogeneous exophytic mass that shows heterogeneous T2, mixed hyperand hypo-T1 signal intensities (denoting hemorrhagic components), heterogeneously enhanced and demonstrating areas of restricted diffusion on diffusion-weighted imaging (►Figs. [1][2][3].…”

“…1 The exact incidence of EGISTs and their tumor behavior is unknown. 2 Here, we present a case of EGIST found incidentally in an elderly patient, who was surgically treated and followed by adjuvant oral chemotherapy.…”

“…

Gastrointestinal stromal tumors (GISTs) are among the most common mesenchymal tumors 1 of the gastrointestinal (GI) tract; they account for approximately 3% of all GI tumors, with up to 70% found in the stomach, 25% in the small intestine, 5% in the colon and rectum, and 5% in the esophagus. 2 The cell that gives rise to these tumors is a pluripotent mesenchymal stem cell that has been automated to differentiate into interstitial Cajal cells, 2 which are found in intestinal wall, 3 and regulate its peristalsis. 2 Extra-gastrointestinal stromal tumors (EGISTs), as the term implies, are GISTs found outside the GI tract, 2,3 representing for less than 5% of total GISTs, 3 and less than 1% of total GI tumors.

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“…2 The cell that gives rise to these tumors is a pluripotent mesenchymal stem cell that has been automated to differentiate into interstitial Cajal cells, 2 which are found in intestinal wall, 3 and regulate its peristalsis. 2 Extra-gastrointestinal stromal tumors (EGISTs), as the term implies, are GISTs found outside the GI tract, 2,3 representing for less than 5% of total GISTs, 3 and less than 1% of total GI tumors. 2 EGISTs are most commonly found in the omentum, mesentery, retroperitoneum, pelvic region, abdominal wall, liver, gallbladder, pancreas, bladder, seminal vesicle, vagina prostate, 3 and scrotum.…”

“…2 EGISTs are most commonly found in the omentum, mesentery, retroperitoneum, pelvic region, abdominal wall, liver, gallbladder, pancreas, bladder, seminal vesicle, vagina prostate, 3 and scrotum. 2 The majority of cases involve elderly patients, ranging from 45.8 to 59 years as mean age and are larger than GISTs at the time of diagnosis. 1 EGISTs share histopathological and molecular characteristics with GISTs, 2 but unlike GISTs, some research has shown that EGISTs are derived from Cajal cells or pluripotent stem cells found outside the GI tract.…”