Gastrointestinal stromal tumors with atypical features and presentations: A case series

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors to affect the digestive tract. These tumors arise from the interstitial cells of Cajal. Although the majority of GISTs occur in the stomach, they can arise anywhere along the GI tract, including the small intestine, colon, esophagus, and very rarely from extra intestinal locations. GISTs mainly affect older adults, with a slight male preponderance. Small size GISTs can be discovered incidentally during imaging or endoscopy. Symptoms vary depending on the location and size of the tumor, those related to the tumor mass effect (abdominal pain, discomfort, distension and a palpable mass), or others presenting with anemia and GI hemorrhage. Contrast-enhanced abdomino-pelvic CT scan is the investigation of choice for staging and follow-up. GISTs are distinguished from other tumors using immunohistochemical test positivity for CD 117and CD 34. Surgery is the standard treatment for localized GISTs followed by risk stratification. Adjuvant imatinib should be considered in all patients with significant risk of recurrence following resection of primary GISTs.

Here we describe a series of GISTs presenting at atypical locations, unique presentations, and atypical histologic variants. The first case was a 35-years old female patient who underwent an emergency laparotomy for small bowel obstruction and later diagnosed to have a mesenteric GIST (an extraintestinal GIST). The second case was a 60-year-old male patient who underwent an emergency laparotomy for a small bowel obstruction secondary to an intrabdominal mass and later diagnosed to have a jejunal GIST. The third case was a 72 years old male patient who underwent exploratory laparotomy for gastro-gastric intussusception secondary to gastric GIST. The fourth case was a 55 years old male patient who underwent exploratory laparotomy for gastric GIST with liver secondaries. In immunohistochemistry examination, all were positive for CD 117.

Clinical presentation of GISTs depend on the tumor size and location. Small tumors are usually asymptomatic. If symptomatic, the most common clinical manifestations are features of anemia, GI bleeding, compressive symptoms, and intestinal obstruction. The diagnosis of GIST is confirmed using tissue histology and immunohistochemistry tests.

Even though GIST constitutes the smallest portion of GI neoplasms, physicians need to have high index of suspicion for it in patients presenting with vague abdominal pain and consider abdominopelvic CT as part of patients' work up.