Summary: | <p>Abstract</p> <p>Background</p> <p>Gastrointestinal stromal tumors (GIST) are uncommon intra-abdominal tumors. These tumors tend to present with higher frequency in the stomach and small bowel. In fewer than 5% of cases, they originate primarily from the mesentery, omentum, or peritoneum. Furthermore, these extra-gastrointestinal tumors (EGIST) tend to be more common in patients greater than 50 years of age. Rarely do EGIST tumors present in those younger than 40 years of age.</p> <p>Case presentation</p> <p>We report a case of a large EGIST in a 27-year-old male. An abdominal pelvic computerized tomography imaging demonstrated an intra-abdominal mass of 22 cm, without invasion of adjacent viscera or liver lesions. This mass was resected <it>en bloc </it>with its fused omentum and an adherent portion of sigmoid colon. Pathology results demonstrated a malignant gastrointestinal stromal tumor with positive CD117 (c-kit) staining, and negative margins of resection, and no continuity of tumor with the sigmoid colon. Due to the malignant and aggressive nature of this patient's tumor, he was started on STI-571 as adjuvant chemotherapy.</p> <p>Conclusion</p> <p>Stromal tumors of an extra-gastrointestinal origin are rare. Of the reported omental and mesenteric EGISTs in four published series, a total of 99 tumors were studied. Of the 99 patients in these series only 8 were under 40 years of age, none were younger than 30 years old; and only 5 were younger than 35 years old. Our patient's age is at the lower end of the age spectrum for the reported EGISTs. Young patients who present with an extra-gastrointestinal stromal tumor (EGIST), who have complete resection with negative margins, have a good prognosis. There is little data to support the role of STI-571 in adjuvant or neoadjuvant therapy after curative resection. Given the lack of data, the use of STI-571 must be individualized.</p>
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