Giant gastrointestinal stromal tumor of the vermiform appendix: A case report

Gastrointestinal Stromal Tumour of the Appendix: A Very Rare Entity

A 74-year-old man who presented with upper abdominal pain was found to have an incidental appendiceal mass on cross-sectional imaging. He underwent a laparoscopic appendicectomy with histopathological examination confirming a completely resected appendiceal gastrointestinal stromal tumour (GIST). Appendiceal GISTs are rare. Therefore, there is limited evidence to guide risk stratification and management with extrapolation of prognosis from data on GISTs at other sites. This paper highlights the rarity of these tumours and presents another case which correlates well with the existing but limited literature. There is a need to maintain a registry of this rare disease entity with the maintenance of longer-term follow-up data.

Gastrointestinal stromal tumors (GISTs) arising in uncommon locations: clinicopathologic features and risk assessment of esophageal, colonic, and appendiceal GISTs

Risk stratification of gastrointestinal stromal tumors (GISTs) is based on experience with tumors of the stomach, small bowel, and rectum, which are far more common than GISTs of other sites. In this study from 47 institutions, we analyzed GISTs of the esophagus (n = 102), colon (n = 136), and appendix (n = 27) for their size, mitotic rate, morphology, and outcome to determine which criteria predict their behavior. Esophageal GISTs were small (median: 2.5 cm) with spindle cell morphology and a low mitotic rate (mean: 3.6/5 mm²). Twelve (12%) tumors progressed, including 11 with a mitotic rate >5/5 mm² and one large (6.8 cm) GIST with a mitotic rate of 2/5 mm². Colonic GISTs were smaller (median: 1.4 cm) and presented with abdominal pain or bleeding in 29% of cases. Most (92%) were composed of spindle cells with a mean mitotic rate of 4.6/5 mm². Sixteen (12%) tumors progressed: 14 had mitotic rates >5/5 mm², and two were >5.0 cm with a mitotic rate <5/5 mm². All but one appendiceal GIST measured <2.0 cm. These tumors were composed of spindle cells with low mitotic rates (<5/5 mm²), and none progressed. Our results suggest that progression risk among esophageal and colonic GISTs is associated with increased mitotic activity (>5/5 mm²) and size >5.0 cm. These findings support the use of size and mitotic rate for prognostication of GISTs in these locations, similar to tumors of the stomach, small bowel, and rectum.