Gastrointestinal stromal tumor pathophysiology

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Parminder Dhingra, M.D. [2]

Overview

On microscopic histopathological analysis, spindle cells or plump epithelioid cells are characteristic findings of gastrointestinal stromal tumor.

Pathophysiology

• GISTs are thought to arise from interstitial cells of Cajal (ICC), that are normally part of the autonomic nervous system of the intestine. They serve a pacemaker function in controlling motility.

• GISTs are believed to arise from the interstitial cells of Cajal, with 95% staining positive for CD117 (c-KIT) and 70% for CD34. The former is a tyrosine kinase growth factor receptor and the target of ST-571 (Imatinib; Glivec).

• Grading GISTs requires assessment of both tumour size and mitotic index. Smaller lesions have less aggressive biological behaviour, as do stomach GISTs when compared to tumours elsewhere along the gastrointestinal tract.

• Macroscopically these tumours are rounded with frequent haemorrhagic change. Larger tumours also may demonstrate necrosis and cystic change. Size is variable ranging form 1 to 30cm.

• Histology demonstrates a relatively cellular tumor comprised of spindle cells (70-80%) and or plump epithelioid cells (20-30%). They appear to arise from the muscularis propria layer.

Gastrointestinal stromal tumor of stomach. Courtesy of Ed Uthman, MD.

Endoscopic image of GIST in fundus of stomach, seen on retroflexion.

Same GIST seen on forward view of the endoscope showing overlying clot.

References

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