Gastrointestinal stromal tumors (GISTs) are uncommon mesenchymal neoplasms.
However, while some tumors metastasize, others may remain asymptomatic for years.
It is difficult to distinguish between them histologically.
In this study, researchers from Hungary analyzed the characteristics of 7 metastasizing GISTs, and compared clinicopathological parameters of the metastatic and non-metastatic groups.
Histology revealed typical GIST features with spindle, epithelioid, or mixed appearance.
|Tumors in the metastatic group were significantly larger than those in the non-metastatic group.|
|Journal of Clinical Pathology|
The team found that all 7 cases were positive for vimentin, 5 for neurone specific enolase, 6 for c-kit, 4 for S-100, 3 for PGP-9.5, and 3 for CD-34 and synaptophysin.
All were negative for cytokeratin, neurofilament, chromogranin A, and desmin.
In addition, 4 showed a focal reaction for smooth muscle actin.
The team determined that 3 of the tumors were GI, and 2 each were GII and GIII.
They also found that the Ki-67 index varied from 4% to 44%, and the 3 GI cases had 4%, 10%, and 16%.
The researchers determined that tumors in the metastatic GIST group were significantly larger than those in the non-metastatic group.
Dr Tornóczky's team concluded, "Three cases exhibited bland, GI histological features with moderate or low proliferative activity".
"Among the c-kit positive metastasizing stromal tumors, some were low grade, with moderate or low mitotic and Ki-67 indices".
This emphasizes the need, "To develop a reliable grading system for GIST to predict clinical behavior…and the key role of c-kit status in identifying patients who could benefit from treatment with STI-571".
"Larger tumors had a higher chance of metastasizing, and only the size of the primary tumor played a role in predicting metastatic potential".