High mitotic index associated with poor prognosis in gastrointestinal autonomic nerve tumour

Aims: Three gastrointestinal autonomic nerve tumours (GANT) were characteri zed by immunohistochemistry and flow cytometry. Two of the three cases occu rred in the small intestine, while the third was found in the stomach. Besi des the immunohistochemical and ultrastructural description, the aim of thi s study was to examine the relation between the known and accepted predicti ve factors (ploidy data, the S-phase fraction, the mitotic and MIB-1 index and the size of the tumour) and the survival of the patients. Methods and results: The immune profile showed that 3/3 cases were vimentin and NSE, 2/3 were synaptophysin and PGP 9.5 positive, while 1/3 also showe d S100 positivity, Ultrastructurally, all the cases had dense core granules , one of them contained skenoid fibres. The flow cytometry revealed diploid DNA in all cases, however significant differences could be seen in the pro liferative activity of the individual neoplasms. Conclusions: In spite of the published data of gastrointestinal stromal tum ours (GIST) generally, neither the MIB-1 index: and the ploidy data nor the size of the primary tumour helped to predict the clinical progression of t he examined GANTs. However, the high proliferative activity (57 mitoses/10 HPF) and the elevated S-phase fraction (24%) was associated with advanced, metastatic and recurring disease in case 3. On the basis of these three cas es, high mitotic activity is the most reliable factor in predicting aggress ive clinical behaviour.