Multifocal Small Bowel Neuroendocrine Tumours.

In contemporary surgical series, the incidence of multifocal tumours (MFT) in small bowel neuroendrocrine tumours (SBNET) is as high as 50%. Familial forms of SBNET appear to have an even higher rate of MFTs in the range of 80%. Multifocal disease poses several challenges and questions for the operating surgeon, including the cause of the disease whether it is local metastases or a genetic field defect, the extent of the resection, and the prognosis. The etiology of these multiple tumours appears to be multifactorial and may represent localized metastases in some, a genetic mutation resulting in the rare familial form of this disease in others, or the integration of genetic and epigenetic events within the bowel. Contrary to historical series, recent data suggest that MFT are not associated with a poorer prognosis. The challenge remains on the long-term surveillance of these unique tumours.