Small Intestinal Tumours: an Overview on Classification, Diagnosis, and Treatment

The small intestinal neoplasia group includes different types of lesions and are a relatively rare event, accounting for only 3-6% of all gastrointestinal (GI) neoplasms and 1-3% of all GI malignancies. These lesions can be classified as epithelial and mesenchymal, either benign or malignant. Mesenchymal tumours include stromal tumours (GIST) and other neoplasms that might arise from soft tissue throughout the rest of the body (lipomas, leiomyomas and leiomyosarcomas, fibromas, desmoid tumours, and schwannomas). Other lesions occurring in the small bowel are carcinoids, lymphomas, and melanomas. To date, carcinoids and GIST are reported as the most frequent malignant lesions occurring in the small bowel. Factors that predispose to the development of malignant lesions are different, and they may be hereditary (Peutz-Jeghers syndrome, familial adenomatous polyposis, hereditary non-polyposis colorectal cancer, neuroendocrine neoplasia Type 1, von Hippel-Lindau disease, and neurofibromatosis Type 1), acquired (sporadic colorectal cancer and small intestine adenomas, coeliac disease, Crohn’s disease), or environmental (diet, tobacco, and obesity). Small bowel tumours present with different and sometimes nonspecific symptoms, and a prompt diagnosis is not always so easily performed. Diagnostic tools, that may be both radiological and endoscopic, possess specificity and sensitivity, as well as different roles depending on the type of lesion. Treatment of these lesions may be different and, in recent years, new therapies have enabled an improvement in life expectancy.