Clinicopathologic study of neuroendocrine tumors of gastroenteropancreatic tract: a single institutional experience.

BACKGROUND: The gastroenteropancreatic neuroendocrine tumors (GEPNET) have a characteristic histologic appearance unrelated of the exact site of origin. However the behavior of these tumors are different in each of these sites. In this article we study the clinicopathological features of GEPNET. These tumors were classified and graded according to WHO 2010 criteria. The immunohistochemical (IHC) features were evaluated and the grade of the tumor was correlated with Ki67.

METHODS: A total of 40 cases of GEPNET diagnosed on biopsies as well as resected specimens were analyzed from January 2012 to June 2015.

RESULTS: There were 28 resected specimens and 12 biopsies. Majority of the gastric neuroendocrine tumors (NET) showed classic morphology of cells arranged in islands. There were 3 cases each of grade 1 and grade 2 and one was diagnosed as mixed adenoneuroendocrine carcinoma (MANEC). All the duodenal NET were well differentiated (grade 1). There were 8 cases in colon and rectum, of which 4 cases were grade 3 and 3 cases were grade 2. Majority of the pancreatic tumors were grade 1. The mean mitotic count along with ki67 had good correlation in NET of stomach, duodenum colon and rectum.

CONCLUSIONS: The most common site was small intestine followed by pancreas. Majority of the tumors were NET G1. Tumors from colorectal region were mostly NEC G3. There was a strong correlation by spearman correlation analysis between Ki67 and mitotic count and moderate correlation between ki67 and tumor grade as well as mitotic rate and tumor grade. Ki67 was helpful in grading these tumors.