Neuroendocrine tumors of gastrointestinal tract with special reference to immunohistochemistry markers at a tertiary care hospital

Abstract

Background: Neuroendocrine tumors (NETs) are epithelial neoplasms that originate from the endocrine cells, contain cytoplasmic granules, and secrete a variety of biogenic amines, which are responsible for a variety of signs and symptoms produced by these tumors. Endocrine cells are interspersed within the mucosa of the gastrointestinal tract (GIT) and are also present in a variety of other viscera such as pancreas, adrenal gland, lung, and thyroid. The present study included forty cases of NETs of the GIT (excluding pancreas) reported in the Department of Pathology at Sher-i-Kashmir Institute of Medical Sciences (SKIMS), Srinagar, Kashmir. The objectives of this study were to study the histopathological spectrum of NETs of the GIT and to evaluate the immunohistochemical (IHC) expression of chromogranin, synaptophysin (SYP), neuron-specific enolase, and Ki-67 (MIB) in these tumors. Materials and Methods: The study was conducted at the SKIMS, Srinagar, Kashmir, in the Department of Pathology. It was a prospective study for a period of 1½ years starting from July 2015 to December 2016 and retrospective study for 3½ years from January 2012 to June 2015. The study included all cases of NETs of GIT with or without nodal metastasis. Results: Most of the tumors were well-differentiated NETs (45% G1 and 25% G2). Stomach was the most common site (27.5%) followed by duodenum (25%). Regional lymph node involvement was present in 25% of the cases. Liver was the most common site for distant metastasis. There was a slight female predominance (57.3%). On IHC, SYP, chromogranin-A, and neuron-specific enolase were positive in 100%, 77.5%, and 85% of cases, respectively. Ki-67/MIB-1 index was used to grade the neuroendocrine neoplasms and 45% were graded as G1 NETs, 25% as G2 NETs, and 30% as NEC. Conclusion: Lately, there has been a surge in the number of cases being diagnosed as NETs most probably due to advancement in various diagnostic modalities and increasing knowledge about these tumors which have helped in diagnosing more of these tumors early and correctly.