Immunohistochemical diagnostic of neuroendocrine tumors of the gastrointestinal tract (review of the literature and own data)

Summary. Neuroendocrine tumors (NET) of the digestive tract asi very important problem. Morphological study is main in the diagnostisc of NET and further treatment strategy. Morphological diagnosis of NET is based on the WHO classification and evaluation criteria of prognosis NET. The main in morphological diagnostic of the NEP is immunohistochemistry (IHC) using markers to establish the nature of NET, and markers for determining the potential malignancy. The analysis of contemporary literary publications devoted to the diagnostics of NET, led to the conclusion that verification of the NET is advisable to use a combination of immune markers such as chromogranin A, synaptophysin, CD56, and for identify the proliferative activity — Ki-67, p53 and AMACR. To date, according immunohistochemical study, NET classified as follows: 1) highly differentiated tumors with low-grade of malignancy — NET G1; 2) highly differentiated tumors with an intermediate degree of malignancy — NET G2; 3) poorly differentiated tumors with a high degree of malignancy (neuroendocrine carcinoma — NEC). IHC makes it possible to determine the localization of primary NET when first diagnosed metastases. For this purpose it is necessary to use IHC markers: SDX2 — intestinal localization; PDX, ISL1, PAX8 — markers of pancreatic origin. To determine the metastatic potential it is necessary to use the marker CD44. It is shown three cases of morphological diagnosis NEP appendix, pancreas and rectum from own practice.