BACKGROUND/AIMS: Grading and staging are important in gastroenteropancreatic neuroendocrine tumors for directing treatment. In this study, we evaluated the histopathological parameters of gastroenteropancreatic neuroendocrine tumors and statistically analyzed the correlations of these parameters between the World Health Organization (WHO) 2000 and 2010 classifications. MATERIALS AND METHODS: A total of 77 cases diagnosed as neuroendocrine tumors were included in the study. Cases were classified according to the WHO 2000 and WHO 2010 classification systems, and the differences and correlations between the two systems were discussed. RESULTS: Among the 50 cases that were diagnosed as well-differentiated neuroendocrine tumor according to WHO 2000, 45 were found to be Grade 1 and 5 were found to be Grade 2 according to the WHO 2010 classification. Among the 8 cases with well-differentiated neuroendocrine carcinoma according to WHO 2000; 5 and 3 were Grade 1 and Grade 2, respectively, according to the WHO 2010 classification. All of the 19 cases with poorly differentiated neuroendocrine carcinoma according to WHO 2000 were found to be Grade 3 according to the WHO 2010 classification. No differences were found between the classifications in the poorly differentiated group with a full correlation between the two classifications. CONCLUSION: Although WHO 2000 seems to be a better classification to predict prognosis, since it is based on various parameters, such as depth of invasion, angiolymphatic invasion, and presence of metastasis, it was concluded that there was no difference between the WHO 2000 and WHO 2010 classification, which is based on only the number of mitoses and Ki-67 proliferation index.
BACKGROUND/AIMS: Grading and staging are important in gastroenteropancreatic neuroendocrine tumors for directing treatment. In this study, we evaluated the histopathological parameters of gastroenteropancreatic neuroendocrine tumors and statistically analyzed the correlations of these parameters between the World Health Organization (WHO) 2000 and 2010 classifications. MATERIALS AND METHODS: A total of 77 cases diagnosed as neuroendocrine tumors were included in the study. Cases were classified according to the WHO 2000 and WHO 2010 classification systems, and the differences and correlations between the two systems were discussed. RESULTS: Among the 50 cases that were diagnosed as well-differentiated neuroendocrine tumor according to WHO 2000, 45 were found to be Grade 1 and 5 were found to be Grade 2 according to the WHO 2010 classification. Among the 8 cases with well-differentiated neuroendocrine carcinoma according to WHO 2000; 5 and 3 were Grade 1 and Grade 2, respectively, according to the WHO 2010 classification. All of the 19 cases with poorly differentiated neuroendocrine carcinoma according to WHO 2000 were found to be Grade 3 according to the WHO 2010 classification. No differences were found between the classifications in the poorly differentiated group with a full correlation between the two classifications. CONCLUSION: Although WHO 2000 seems to be a better classification to predict prognosis, since it is based on various parameters, such as depth of invasion, angiolymphatic invasion, and presence of metastasis, it was concluded that there was no difference between the WHO 2000 and WHO 2010 classification, which is based on only the number of mitoses and Ki-67 proliferation index.