Histological Diagnosis and Frequency of Primary Endocrine Tumors (ETs) and Neuroendocrine Tumors (NETs) According to WHO Classification

The new who classification provides the foundation for tumor diagnosis, patient treatment and tools for clinicoepidemiologicalresearch. this study was conducted to determine the frequencyand update the histological aspects of different endocrine and neuroenodocrine tumors for clinical significance and to minimize unclassified lesions. materials and methods: five hundred biopsieswere analyzed in the pathology department of king edward medical university from 1st june 2004 to 31st december 2005. tumors were diagnosed with light microscopy using the new who classification.results: following 500 biopsies, 145 (29%) endocrine(et) and neuroendocrine tumors (net) were found; majority of the former, et, n=112 (77.2%), were in the thyroid, of which 84 (75%) were follicular adenomas and 28 (25%) were carcinomas, of the 28 carcinomas, the frequencies were: papillary carcinoma (pc) 21 (75%); anaplastic(ac) 4(14.28%); follicular(fc) 2 (7.14%); and medullary (mc) 1 (3.57%). of the 145, 33 (22.8%) were neuroendocrine tumors (net), with the following types and frequencies: adrenal 13 (39.5%); pituitary 10 (30.5%);pancreatic 4 (12%); parathyroid 3(9%); appendix 1 (3%); and rectum 1 (3%). one net detected in the thyroid region was a well-differentiated neuroendocrine carcinoma (wdnec). among adrenal nets, of13 only 2 (14.4%) were malignant and diagnosed as a cortical and a neuroblastoma respectively, while all others were benign nets, as follows: cortical adenoma 2 (15.38%); pheochromocytoma 7 (53.8%) and 1 (7.69%) ganglio neuroblastoma, and ganglioneuroma each respectively. all pituitary, parathyroid and pancreatic nets were benign in nature. nets of the appendix and rectum were wdnets, whilethat of the lung was a wdnec. findings of this study confirm that the who classification provides uniform, simple, reproducibleand practical criteria for diagnosis of ets and nets.