Accurate histological terminology for small intestine carcinoid tumors.

The recent WHO Classification of Tumours of the Digestive System reflects the views of a Working Group that convened for an Editorial and Consensus Conference at the International Agency for Research on Cancer (IARC), Lyon, 10 December 2009 [1]. In this classification, the “neuroendocrine neoplasms of the small intestine” include neuroendocrine tumor (NET), neuroendocrine carcinoma (NEC), mixed adenoneuroendocrine carcinoma, EC cell, serotonin-producing NET, gangliocytic paraganglioma, gastrinoma, L cell, glucagon-like peptide-producing, PP/PYY-producing NETs, and somostatin-producing NET. “Carcinoid tumor” is the generic term traditionally applied to low-grade malignant neoplasms originating from the diffuse endocrine system exclusive of the pancreas and the thyroid C-cell, a term being progressively replaced by “well-differentiated (neuro)endocrine tumors/carcinomas”. It is now acknowledged that they represent a group of related neoplasms, not single pathologic entity. In the WHO classification, the NET includes NET G1 and NET G2, and the term “carcinoid” is used as a synonym of NET G1. We believed that the term “carcinoid tumor” is generic; consequently, the term should be avoided. We have read with great interest the paper by Lee et al. – “Multiple carcinoid tumor of the small intestine preoperatively diagnosed by double-balloon endoscopy” [2]. In the paper, Lee et al. wrote: We believe that the histological diagnosis of carcinoid tumor is not correct. The description is typical of NET G1, according to the new WHO classification. The authors wrote: It is evident that histological diagnosis was not reported. In conclusion, accurate histological diagnosis is necessary for the evaluation of treatment impact in the management of neuroendocrine tumors of the small intestine.