[Neuroendocrine tumors of the lungs. From small cell lung carcinoma to diffuse idiopathic pulmonary neuroendocrine cell hyperplasia].

The new World Health Organization (WHO) classification announced for 2015 will for the first time present all neuroendocrine tumors (NET) of the lungs in one single section. In this classification high grade small cell lung carcinoma (SCLC) and large cell neuroendocrine carcinoma (LCNEC) will be discriminated from intermediate grade atypical carcinoid (AC) and low grade typical carcinoid as well as from the preinvasive lesion diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH). The LCNEC was previously listed under the section of large cell carcinomas. The LCNEC could previously be diagnosed according to the current WHO classification from 2004 which is designed for resection specimens. According to this the main diagnostic criteria are a neuroendocrine growth pattern which can be difficult or impossible to detect in biopsy material, non-small cell cytological features, more than 10 mitoses per 2 mm(2) (mean 70-80 per 2 mm(2)), tumor cell necrosis, and an immunohistochemical positivity for at least one neuroendocrine marker other than neuron-specific enolase (NSE). The presentation of all neuroendocrine tumors of the lungs in one section allows a more direct comparison and a better differential diagnostic discrimination of the different entities.