| Abstract: |
Neuroendocrine lesions of the lung include neuroendocrine cell hyperplasia and tumorlets, and a spectrum of pulmonary neuroendocrine tumors that includes the low-grade typical carcinoid (TC), intermediate-grade atypical carcinoid (AC), and the high-grade tumors of large cell neuroendocrine carcinoma (LCNEC) and small cell carcinoma (SCLC). Diffuse idiopathic neuroendocrine cell hyperplasia is a very rare condition that represents a pre-invasive lesion for carcinoid tumors. Despite the common neuroendocrine properties of TC, AC, LCNEC, and SCLC, there are major clinical, epidemiologic, and genetic differences between carcinoid tumors and the high-grade SCLC and LCNEC. Both TC and AC can occur in patients with Multiple Endocrine Neoplasia (MEN) type I but LCNEC and SCLC do not. In contrast to LCNEC or SCLC, both TC and AC can have associated neuroendocrine cell hyperplasia with or without tumorlets. Also, both LCNEC and SCLC can demonstrate histologic heterogeneity with other major histologic types of lung carcinoma, such as adenocarcinoma or squamous cell carcinoma, but is not characteristic of TC or AC. The diagnosis of SCLC, TC, and AC can be made by light microscopy without the need for special tests in most cases, but for LCNEC it is required to demonstrate neuroendocrine differentiation by immunohistochemistry or electron microscopy. Finally, genetic changes are very high in SCLC and LCNEC, but usually low for TC and intermediate for AC. © 2010 Springer-Verlag New York. |
