Neuroendocrine Neoplasms of the Lung

Neuroendocrine tumors (NETs) represent a heterogeneous group of neoplasms with a morphologic spectrum that ranges from well-differentiated tumors such as typical carcinoids of the lung, intermediate-grade neoplasms like atypical carcinoids, and high-grade or poorly differentiated tumors such as small cell lung carcinoma and large-cell neuroendocrine carcinoma. These tumors comprise 25% of primary lung neoplasms and are thought to arise from specialized neuroendocrine cells that form a part of the epithelial lining of the bronchial tree. These cells, known as pulmonary neuroendocrine cells (PNECs) or Kulchitshy cells, are phylogenetically ancient and believed to be of endodermal origin. They are also found in the gastrointestinal tract. The management and prognosis of pulmonary neuroendocrine tumors vary widely. In this chapter, we will discuss the clinical, radiological, and pathological correlates of the spectrum of neuroendocrine neoplasms of the lung to provide information that can be directly applied to clinical practice.