[Pulmonary carcinoid tumors]

Pulmonary carcinoids are rare low-grade malignant tumors, which arise from the neuroendocrine system. Approximately 80% of all pulmonary carcinoid tumors are the relatively low-grade typical carcinoids and 20% are the more aggressive atypical carcinoids. Most carcinoids arise from the central airways and only a minority of carcinoids are found in the lung periphery. While most of the peripheral carcinoids are asymptomatic, central carcinoids are symptomatic and present with hemoptysis, wheezing or bronchial obstruction. On computed tomography (CT), carcinoids frequently present as hypervascular pulmonary nodules in close proximity to the bronchial system. Due to the bronchial obstruction, many patients with pulmonary carcinoids present with post-obstructive pneumonia or atelectasis. While fluorodeoxyglucose positron emission tomography CT (FDG-PET/CT) is of limited value in typical carcinoids due to the high rate of false negatives, somatostatin analogs are promising tracers in staging as well as in the planning of peptide receptor radionuclide therapy.