Bronchial carcinoid tumors are an uncommon group of pulmonary neoplasms that are characterized by neuroendocrine differentiation and relatively indolent clinical behavior. Although originally referred to as bronchial adenomas, these tumors are now recognized as malignant neoplasms because of their potential to metastasize.
Like carcinoid (neuroendocrine) tumors at other body sites, bronchial carcinoids are thought to derive from peptide- and amine-producing neuroendocrine cells that have migrated from the embryologic neural crest. Carcinoids can arise at a number of sites throughout the body, including the thymus, lung, gastrointestinal tract, and ovary. The gastrointestinal tract is the most frequently involved site, while lung is the second most common. (See "Clinical characteristics of carcinoid tumors".)
The epidemiology, classification, clinical features, diagnosis, and staging of bronchial carcinoid tumors will be reviewed here. Treatment and prognosis of bronchial carcinoid tumors, as well as clinical characteristics of carcinoid tumors arising in other sites, are discussed elsewhere. (See "Bronchial carcinoid tumors: Treatment and prognosis" and "Clinical characteristics of carcinoid tumors".)
EPIDEMIOLOGY AND RISK FACTORS
Bronchial carcinoid tumors account for approximately 1 to 2 percent of all lung malignancies in adults and roughly 20 to 30 percent of all carcinoid tumors [1-4]. Bronchial carcinoids are the most common primary lung neoplasm of children, typically presenting in late adolescence. Typical carcinoids, which are low-grade tumors with a low mitotic rate, are about four times more common than atypical carcinoids, which are intermediate-grade tumors with a higher mitotic rate and/or necrosis. (See 'Classification, histology, and histochemistry' below.)
Globally, incidence rates range from 0.2 to 2 per 100,000 population per year, and most series suggest a higher incidence in women as compared to men, and in whites as compared to blacks [1-3,5-7].