Carcinoid tumors are one of the neuroendocrine tumors (NETs) that derivate from embryonic neural crestand counting for about 2% of primarylung tumors(12).NEcells derived peptides have importantparacrine regulatory and mitogenic function forbronchial epithelial cells.Exposure to pollutants, hypoxia and cigarettesmoking induce hyperplasia of NE- cells in bronchial and cause mucosa secretion. Pulmonary NETs consist of a group of lesions with incidentalfrom small proliferation of neuroendocrine cells to small cell lungcarcinoma. Carcinoid tumorsinclude neuroendocrine-cell hyperplasia lesions that rarely metastasis. Metastasislesions oftenoccur after lung resection. Tumorlets are frequently seen after acute lung injury in eosinophilic granuloma, tuberculosis, interstitial lung disease, cystic fibrosis, Cushing’s syndrome, oblliterative bronchiolitis and bronchiectasis.
