RADIOLOGY: LUNG: Case# 14: BRONCHIAL CARCINOID. 17-year-old female with asthma who presented with opacified left hemithorax on chest x-ray. Bronchoscopy, with rigid bronchoscope, showed left main stem bronchial occlusion. There is complete atelectasis of the left lung. This is an obstructive type atelectasis with bronchially dilated fluid-filled bronchograms seen throughout the lungs. Fluid-filled bronchograms are seen to the level of the left main stem arising near the carina. A small to moderate size pleural effusion is seen surrounding the left lung. There has been shift of the mediastinum towards the left slightly. This is most evident on the lower mediastinum. There are no enlarged mediastinal lymph nodes identified. The right lung appears normal without any air space opacities or pleural abnormality. Bronchial carcinoid tumors are relatively rare, accounting for approximately 5% of primary lung tumors. They may range from low-grade malignant typical carcinoid, which has a 5-year survival rate of 90%, to atypical carcinoid which is highly associated with metastases and has a 5-year survival rate of 50%. Bronchial carcinoid is classified as a neuroendocrine tumor although paraneoplastic syndromes associated with bronchial carcinoid are rare. Most are centrally located, well-circumscribed masses arising within the major bronchi. Metastases may occur in the liver, bone, and adrenal glands. The typical appearance on CT is a smooth or lobulated soft-tissue mass within a main or lobar bronchus. Atypical carcinoids usually have more irregular margins and inhomogeneous contrast enhancement. Mediastinal and hilar lymph node metastases may be present with atypical carcinoid. Carcinoid may sometimes be distinguished from bronchogenic carcinoma by the presence of small punctate peripheral calcifications or marked contrast enhancement.