Chest Imaging

Carcinoid tumour, pulmonary

a part of the spectrum of neuroendocrine lung neoplasms. It is a low-grade primary malignant lung cancer having generally a good prognosis. Pathologically, carcinoid tumours are characterized by the presence of small cells organized in nests or trabeculae with a vascular stroma and containing neurosecretary granules. Carcinoid tumours are characterized as either typical or atypical. Typical tumours rarely metastasize, by contrast to atypical that exhibit metastases in 40-50% of cases, particularly osteoblastic bone metastases. There is no association with cigarette smoking. Common clinical symptoms include cough and haemoptysis. Carcinoid tumours may be associated with ectopic ACTH production.

Most of these tumours manifest as an endobronchial small nodule or obstructing lesion associated with atelectasis, obstructive pneumonitis, or air trapping (bronchial stenosis (V:1), Fig. 1). This bronchial obstructionmay result in a focal mucoid impaction. In other cases, they may extend extraluminally resulting in a so-called iceberg lesion appearing radiographically as a hilar or perihilar mass (Fig.1). Approximately 20% of carcinoid tumours occur in the periphery of the lung and manifest as a solitary pulmonary nodule. Calcifications are frequently depicted on CT scans, particularly in central tumours. These neoplasms are characteristically extremely vascular, and as a result frequently show a marked contrast enhancement following intravenous contrast administration. Also, see carcinoid syndrome and carcinoid gastrointestinal.

 

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Fig.1

Contrast-enhanced CT showing a well circumscribed round mass located behind the right hilum. This mass enhanced significantly after iodinated contrast media because of high vascularity (a). This mass obstructs the lumen of the superior segmental bronchus of the right lower lobe. This results in distal bronchiectasis (b).
Carcinoid tumour, pulmonary, Fig.1 (a)
Carcinoid tumour, pulmonary, Fig.1 (b)