AJR:197, November 2011
Quinn Colin Meisinger Jeffrey S.Klein Kelly J. Butnor George Gentchos Bruce J. Leavitt
OBJECTIVE. Pulmonary carcinoid tumors are low-grade malignant neoplasms thought to arise primarily within the central airways in 85% of cases. The CT features of pulmonary carcinoid tumors that arise as solitary pulmonary nodules (SPNs) have not been well eluci¬dated. We reviewed our experience with primary pulmonary carcinoid tumors to determine the distribution of lesions within the lung at diagnosis and to identify CT features that might aid in distinguishing these neoplasms from benign pulmonary nodules.
MATERIALS AND METHODS. CT scans, if available, of all patients with a primary pulmonary carcinoid tumor diagnosed by biopsy or surgical resection over the previous 15 years were reviewed. The CT scans were reviewed for the following features: lesion location; order of bronchus involved; lesion size, contour, and density; contrast enhancement; and the presence of peripheral atelectasis, hyperlucency, and bronchiectasis. We defined central le¬sions as those involved with a segmental or larger bronchus. Subsegmental bronchial involve¬ment and tumors surrounded by lung parenchyma without direct airway involvement were defined as peripheral lesions. The final pathologic diagnosis for all cases was confirmed by review of cytologic or histologic specimens.
RESULTS. Twenty-eight carcinoid tumors were identified in 28 patients: 24 typical car¬cinoids and four atypical carcinoids. The study group was composed of 23 females and five males with a mean age of 52.4 years (range, 14-83 years). Twelve of the 28 lesions (43%) were central (i.e., involved a segmental or larger bronchus), and the remaining 16 lesions (57%) were peripheral. The mean tumor diameter for the 16 peripheral tumors was 14 mm (range, 9-28 mm); the majority (14/16, 88%) had a lobulated contour. Of six peripheral le¬sions with unenhanced and contrast-enhanced CT nodule enhancement studies, the mean maximal enhancement was 55.2 HU (range, 34-73 HU). Thirteen of the 16 peripheral carci-noid tumors (81%) involved a subsegmental bronchus, with 10 (63%) showing peripheral hy-perlucency, bronchiectasis, or atelectasis.
CONCLUSION. In our series, primary pulmonary carcinoid tumors presenting as pe¬ripheral SPNs were more common than central endobronchial lesions in contrast to the pub¬lished literature. The CT features of peripheral carcinoid tumors presenting as SPNs that sug¬gest the diagnosis include lobulated nodules of high attenuation on contrast-enhanced CT; nodules that densely enhance with contrast administration; the presence of calcification; sub-segmental airway involvement on thin-section analysis; and nodules associated with distal hyperlucency, bronchiectasis, or atelectasis.