Is it possible to discriminate pulmonary carcinoids from hamartomas based on CT features?

The purpose of this study was to determine whether the computed tomography (CT) features might be used in distinguishing pulmonary carcinoids from hamartomas.

Ninety solid pulmonary nodules (43 carcinoids and 47 hamartomas) in 90 patients were evaluated. The following CT scan features were evaluated: size, location (peripheral/central), contour (lobulated/nodular), number of lobulation, attenuation, calcification, endobronchial status, bronchial extension and involvement, parenchymal abnormalities distal to the lesion e.g. hyperlucency, atelectasis, and nodularity. The final pathologic diagnosis of the lesions and bronchial extension were confirmed by review of histopathological specimens.

Out of 43 carcinoids, 37 (86%) were typical. Twenty-three carcinoids and four hamartomas were central (p < 0.001). Ten carcinoids and one hamartoma were endobronchial. The majority of tumors had lobulated contours (65% of carcinoids, 44% of hamartomas) and carcinoids tended to have more lobulations (p = 0.052). Distal nodularity (p = 0.001), distal hyperlucency (p < 0.001), and atelectasis (p = 0.005) were significantly more common in carcinoids. Carcinoids had significantly more bronchial extension and involvement (p < 0.001; respectively). In addition, a new sign that we call "bronchial triangle sign" differentiated carcinoids with a sensitivity and specificity of 84.9% (95% CI: 69,1%-93.4%) and 91% (95% CI: 79.7%-96.6%).

To the best of our knowledge this is the first study on discrimination of carcinoids and hamartomas. A new CT sign called "bronchial triangle sign" might be used to differentiate carcinoids from hamartomas. Distal parenchymal abnormalities are more common in carcinoids than in hamartomas.