A Rare Etiology for an Endobronchial Lesion

Solitary pulmonary nodules are a frequent finding at thoracic imaging studies. Most solitary pulmonary nodules are the result of malignancy-either primary lung malignancies or solitary metastases-or infections, particularly granulomatous infections. Lesions arising from a bronchus are less common causes of solitary pulmonary nodules at thoracic imaging studies; most such lesions represent malignancies arising from the airways, such as carcinoid tumors and minor salivary gland tumors. Primary endobronchial neoplasms, both benign and malignant, often have a similar appearance at imaging studies, particularly thoracic computed tomography, presenting as a lobulated, polypoid lesion associated with an airway, possibly associated with postobstructive effects, such as pneumonia, atelectasis, or gas trapping. Malignant endobronchial lesions may also show more aggressive features, such as locally invasive behavior, regional lymphadenopathy, or even metastatic disease. A host of rare tumors may arise within the lung parenchyma and bronchi. One such rare lesion-pneumocytic adenomyoepithelioma-has only been recently described. This tumor resembles other minor salivary gland neoplasms showing epithelial and myoepithelial features but, uniquely, also shows pneumocytic differentiation. Little is known of the clinical and imaging features of this rare submucosal gland bronchial tumor.