Benign tumor, bronchogenic cyst, pulmonary hamartoma, pulmonary sequestration, bronchiectasis, and arteriovenous malformation (AVM) are the principal benign and acquired conditions of the lung encountered in thoracic surgery. This chapter reviews the etiology, clinical presentation, diagnosis, and therapeutic modalities for these benign and acquired conditions. Established surgical techniques are described in the ensuing chapters of this section.
Bronchogenic cysts are thought to be congenital lesions that arise from the primitive foregut. They are usually found within the mediastinum or lungs. The mediastinal lesions can be found close to the carina, main stem bronchi, trachea, esophagus, or pericardium. Bronchogenic cysts of the skin and subcutaneous tissue are also reported.
The precise embryonic pathway leading to the development of bronchogenic cysts is still unknown. The respiratory tree develops by an outpouching of the primitive foregut. Some have theorized that this process fails when a cyst develops in place of the mature structure. As with other structures of the bronchus, bronchogenic cysts are lined by ciliated columnar or squamous epithelial cells (respiratory and gastrointestinal). Mucus-secreting bronchial glands found in the epithelium cause the cysts to fill. As the cysts grow, pressure is exerted on surrounding structures, particularly the membranous trachea or bronchi, which may lead to severe respiratory obstruction. Cartilage and smooth muscle cells are also found in the cyst wall.
Symptoms may be evident in both children and adults depending on many factors such as the presence of a communication between the lumen of the cyst and the airways, infection of the fluid within the cyst, and bleeding. If the cyst grows large enough to cause obstruction in adjacent structures, the main symptoms will be cough, dyspnea, dysphagia, and chest pain of varying degrees as a result of irritation of the airways and esophagus or inflammation of the mediastinal or parietal pleura. Infectious complications may cause symptoms of high body temperature, elevated leukocyte count, and cough with purulent sputum. Pneumonia localized to the pericystic parenchyma may accompany chronically recurring cysts. Hemoptysis is a sign of an ulcerative process in the cyst wall. Rare complications include cardiac arrhythmias, superior vena cava syndrome, and cancer.
Plain chest radiographs are diagnostic only when the cavity of the cyst contains an air-fluid level. This finding, especially when the cyst is located in the mediastinum, excludes enterogenous cysts from the differential diagnosis. Plain chest radiography alone can diagnose accurately approximately 80–90% of cases and is useful for initial screening.1
CT scanning and MRI give greater detail regarding anatomic and topographic localization, especially with respect to surrounding structures. These imaging modalities also provide detail about wall composition and content of the cysts (Fig. 79-1).
CT scan showing a large bronchogenic ...