Roughly 90% of all carinal resections are performed for airway neoplasms. The true incidence of primary tracheal tumors is undetermined, but they are extremely rare. In one series of 1744 cancer deaths, only 2 were attributed to tracheal malignancy, whereas in 89,600 autopsies, only four tracheal tumors were found.1 The carinal tumor is a subcategory of tracheal tumors and hence even less common. Most carinal tumors are malignant and are categorized as bronchogenic carcinoma or other airway neoplasms. Bronchogenic carcinomas are, by definition, malignant. Other airway neoplasms may exhibit a wide range of behavior. As shown in Table 56-1, the most common histologies are squamous cell carcinoma (SCC) and adenoid cystic carcinoma (ACC).2 These are the two most common malignant primary tracheal neoplasms. SCC arises primarily in smokers in the sixth and seventh decades. On presentation, the mass is either confined to the trachea or there may be invasion into adjacent mediastinal structures.
Table 56-1. Histologic Types of Carinal Neoplasms from a Single Institution, 1962–1996. |Favorite Table|Download (.pdf)
Table 56-1. Histologic Types of Carinal Neoplasms from a Single Institution, 1962–1996.
Bronchogenic carcinoma (n = 58)
Squamous cell carcinoma
Large cell carcinoma
Small cell carcinoma
Other airway neoplasms (n = 60)
Adenoid cystic carcinoma
Malignant fibrosing histiocytoma
Mixed spindle cell carcinoma
Granular cell tumor
ACC is an exophytic intratracheal lesion that to a variable extent involves the tracheal wall (Fig. 56-1). Initially, the mass may compress the mediastinal structures without direct invasion. Lymph node metastasis is less common in ACC than in SCC. A characteristic feature of ACC is its proclivity to extend for long distances submucosally and perineurally.
Adenoid cystic carcinoma invading through the anterior carinal wall into the mediastinal space and abutting the superior vena cava.
Patients with carinal tumors commonly present with symptoms and signs of central airway obstruction. As the diameter of the airway decreases, patients begin to experience worsening dyspnea, often progressing to wheezing and stridor. Dyspnea on exertion occurs when the airway diameter is less than 8 mm, and stridor develops when the airway is less than 5 mm.3 Chest radiographs may demonstrate a mass in the tracheobronchial airway column, but these findings are often subtle and usually missed. Consequently, patients are commonly misdiagnosed with adult-onset asthma, and the true diagnosis is delayed. Diagnosis may be facilitated in patients presenting with postobstructive pneumonia or cough with hemoptysis. Extensive tumors may be heralded by hoarseness, dysphagia, or chest discomfort, suggesting a more diffuse or extensive mediastinal invasion.