24 Adenoid Cystic Carcinoma

Clinical Presentation

30-year-old woman with cough and stridor

Radiologic Findings

Coned-down PA (Fig. 24.1A) and coned-down lateral (Fig. 24.1B) chest radiographs demonstrate a well-defined ovoid mass within the distal tracheal lumen. Unenhanced chest CT (mediastinal [Fig. 24.1C] and lung [Fig. 24.1D] windows) demonstrates an endoluminal spherical soft-tissue mass arising from the posterolateral tracheal wall that almost completely obstructs the airway lumen. There is circumferential tracheal wall thickening that suggests local invasion.

Fig. 24.1

Diagnosis

Adenoid Cystic Carcinoma

Differential Diagnosis

• Mucoepidermoid Carcinoma

• Carcinoid

• Squamous Cell Carcinoma

• Other Mesenchymal Neoplasms (benign or malignant)

Discussion

Background

Primary tracheal tumors are rare and occur much less frequently than bronchial tumors. Adenoid cystic carcinoma represents the second most common primary malignant neoplasm of the trachea after squamous cell carcinoma, although some argue that it may be the most common. Adenoid cystic carcinoma and mucoepidermoid carcinoma (another malignant neoplasm that typically affects the proximal bronchi) are primary malignancies of the airway that exhibit histologic features identical to those of primary salivary gland neoplasms of the same name. Adenoid cystic carcinoma may spread into the adjacent mediastinum or neck and may involve regional cervical and mediastinal lymph nodes. Metastases to distant extrathoracic sites are less common.

Etiology

Adenoid cystic carcinoma and mucoepidermoid carcinoma are malignant neoplasms of unknown etiology thought to originate from the submucosal bronchial glands. A relationship between cigarette smoking and these neoplasms has not been identified.

Clinical Findings

Patients with adenoid cystic carcinoma are usually young adults who are typically symptomatic and present with clinical features of airway obstruction, including cough, hemoptysis, and respiratory infection. Rarely, affected patients may present because of symptoms related to distant metastases.