대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Tracheal Adenoid Cystic Carcinoma

Radiologic Findings

Chest radiograph ( Fig. 1 ) demonstrates round soft tissue density mass within the trachea 3 cm proximal to carina and hazy pneumonic infiltration in both lower lung zones.

Contrast-enhanced chest CT and 3D reconstruction images (Fig. 2, 3, and 4 ) demonstrate an intraluminal polypoid mass arising from posterior wall with near total obstruction of the tracheal lumen.

Brief Review

Primary tracheal tumors are uncommon, accounting for less than 0.1% of all deaths due to carcinoma. Most primary tracheal tumors in adults ( 50% or more ) are malignant. Squamous cell carcinoma ( 54.5% ) is the most frequent. Adenoid cystic carcinoma ( 18% ) is the second most common primary tumor of the trachea.

Adenoid cystic carcinoma appears to be unrelated to smoking. There is no gender predilection, and the average age of patients is the 5th decade. Symptoms are usually related to airway obstruction. Dyspnea and hemoptysis may occur. Wheezing is a frequent symptom. Patients may be incorrectly diagnosed and treated as asthmatics.

The radiologic appearance of the tumors can be divided into intraluminal wall thickening and exophytic forms. Intraluminal form of the tumors are intraluminal, hemispheric masses limited in spread to the tracheal wall. Wall thickening type manifest as diffuse wall thickening by infiltration of the tumor, and the thickened part presents as either a flat or spindle-shaped mass along the tracheal wall. The exophytic form is radiologically characterized by the extratracheal tumor.

Bronchoscopy is a complementary procedure for diagnosis. The chief advantage of imaging is the demonstration of tracheal wall thickening and extraluminal changes. CT is valuable in demonstrating the primary tumor and its extent. Extraluminal growth in the transverse plane, a common feature of adenoid cystic carcinoma, is present. Its greatest usefulness appears to be in the detection of distant metastases. CT can not predict invasion of local structures. Contrast material is not useful in improving visualization of fat planes between mediastinal tumor and the aorta. CT underestimates the extent of the tumor in the longitudinal plane. Adenoid cystic carcinoma may grow submucosally without producing a distinct mass.

Pathologically, adenoid cystic carcinoma may infiltrate through the fibrous membrane between adjacent cartilage plates into the peritracheal tissue. Perineural or intraneural infiltration, as well as pericardial, great vessel, or pulmonary hilar involvement may occur. Metastasis to regional lymph nodes may be present in 10% of the cases at the initial diagnosis of tumor. Distant metastases may occur in the lungs, liver, abdomen, lymph nodes or bones.

The treatment of adenoid cystic carcinoma is surgical resection and anastomosis. Criteria for inoperability include excessive longitudinal extent, macroscopic mediastinal nodal metastases, distant metastatic deposits, and direct invasion of contiguous mediastinal structures such as the aorta and the esophagus. When surgery is not indicated, usually because of extensive local disease or metastases, radiation therapy is recommended. Because of the recurrent tendency of this tumor, the eventual outcome of "curative" surgery is difficult to predict.

Five-year and 10-year survivals are excellent, 79% and 57% respectively. However, the long-term outcome is poor due to late local recurrences ( 27% ) and late distant metastatic spread ( 55% ) occurring after a median time interval of 24-180 months after surgery.

References

1. Spizarny DL, Shepard JO, Mcloud TC, et al. CT of adenoid cystic carcinoma of the trachea.
AJR 1986 ; 146 : 1129-1132

2. Li W, Ellerbroek NA, Libshitz HI. Primary malignant tumors of the trachea : a radiologic
and clinical study. Cancer 1990 ; 66 : 894-899

3. Prommegger R, Salzer GM, Long-term results of surgery for adenoid cystic carcinoma of
the trachea and bronchi. Eur J Surg Oncol 1998 ; 24(5) ; 440-444

4. Azar T, Abdul-Karim FW, Tucker HM. Adenoid cystic carcinoma of the trachea.
Laryngoscope 1998 ; 108(9) ; 1297-1300

Keywords

Airway, Malignant tumor,