- 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.
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