Adenoid cystic carcinoma of the tracheobronchial tree

Last revised by Yuranga Weerakkody on 25 Apr 2018

Adenoid cystic carcinomas of the tracheobronchial tree are a type of low-grade tracheal tumor. They are considered to be the second most common primary tumor of the trachea.

They are usually first recognized in patients in their 4th and 5th decades. There is no recognized gender predilection.

Symptoms in patients with adenoid cystic carcinoma are usually related to airway obstruction and therefore includes dyspnea, cough, stridor, wheezing, and hemoptysis.

The tumors may be histologically classified into tubular, cribriform, and solid subtypes 6. The tumors are usually low grade but may occasionally undergo high-grade transformation 7.

There is no association with cigarette smoking or with other carcinogens. 9

Adenoid cystic carcinomas usually arise in the lower trachea. Less commonly they are found in the mainstem bronchi (where carcinoid tumors are much more common), lobar bronchi and, rarely, in the segmental bronchi and extrathoracic trachea.

On chest CT, these tumors have a notable tendency toward submucosal extension and typically manifest as:

  • intraluminal mass of soft-tissue attenuation with extension through the tracheal wall, or
  • diffuse or circumferential wall thickening of the trachea, a soft-tissue mass filling the airway, or
  • homogeneous mass encircling the trachea with wall thickening in the transverse and longitudinal planes

The longitudinal extent of the tumors is greater than their axial extent and the tumors usually involve more than 180° of the airway circumference.

They can be variable in shape ranging from polypoid to broad-based. Their margins are also variable and range from smooth to lobulated to irregular. Intratumoral calcification is rare.

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