Tracheal Tumors Workup

Updated: Sep 23, 2019
  • Author: Brian J Daley, MD, MBA, FACS, FCCP, CNSC; Chief Editor: Mary C Mancini, MD, PhD, MMM  more...
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Workup

Approach Considerations

Tracheal lesions may be evaluated by means of bronchoscopy or radiographic imaging (see below).

Besides allowing biopsy for tissue diagnosis, newer modalities such as lasers can be applied endoscopically.

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Imaging Studies

The initial study invariably is a plain chest radiograph, which usually shows normal lung fields. [3] This result can delay the diagnosis of a tracheal tumor. Standard chest radiography is insensitive in the detection of tracheal neoplasms, and fewer than 50% of tracheal tumors are diagnosed by using this modality. [3] Diagnostic clues to the presence of a tracheal tumor on chest radiographs include the following:

  • Tracheal narrowing
  • Postobstructive atelectasis or pneumonia
  • Abnormal calcification

Planar tomography is much more sensitive in displaying tracheal tumors, but computed tomography (CT) is currently the imaging technique of choice. [3] Planar tomography was used before CT became the standard technique, primarily for better localization of lesions.

Conventional CT protocols may miss small lesions. CT is best performed by using a spiral (helical) scanner, which allows precise volumetric acquisition and multiplanar image display. Spiral CT can also help differentiate mucosal from submucosal masses and reveal the extent of submucosal spread. [3]

Magnetic resonance imaging (MRI) may be applied to tracheal tumors for better evaluation of extension into tissue planes and vascular anatomy.

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Bronchoscopy

Bronchoscopy is part of the evaluation for most pneumonic processes. Its role is to help identify obstructions, whether intrinsic to the tracheal/bronchial lumen or extrinsic and causing compression. Bronchoscopy should be performed under optimal conditions because the risk of acute airway compromise is high.

Bronchoscopy remains the criterion standard because it provides definitive evaluation of the airway, allows assessment of gives anatomic considerations, and is capable of obtaining tissue samples for diagnosis.

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Histologic Findings

Malignant tumors

Malignant bronchial gland tumors arise from salivary glands with the trachea.

Adenoid cystic carcinoma (ACC) is seen primarily in individuals aged 13-79 years and is evenly distributed between males and females. It grows so slowly in many patients that it appears to be benign in behavior, even after metastases have occurred to the lungs. Some lesions are highly malignant and spread to pleura and lungs before they are discovered. Remote metastasis occurs most often to lung and bone. This cell type constitutes 90% of tumors. Mucoepidermoid carcinoma, mucinous cystadenoma, and pleomorphic adenoma have all been reported in decreasing frequency.

Bronchial carcinoids are derived from the neuroendocrine cell line, as are other amine precursor uptake and decarboxylation cell tumors. They are part of a spectrum of tumors derived from the same cell line, which ranges from typical carcinoids (which usually follow a benign course) to the more aggressive atypical carcinoids and the highly malignant small cell lung cancer (SCLC). The cells are capable of secreting active peptide hormones, as do other carcinoids. This is rarely of clinical significance, because the carcinoid syndrome is quite rare with bronchial or tracheal tumors. Thus, most tumors present with obstructive-type symptoms.

In a newer classification, carcinoid tumors are part of a larger group of lesions referred to as neuroendocrine tumors of the lung. These neuroendocrine tumors include histologically low-grade tumors; typical and atypical carcinoids; and histologically high-grade lesions, large cell neuroendocrine carcinoma, paraganglionoma, and small cell carcinoma. In addition, squamous cell carcinoma (SCC), adenocarcinoma, and large cell carcinoma may exhibit neuroendocrine features. This classification is likely applicable to lesions occurring in the trachea and the lung.

SCC may present as a well-localized lesion of exophytic type or as an ulcerating lesion. Multiple lesions with interspersed normal trachea and superficial infiltrating carcinoma, which may extend over the whole length of the trachea, also occur. Approximately one third of the patients have mediastinal or pulmonary metastases at the time of initial diagnosis. The distribution of SCC of the trachea is comparable to that of squamous bronchogenic carcinoma with respect to age (50-70 years) and sex (male-to-female ratio, 3:1).

Metastatic tumors have also been reported.

Benign tumors

Squamous papillomas are the most common of the benign tumors and are associated with human papillomavirus types 6 and 11. They frequently occur in the larynx and present as vocal changes. They appear as irregular, papillary, or villous processes covered by thick squamous epithelium blending into the normal respiratory epithelium. They may represent a premalignant type of lesion. Simple extirpation results in almost universal recurrence, and radical resection is advocated for complete removal. Modern technological modalities for control are being applied to avoid radical resection.

Cartilaginous tumors are next in frequency. They appear as gray-to-white firm masses with focal gritty areas secondary to calcification and are composed of cartilage and bone cells with an intact overlying mucosa. Cartilaginous tumors generally occur in the fifth and sixth decades of life and carry a potential for sarcomatous change. Complete resection is indicated.

Other tumors

Other tracheal tumors occur but are exceedingly rare. These include the following:

Thyroid tissue may be present ectopically within the trachea. This ectopic tissue also has a potential for malignant change and should be excised.

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Staging

No standard staging classification for primary tracheal tumors has been widely accepted in the literature. Historically, all tracheal tumors were defined as stage IV lung cancer on the basis of American Joint Committee on Cancer (AJCC) staging criteria, which derived from the tumor-node-metastasis (TNM) classification. In 2004, however, Bhattacharyya delineated a staging system for primary tracheal tumors that showed a distinct survival advantage in stage I and stage II disease. [8] This system is as follows:

  • TX: Unknown or unable to be assessed
  • T1: Primary tumor confined to trachea, < 2 cm
  • T2: Primary tumor confined to trachea, >2 cm
  • T3: Spread outside the trachea but not to adjacent organs or structures
  • T4: Spread to adjacent organs or structures
  • N0: No evidence of regional nodal disease
  • N1: Positive regional nodal disease
  • NX: Unknown or unable to be assessed

In terms of the TNM classification, stage I disease is defined as T1N0, stage II is T2N0, stage III is T2N0, and stage IV is T4N0 or TanyN1 or any distant metastasis. Stage for stage, ACC has the better prognosis, with reported 5-year survival rates of 66-100% and 10-year survival rates of 51-62%. SCC has a reported 5-year survival rate of 10% and a 10-year survival rate of 35-40%. Bhattacharyya's paper demonstrated a clear survival advantage for stage I and stage II disease, citing 5-year survival rates of 70-80%. [8] T4 disease or any nodal involvement confers a dismal prognosis, with 5-year survival rates of 15% or less.

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