Figure 1
Thoracic CT - axial, mediastinal window, unenhanced
Thickening of the left lateral wall of the distal trachea, of soft tissue density, with 30 x 13 mm of axial diameters. It causes a 50% luminal stenosis.
A rare case of endotracheal metastasis from lung cancer
SectionChest imaging
Case TypeClinical Cases
AuthorsDaniel Ramos Andrade, Mafalda Magalhães, Luísa Costa Andrade, Luís Curvo Semedo, Filipe Caseiro Alves
Connected authors
60 years, male
Clinical History
A 60 year old asymptomatic male, ex-smoker with emphysema, underwent a follow-up thoracic CT, two years after a left upper lobectomy for a squamous cell carcinoma of the lung (T1N0M0).
Imaging Findings
The two-year follow-up thoracic CT revealed (figure 1, 2, 3 and 4) thickening of the left lateral wall of the distal trachea, of soft tissue density, which caused approximately 50% luminal diameter reduction. There was no cartilage disruption or macroscopic invasion of adjacent structures, although the lesion was in close proximity to the aortic arch and left subclavian artery. There was slight mediastinal shift to the left, as a consequence of the prior upper left lobectomy. Diffuse areas of centrilobular and paraseptal emphysema were noted. There was no evidence of pulmonary metastasis, mediastinal or hilar lymphadenomegaly.
A tracheal metastasis was diagnosed after biopsy.
Laser ablation of the lesion was performed. A chest radiograph was taken, which confirmed the correct placement of the tracheal stent (figure 5).
The patient had already underwent a thoracic CT six months earlier, where inconspicuous findings were noted, interpreted as endoluminal secretions by mistake (figure 6).
A tracheal metastasis was diagnosed after biopsy.
Laser ablation of the lesion was performed. A chest radiograph was taken, which confirmed the correct placement of the tracheal stent (figure 5).
The patient had already underwent a thoracic CT six months earlier, where inconspicuous findings were noted, interpreted as endoluminal secretions by mistake (figure 6).
Discussion
Endotracheal/endobronchial metastases are a relatively common finding in patients with breast, colorectal, and renal carcinomas and melanoma, but, to our knowledge, under 10 cases of endotracheal metastasis from lung cancer have been reported worldwide [1, 2, 3, 4, 5]. The study with the most cases (six) found an overall incidence of tracheal metastasis of only 0.44% in surgically resected non-small cell lung cancer (0.77% in squamous cell carcinomas and 0.18% in adenocarcinomas) [1].
The exact mechanism of endobronchial metastasis remains unknown. The possible mechanism may be the involvement of peribronchial lymphatics with subsequent invasion of the submucosa [6].
The symptoms are the same as those of a primary tumour (dyspnoea, coughing, hemoptysis, stridor and frequent upper airway infections), but the fact that the patient is in a follow up CT protocol makes it more likely to find metastasis before there are clinical manifestations (i.e. before there is significant airway narrowing) [1].
It usually manifests as an endotracheal nodule or eccentric thickening of the tracheal wall on CT, similarly to squamous cell carcinoma and adenoid cystic carcinoma, which are the two most common primary tracheal malignancies.
Distinguishing between an endotracheal tumour and endotracheal phlegm can be a challenging task. The presence of disrupted cartilaginous rings, enhancement after contrast administration, no change with coughing manoeuvre [1], no air inside the "lesion", a non-dependent position, and growth in-between scans all may indicate a real endoluminal tumour.
CT is the standard imaging tool for diagnosis and evaluation of tumour extent.
There are no reliable histologic criteria to differentiate primary from metastatic tumours. Most studies consider endobronchial metastasis to be histopathologically identical to the primary tumour (which was the case with our patient) [1].
There are several options for treating tracheal tumours, some meant for cure (benign and primary tumours) and some only palliative (inoperable tumours or metastasis). In the latter cases, laser therapy with insertion of a tracheobronchial stent to keep the airway open is one of the options (and the one used in our patient, because it was unresectable due to its proximity to the carina).
In conclusion, a high degree of suspicion is warranted when an endotracheal nodule or eccentric thickening of the tracheal wall is found in a patient on CT follow-up for lung cancer.
The exact mechanism of endobronchial metastasis remains unknown. The possible mechanism may be the involvement of peribronchial lymphatics with subsequent invasion of the submucosa [6].
The symptoms are the same as those of a primary tumour (dyspnoea, coughing, hemoptysis, stridor and frequent upper airway infections), but the fact that the patient is in a follow up CT protocol makes it more likely to find metastasis before there are clinical manifestations (i.e. before there is significant airway narrowing) [1].
It usually manifests as an endotracheal nodule or eccentric thickening of the tracheal wall on CT, similarly to squamous cell carcinoma and adenoid cystic carcinoma, which are the two most common primary tracheal malignancies.
Distinguishing between an endotracheal tumour and endotracheal phlegm can be a challenging task. The presence of disrupted cartilaginous rings, enhancement after contrast administration, no change with coughing manoeuvre [1], no air inside the "lesion", a non-dependent position, and growth in-between scans all may indicate a real endoluminal tumour.
CT is the standard imaging tool for diagnosis and evaluation of tumour extent.
There are no reliable histologic criteria to differentiate primary from metastatic tumours. Most studies consider endobronchial metastasis to be histopathologically identical to the primary tumour (which was the case with our patient) [1].
There are several options for treating tracheal tumours, some meant for cure (benign and primary tumours) and some only palliative (inoperable tumours or metastasis). In the latter cases, laser therapy with insertion of a tracheobronchial stent to keep the airway open is one of the options (and the one used in our patient, because it was unresectable due to its proximity to the carina).
In conclusion, a high degree of suspicion is warranted when an endotracheal nodule or eccentric thickening of the tracheal wall is found in a patient on CT follow-up for lung cancer.
Differential Diagnosis List
Endotracheal metastasis of a squamous cell carcinoma of the lung
Endotracheal phlegm
Squamous cell carcinoma
Adenoid cystic carcinoma
Final Diagnosis
Endotracheal metastasis of a squamous cell carcinoma of the lung
References
[1] Chong S, Kim TS, Han J (2006) Tracheal Metastasis of Lung Cancer: CT Findings in Six Patients. AJR Am J Roentgenol Jan;186(1):220-4. (PMID: 16357405)
[2] De S. (2009) Tracheal metastasis of small cell lung cancer. Lung India Oct;26(4):162-4 (PMID: 20532006)
[3] Hyo Chul Youn, Yee Hyung Kim, Young Kyung Lee, Gou Young Kim (2013) Multiple endotracheal and endobronchial metastases after pneumonectomy for a primary lung cancer: A case report. Thoracic Cancer 4(4):453–6
[4] Sakai T, Ikeda T, Kikuchi K, Maruyama M, Fukayama M, Kaseda S. (1986) A case of tracheal metastasis of pulmonary cancer. Nihon Kyobu Geka Gakkai Zasshi Aug;34(8):1178-81 (PMID: 3782945)
[5] Maryjane Liebling, Michael Boyd, Edmundo Rubio, Mahtab Foroozesh (2013) Airway metastasis of small cell lung carcinoma: A rare presentation. Thoracic Cancer 4(4):461–4
[6] Heitmiller RF, Marasco WJ, Hruban RH, Marsh BR (1993) Endobronchial metastasis. J Thorac Cardiovasc Surg Sep;106(3):537-42 (PMID: 8361198)
Case information
| URL: | https://www.eurorad.org/case/11402 |
| DOI: | 10.1594/EURORAD/CASE.11402 |
| ISSN: | 1563-4086 |
Figure 2
Thoracic CT - coronal reformation, mediastinal window, unenhanced
The longitudinal extension of the tumour and its location in the distal trachea - 2 cm from the carina - is better appreciated on this coronal reformat.
Figure 3
Thoracic CT - sagittal reformation, mediastinal window, unenhanced
In this sagittal reformation, the anteroposterior extension of the tumour and the close proximity with the left subclavian artery is better depicted.
Figure 4
Thoracic CT - axial; lung window; unenhanced
At this level the tracheal luminal reduction is more than 50%.
There is mediastinal shift to the left because of prior left upper lobectomy.
Diffuse centrilobular emphysema as a consequence of smoking.
Figure 5
Chest Radiograph, posteroanterior view
Tracheal stent inserted after laser ablation of the lesion.
Mediastinal shift to the left.
Figure 6
6 months earlier Thoracic CT - axial, mediastinal window, unenhanced
Mild thickening of the left lateral wall of the trachea, misinterpreted as endotracheal secretions.
Thoracic CT - axial, mediastinal window, unenhanced
Thickening of the left lateral wall of the distal trachea, of soft tissue density, with 30 x 13 mm of axial diameters. It causes a 50% luminal stenosis.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Thoracic CT - coronal reformation, mediastinal window, unenhanced
The longitudinal extension of the tumour and its location in the distal trachea - 2 cm from the carina - is better appreciated on this coronal reformat.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Thoracic CT - sagittal reformation, mediastinal window, unenhanced
In this sagittal reformation, the anteroposterior extension of the tumour and the close proximity with the left subclavian artery is better depicted.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Thoracic CT - axial; lung window; unenhanced
At this level the tracheal luminal reduction is more than 50%.
There is mediastinal shift to the left because of prior left upper lobectomy.
Diffuse centrilobular emphysema as a consequence of smoking.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Chest Radiograph, posteroanterior view
Tracheal stent inserted after laser ablation of the lesion.
Mediastinal shift to the left.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
6 months earlier Thoracic CT - axial, mediastinal window, unenhanced
Mild thickening of the left lateral wall of the trachea, misinterpreted as endotracheal secretions.
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal
Medical Imaging Department and Faculty of Medicine, University Hospital of Coimbra, Portugal