DOI:10.2214/AJR.04.1711
AJR 2006; 186:220-224
© American Roentgen Ray Society
Tracheal Metastasis of Lung Cancer: CT Findings in Six Patients
Semin Chong1,
Tae Sung Kim1 and
Joungho Han2
1 Department of Radiology and Center for Imaging Science, Samsung Medical
Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-gu,
Seoul 135-710, South Korea.
2 Department of Pathology, Samsung Medical Center, Sungkyunkwan University
School of Medicine, Seoul, South Korea.
Received November 5, 2004;
accepted after revision January 4, 2005.
Supported by grant R11-2002-103 from the Korea Science & Engineering
Foundation.
Address correspondence to T. S. Kim
(tskim.kim{at}samsung.com).
Abstract
OBJECTIVE. Our objective was to assess CT findings of tracheal
metastasis of lung cancer.
CONCLUSION. Tracheal metastasis of primary non-small cell lung
cancer manifested as an endotracheal nodule or eccentric wall thickening of
the trachea, showing contrast enhancement with a predilection for the upper
trachea on CT. During postoperative evaluation of patients with surgically
resected lung cancer, the possibility of tracheal metastasis of lung cancer
should be suggested when an endotracheal nodule or eccentric wall thickening
is present on CT.
Keywords: airway • cancer • CT • lung diseases
Introduction
Tracheal metastasis of primary lung cancer is extremely rare, although
direct tracheal involvement by primary lung cancer is often seen and
classified as T4 lung cancer
[1]. Tracheal metastases from
nonpulmonary malignancies such as breast cancer, colorectal carcinoma, renal
carcinoma, and melanoma have been reported
[2-7].
To our knowledge, however, only one case of tracheal metastasis from primary
lung cancer has been reported in the Japanese-language literature
[8]. To our knowledge, it has
not yet been reported in the English-language literature. We retrospectively
assessed chest CT scans obtained in six patients with histopathologically
proven tracheal metastasis from primary lung cancer.
Materials and Methods
Between November 1995 and September 2004, six patients (all men; age range,
53-68 years; mean age, 61 years) with histopathologically proven tracheal
metastasis after surgical resection of primary lung cancer were identified
from the file archives of the department of pathology at our institute.
Approval from the institutional review board was not needed for review of
pathologic reports and radiologic images in our institute. We retrospectively
reviewed the patients' clinical, CT, and histopathologic findings.
Clinical features and histologic subtypes of the previously resected lung
cancer in the patients are summarized in
Table 1. The location of the
initial primary lung cancers was the right lower lobe (n = 3), left
upper lobe (n = 2), or left lower lobe (n =1). The cell type
of the primary lung cancers was squamous cell carcinoma (n = 5) or
adenocarcinoma (n = 1). All patients underwent lobectomy (n
=4) or pneumonectomy (n = 2) for primary lung cancer, and their
pathologic staging was IA (n = 1), IB (n = 2), IIB
(n = 1), or IIIA (n = 2). After surgery, all six patients
were followed up with a chest CT scan at 3-6 months for early detection of
possible tumor recurrence or pulmonary metastasis. At the time of diagnosis of
tracheal metastasis, all patients were asymptomatic and had no extrathoracic
metastatic lesions.
View this table:
[in this window]
[in a new window]
|
TABLE 1: Clinical Features and CT Findings of Six Patients with Tracheal
Metastasis of Surgically Resected Non–Small Cell Lung Cancer
|
|
Nonenhanced and contrast-enhanced helical chest CT images were obtained in
all patients using a helical CT scanner (HiSpeed Advantage, GE Healthcare).
The parameters of the helical chest CT examination were a 5-mm collimation and
a 10-mm/sec table feed. Contrast-enhanced chest CT scans were obtained after
injection of 30 g of iodinated contrast medium (100 mL of iopamidol [Iopamiron
300, Bracco]) at a rate of 3 mL/sec with a power injector (OP 100,
Medrad).
Chest CT scans were analyzed retrospectively and jointly by two
radiologists with 7 and 2 years of experience, respectively, in chest
radiology. The decisions on the CT findings were reached by consensus. Chest
CT scans were assessed specifically for the location and pattern of tracheal
abnormalities, degree of contrast enhancement, and presence or absence of
disruption of the cartilaginous rings and mediastinal or hilar
lymphadenopathy. We classified the location of tracheal abnormalities into the
upper or lower trachea from a horizontal line drawn tangential to the upper
margin of the aortic arch; right or left side of the tracheal wall; and
anterior, posterior, or lateral portion based on the cross-sectional scan. We
classified the pattern of tracheal abnormalities into an endotracheal nodule
or eccentric wall thickening with endo- and exophytic tumor growth. We
measured the longest diameter of the endotracheal nodule or the maximum
thickness of tracheal wall thickening. Contrast enhancement was regarded as
significant when a net enhancement of more than 10 H between pre- and
postcontrast images at the same level was present.
All six patients underwent bronchoscopic biopsy for the tracheal lesion.
One of them underwent segmental resection and anastomosis of the trachea. The
histopathologic findings of the specimens obtained from bronchoscopic biopsy
or surgical resection were evaluated by a pathologist with 9 years of
experience. We defined tracheal metastasis from primary lung cancer as
tracheal lesions histopathologically identical to the previous primary lung
cancer.
We calculated the recurrence interval, which was defined as the time
interval from the resection of the primary lung cancer to the detection of the
tracheal abnormality on follow-up CT, and assessed the overall incidence of
tracheal metastasis in surgically resected primary lung cancers. We also
reviewed patients' treatment and clinical outcome.
Results
CT findings of tracheal metastasis in the six patients are summarized in
Table 1. All six patients
showed an endotracheal nodule (n = 4) (Figs.
1A,
1B, and
2A) or eccentric tracheal wall
thickening with endo- and exophytic tumor growth (n = 2)
(Fig. 3A) on CT. The location
of the endotracheal nodule or eccentric wall thickening was the upper
(n =4) or lower (n = 2) trachea based on the upper margin of
the aortic arch. The tracheal lesion was located in the right (n =
1), midline (n = 1), or left (n =4) side of the trachea,
which was the anterolateral (n =3), anterior (n = 1), or
posterolateral (n = 2) portion of the trachea. The longest diameters
of the endotracheal nodule or the maximum thickness of eccentric wall
thickening were 6-27 mm (mean, 14.3 ± 7.5 [SD] mm). We assessed the
degree of contrast enhancement in five patients, which showed 20-30 H (mean,
24.6 ± 4.6 H) of net enhancement. In the remaining patient (patient 4),
we could not obtain the value of net enhancement because a 6-mm endotracheal
nodule was not covered in a precontrast thin-section (1-mm collimation) scan
because of a scanning gap. Partial disruption of a cartilaginous ring by the
tracheal tumor was noted in five patients. Mediastinal (n = 3) or
hilar (n = 1) lymph nodes (7 or 8 mm) were seen in three patients.
Among them, a 7-mm right upper paratracheal lymph node (patient 3) was
histopathologically proven to be a metastatic lymph node from squamous cell
carcinoma at surgery (tracheal resection and anastomosis). One patient
(patient 4) had a simultaneous pulmonary metastasis with an 11-mm nodule in
the left lower lobe.
View larger version (61K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1A —53-year-old man who had undergone right middle and lower
lobectomy for squamous cell carcinoma 52 months earlier (patient 3 in
Table 1). Chest CT scan shows
10-mm endotracheal nodule (arrow) in right lower posterolateral
portion of trachea.
|
|
View larger version (116K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1B —53-year-old man who had undergone right middle and lower
lobectomy for squamous cell carcinoma 52 months earlier (patient 3 in
Table 1). Photomicrograph of
transaxial section of gross specimen obtained from tracheal resection and
anastomosis shows endotracheal polypoid nodule (arrows) with
transmural growth. (H and E, x1)
|
|
View larger version (111K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2A —60-year-old man who had undergone left upper lobectomy for
adenocarcinoma 26 months earlier (patient 1). Chest CT scan shows 13-mm
endotracheal nodule (arrow) in left upper posterolateral portion of
trachea.
|
|
View larger version (75K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3A —68-year-old man who had undergone left upper lobectomy for
squamous cell carcinoma 17 months earlier (patient 2). Chest CT scan shows
eccentric thickening (arrow) of anterior midline portion of tracheal
wall.
|
|
On histopathologic examination of tracheal biopsy specimens obtained from
all patients, the cell type of the tracheal lesion was squamous cell carcinoma
(n = 5) (Figs. 1C and
3B) or adenocarcinoma
(n = 1) (Fig. 2B). All
tracheal tumor cells were identical to the previously resected primary lung
cancers and were seen in the submucosal layer. As described above, one of four
lymph nodes was surgically resected and proved to be a metastasis from the
previously resected squamous cell carcinoma.
View larger version (163K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1C —53-year-old man who had undergone right middle and lower
lobectomy for squamous cell carcinoma 52 months earlier (patient 3 in
Table 1). Photomicrograph of
pathologic specimen reveals well-differentiated squamous cell carcinoma
showing densely eosinophilic foci (arrows) corresponding to keratin
pearl formation. (H and E, x200)
|
|
View larger version (161K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3B —68-year-old man who had undergone left upper lobectomy for
squamous cell carcinoma 17 months earlier (patient 2). Photomicrograph of
histopathologic specimen obtained from bronchoscopic biopsy shows nest of
squamous cell carcinoma (arrowheads) in submucosal layer. Note normal
overlying respiratory mucosa (arrows). (H and E, x100)
|
|
View larger version (151K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2B —60-year-old man who had undergone left upper lobectomy for
adenocarcinoma 26 months earlier (patient 1). Photomicrograph of
histopathologic specimen obtained from bronchoscopic biopsy shows
adenocarcinoma forming acini (arrow) and micropapilla
(arrowheads). (H and E, x200)
|
|
In our series, the overall incidence of tracheal metastasis was 0.44%
(6/1,372) in the surgically resected non-small cell lung cancers during the
same period in our institute of 8 years 10 months: 0.77% (5/647) in squamous
cell carcinomas and 0.18% (1/552) in adenocarcinomas. The recurrence interval
was 8-52 months (mean, 25.8 ± 17.4 months) after their initial
operation.
Shortly after the diagnosis of newly developed tracheal metastasis, four
patients underwent radiation therapy and one patient was treated with
chemotherapy. The remaining patient (Figs.
1A,
1B, and
1C) underwent tracheal
segmental resection and anastomosis. All patients showed complete remission of
the tracheal metastasis and, to date or as of the last follow-up examination,
have not had a known recurrence. All patients were alive for the 17- to
68-month follow-up period (mean, 35 ± 21 months) after the previous
surgical resection of the primary lung cancer. However, five of six patients
showed newly developed metastatic lesions (metastatic mediastinal lymph nodes,
stump recurrence, or lung-to-lung metastasis) on follow-up CT scans. After
subsequent radiation therapy or chemotherapy, they have been in partial
response (n = 3) or progressive disease (n = 2)
(Table 1).
Discussion
To our knowledge, the incidence of endotracheal or endobronchial metastasis
of primary lung cancer has not been reported in the literature. However, the
incidence of endotracheal or endobronchial metastasis of nonpulmonary
malignancies is known to vary, ranging from approximately 2% to 50%, according
to how they are defined
[9-14].
In our study, the overall incidence of tracheal metastasis was 0.44% (6/1,372)
in surgically resected non-small cell lung cancer (0.77% in squamous cell
carcinomas and 0.18% in adenocarcinomas), and the incidence of tracheal
metastasis was lower in primary lung cancers than in nonpulmonary
malignancies.
The symptoms associated with endotracheal and endobronchial metastases
regardless of its primary site are similar to those associated with primary
endotracheal and endobronchial tumors. Hemoptysis with coughing is the most
common symptom, with an incidence of 41-62% reported
[9,
15]. In our study, all
patients with tracheal metastasis were free of symptoms despite the
endotracheal nodule or eccentric wall thickening shown on CT. The small
endotracheal nodule or mild wall thickening did not result in significant
airway narrowing in our series. The periodic postoperative follow-up CT
examinations that were performed may have detected the tracheal metastasis at
a subclinical stage—that is, before the onset of clinical symptoms and
signs.
In primary tracheal tumors, the most frequent site is the lower one third
of the trachea [16]. However,
tracheal metastasis of non-small cell lung cancer in our series showed a
predilection for the upper trachea (n = 4) in location, although the
study population was small (n = 6). In our series, the site of
tracheal metastasis was ipsilateral to that of the primary tumor in three
patients, contralateral in two patients, and midline in one. Therefore, there
seemed to be no correlation in laterality between the location of the primary
tumor and the site of tracheal metastasis.
In a clinicopathologic study of endotracheal and endobronchial metastases,
Kiryu et al. [17] proposed
four types of developmental modes of endotracheal and endobronchial metastases
in a morphologic way: type 1, direct metastasis to the bronchus; type 2,
bronchial invasion by a parenchymal lesion; type 3, bronchial invasion by
mediastinal or hilar lymph node metastasis; and type 4, a peripheral lesion
extending along the proximal bronchus. We suggest that the developmental mode
of endotracheal metastasis in our series corresponded to type 1 metastasis
(direct metastasis). In a study of endobronchial metastasis, Heitmiller et al.
[14] proposed that the
metastatic tumor migrated along the lymphatics with subsequent egress into the
submucosal space. In our study, all tracheal tumor cells involved the
submucosal layer, and some tracheal tumor cells were found within the
submucosal lymphatic vessels presenting as tumor emboli (patient 1). These
histologic findings support the assertion that tracheal tumor cells may
originate from the primary site via submucosal lymphatic or blood vessels
rather than from carcinoma in situ by field cancerization theory
[18], which was proposed to
explain the development of multiple primary tumors and locally recurrent
cancer. According to the theory, the persistence of abnormal tissue after
surgery (a preneoplastic field with genetically altered cells) may explain the
development of secondary primary tumors by epithelial malignant transformation
in the normal mucosa [18]. In
our cases, however, tumor cells were located only in the submucosal layer
without invasion of mucosal epithelium. Therefore, our cases should be
considered tracheal metastasis rather than a secondary primary tracheal
tumor.
Endotracheal and endobronchial metastases from nonpulmonary malignancies
have been reported to progress relatively slowly
[10]. In endotracheal and
endobronchial metastases from nonpulmonary malignancies, the reported median
recurrence intervals were 50.4-65.3 months
[10,
11,
17]. In our study, the mean
recurrence interval was 25.8 months. We suggest that our shorter mean
recurrence interval may have resulted from early detection of subclinical
tracheal metastasis during periodic postoperative follow-up examinations.
When an endotracheal nodule is present on a postoperative CT scan, an
endotracheal tumor needs to be distinguished from an endotracheal phlegm
termed "mucoid pseudotumor," which can be confirmed by its
disappearance on a subsequent study or upward migration of the mucous plug
after an episode of vigorous coughing
[19]. In the present study, we
found frequent disruption of the cartilaginous rings (n =5) and
contrast enhancement (n = 5) of the tracheal lesions. To distinguish
an endotracheal tumor from an endotracheal phlegm, therefore, we suggest an
evaluation of the imaging criteria— that is, the presence or absence of
disrupted cartilaginous rings, high-resolution CT after contrast enhancement,
and possible CT maneuvers (repeated or coughing after CT).
Our study has some limitations. The major limitation is that the sample
size was small because of the very low incidence of tracheal metastasis from
primary lung cancer. Second, the bronchoscopic biopsy specimens may not be
satisfactory to differentiate between primary and secondary tracheal
malignancies. Salud et al.
[11] suggested that there is
no absolute histopathologic criteria to differentiate between primary and
secondary tumors, although knowledge of the clinical situation and results
from immunohistochemical techniques can be useful. Therefore, most study
groups, including our study group, have defined endotracheal or endobronchial
metastasis as the lesions histopathologically identical to the primary tumors
previously documented
[17].
In conclusion, tracheal metastasis of non-small cell lung cancer manifested
as an endotracheal nodule or eccentric thickening of the tracheal wall,
showing contrast enhancement with a predilection for the upper trachea on CT.
During postoperative evaluation of patients with surgically resected lung
cancer, the possibility of tracheal metastasis of lung cancer should be
suggested when an endotracheal nodule or eccentric thickening of the tracheal
wall is seen on CT.
References
- Kameyama K, Huang CL, Liu D, et al. Problems related to TNM
staging: patients with stage III non-small cell lung cancer. J
Thorac Cardiovasc Surg 2002;124
: 503-510[Abstract/Free Full Text]
- DeBeer RA, Garcia RL, Alexander SC. Endobronchial metastasis from
cancer of the breast. Chest 1978;73
: 94-96[Abstract/Free Full Text]
- Albertini RE, Ekberg NL. Endobronchial metastasis in breast cancer.
Thorax 1980; 35:435
-440[Abstract]
- Watanabe S, Oda M, Ohta Y, Watanabe G. Endotracheal metastasis of
rectal cancer. Eur J Cardiothorac Surg2002; 21:924[Free Full Text]
- MacMahon H, O'Connell DJ, Cimochowski GE. Pedunculated endotracheal
metastasis. AJR 1978;131
: 713-714[Medline]
- Koyi H, Branden E. Intratracheal metastasis from malignant
melanoma. J Eur Acad Dermatol Venereol2000; 14:407
-408[Medline]
- Fraser RS, Muller NL, Colman N, Pare PD. Diagnosis of
diseases of the chest, 4th ed. Philadelphia, PA: WB Saunders,1999
: 1381-1417
- Sakai T, Ikeda T, Kikuchi K, Maruyama M, Fukayama M, Kaseda S. A
case of tracheal metastasis of pulmonary cancer [in Japanese].
Nippon Kyobu Geka Gakkai Zasshi 1986;34
: 1178-1181[Medline]
- Braman SS, Whitcomb ME. Endobronchial metastasis. Arch
Intern Med 1975; 135:543
-547[Abstract]
- Baumgartner WA, Mark JB. Metastatic malignancies from distant sites
to the tracheobronchial tree. J Thorac Cardiovasc Surg1980; 79:499
-503[Medline]
- Salud A, Porcel JM, Rovirosa A, Bellmunt J. Endobronchial
metastatic disease: analysis of 32 cases. J Surg Oncol1996; 62:249
-252[CrossRef][Medline]
- Katsimbri PP, Bamias AT, Froudarakis ME, Peponis IA,
Constantopoulos SH, Pavlidis NA. Endobronchial metastases secondary to solid
tumors: report of eight cases and review of the literature. Lung
Cancer 2000; 28:163
-170[CrossRef][Medline]
- King TE Jr, Neff TA, Ziporin P. Endobronchial metastasis from the
uterine cervix: presentation as primary lung abscess.
JAMA 1979; 242:1651
-1652[CrossRef][Medline]
- Heitmiller RF, Marasco WJ, Hruban RH, Marsh BR. Endobronchial
metastasis. J Thorac Cardiovasc Surg1993; 106:537
-542[Abstract]
- Fitzgerald RH Jr. Endobronchial metastases. South Med
J 1977; 70:440
-441[Medline]
- Weber AL, Grillo HC. Tracheal tumors: a radiological, clinical, and
pathological evaluation of 84 cases. Radiol Clin North
Am 1978; 16:227
-246[Medline]
- Kiryu T, Hoshi H, Matsui E, et al. Endotracheal/endobronchial
metastases: clinicopathologic study with special reference to developmental
modes. Chest 2001;119
: 768-775[Abstract/Free Full Text]
- Braakhuis BJ, Tabor MP, Kummer JA, Leemans CR, Brakenhoff RH. A
genetic explanation of Slaughter's concept of field cancerization: evidence
and clinical implications. Cancer Res2003; 63:1727
-1730[Abstract/Free Full Text]
- Fraser RS, Muller NL, Colman N, Pare PD. Diagnosis of
diseases of the chest, 4th ed. Philadelphia, PA: WB Saunders,1999
: 1251-1261
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
Top
Abstract
Introduction
