Endobronchial metastasis from slow-growing lung cancer: A rare case report and review of the literature
Article Outline
- Summary
- Introduction
- Case report
- Discussion
- Conflict of interest statement
- Aknowledgements
- References
- Copyright
Summary
The case of a 36-year-old man with slow-growing lung adenosquamous cell carcinoma and an endobronchial metastasis is reported. Several nodules had been found on a chest X-ray taken 1 year earlier. The same nodules, with no signs of significant progression, were observed during the present admission. A chest computed tomography (CT) image revealed a polypoid lesion in the right intermediate bronchus. Microscopic examination of the polypoid tumor suggested some malignant suspected neoplasm. Therefore, a right intermediate bronchus and right middle and lower lobe lung resection were performed. Histology of the lung nodules revealed an adenosquamous cell carcinoma that closely resembled the endobronchial polypoid tumor. We concluded that the endobronchial tumor was a metastasis of slow-growing lung adenosquamous cell carcinoma. The literature was also reviewed for Japanese patients with endobronchial metastasis who had been treated between 1984 and 2007. Endobronchial metastases originated from 17 different diagnoses of primary malignancies in 90 patients.
Keywords: Endobronchial tumor, Endotracheal metastasis, Pulmonary metastasis, Lung cancer, Thoracic surgery
Abbreviations: CXR, chest X-ray, CT, computed tomography
Introduction
Metastases are usually scattered in the lung parenchyma or pleura, and bronchial invasion as a result of mediastinal or hilar lymph node metastasis is sometimes seen.1, 2 Endobronchial metastases, in which the bronchial epithelium is directly involved, are rare. Endobronchial metastases from lung cancer usually develop at least several months after the resection of the primary site.3, 4 In contrast, the endobronchial metastasis was congruent with the primary tumor in the present case. We hereby report our experience of a rare, slow-growing adenosquamous lung cancer that was found as a result of a direct endobronchial metastasis without any symptoms. We also reviewed the Japanese and English medical literature, emphasizing reports on Japanese patients, for reports of endobronchial metastasis between 1984 and 2007.
Case report
A 36-year-old Japanese man who had had some nodular shadows in his right lower lung field pointed out on a chest X-ray (CXR) came to our hospital. The nodules had been found during a health examination performed 1 year earlier, but the patient had ignored the findings. He did not have any complaints (i.e. coughing, sputum, blood-tinged phlegm, fever, or body weight loss) and did not have a history of smoking or exposure to asbestos or radiation. No wheezing in the bronchus area was heard on auscultation. A CXR revealed three nodular shadows in the right lower lung field (Figure 1(A)). No significant progression in the number or size of the co-existing nodular shadows was seen when compared with the CXR results obtained 1 year earlier. A computed tomography (CT) image of the chest revealed four nodules from 1 to 2
cm in diameter in the S5, S8, S9, and S10 regions (Figure 1(B)) and a 13mm polypoid lesion in the right intermediate bronchus (Figure 1(C)); no signs of mediastinal lymph node involvement were seen. Laboratory findings showed no elevation in LDH and normal levels of tumor markers. A biopsy of the polypoid lesion was performed via a bronchoscope (Figure 2). Microscopic examination of the specimen suggested some malignant suspected neoplasm. We did not insert the bronchoscope into the distal bronchus to avoid passing the scope over the polypoid tumor. The nodules in the right lung were thought to be benign tumors or inflammatory (change) s, when we did the bronchoscopic examination.
Figure 1.
Chest X-ray and chest computed tomography (CT) image. A chest X-ray (CXR) shows (A) nodular shadows in the right lower lung field (arrows). The number and size of these nodular shadows were similar to CXR findings obtained 1 year earlier. Chest CT images show (B) a nodular shadow with pleural indentation in the right S10 (arrow), and (C) a polypoid lesion 13
mm in diameter in the right intermediate bronchus (arrow).
Figure 2.
Bronchoscopic examination. A polypoid tumor with a smooth surface and a clear margin was seen in the right intermediate bronchus (arrow heads).
The patient was admitted to our hospital, and a surgery to resect the endobronchial neoplasm was performed. During the thoracic surgery, the pathological appearance of the nodules in the right S8 and S10 regions were thought to resemble that of adenosquamous cell carcinoma (Figure 3), and its appearance closely resembled the specimen obtained from the right intermediate bronchial polypoid tumor via the bronchoscope before surgery. As a result, a right intermediate bronchus resection including the right middle and lower lobe and lymph nodes was performed. After the surgery, the tissue obtained from the remainder of the polypoid tumor in the right intermediate bronchus was examined; the biopsied specimen of the polypoid tumor was also reexamined. These pathological examinations revealed that the endobronchial polypoid tumor was a submucosal tumor with pathological characteristics similar to those of the tissues taken from the lung nodules: adenosquamous cell carcinoma. The final diagnosis was very slow-growing primary lung adenosquamous cell carcinoma of the right S10 with multiple metastases to the right middle and lower lobes and the right intermediate bronchus. The patient was informed of the pathological results, and adjuvant chemotherapy was recommended. However, the patient decided not to undergo chemotherapy because he felt he was in good health. He has not had any recurrence or metastases for 3 years since the resection.
Figure 3.
Pathological features of lung nodules. The pathologic findings of the resected tumor in the right S10 region showed both papillary adenocarcinoma (left) and squamous cell carcinoma (right) compartments.
Discussion
In this report, we have described a patient who presented with an endobronchial metastatic tumor originating from a slow-growing lung adenosquamous cell carcinoma. The spread of lung carcinoma to the bronchus is uncommon. Only nodular shadows were apparent on a CXR, and the endobronchial tumor was unexpectedly found when a chest CT image was taken. On the CT image, the pleural indentation of the lung nodules suggested the possibility of a malignant neoplasm of the lung, but we thought that the nodules were either benign tumors or inflammatory changes (i.e. pulmonary cryptococcosis), because (1) the number of those nodules did not increased over the course of 1 year, (2) they were found within only the right lung, and (3) none of the tumor markers were elevated. During surgery, a quick microscopic examination revealed that the resected lung nodules were adenosquamous cell carcinoma, and the pathological findings of the endobronchial polypoid tumor obtained during a previous bronchoscopic examination were found to be similar. This case was thought to be a primary lung cancer with metastasis. We, however, performed a right intermediate bronchus resection that included the right middle and lower lobe in this patient, because this seemed to be a slow-growing, low-grade malignancy.
The frequencies of endobronchial metastasis vary according to its definition, ranging from 2% to 50% of pulmonary metastases from extrathoracic neoplasms.5, 6, 7 In previous reports, however, “endobronchial metastases” included not only direct metastasis to the bronchus, but also bronchial invasion by a parenchymal lesion and mediastinal or hilar lymph node metastasis as well as the extension of a peripheral lesion along the proximal bronchus. The pathological mechanisms for these lesions differ from one another. Kiryu et al.2 proposed four developmental conditions for “endobronchial metastasis” and defined direct metastasis to the bronchus as “endobronchial metastasis”. Endobronchial metastases directly involving the bronchial epithelium are rare, with reported frequencies ranging from 2% to 11% of pulmonary metastases from extrathoracic neoplasms.5, 6, 8, 9 Metastatic endobronchial carcinoma usually originates from the breast, kidney, and colon.1, 2, 4, 11, 12 We reviewed the Japanese and English medical literature regarding Japanese patients with endobronchial metastasis by searching the MEDLINE and JMEDPlus databases for articles written between 1984 and 2007. Only articles describing direct endobronchial metastasis were reviewed, and 90 patients with pulmonary and extrapulmonary malignancies were identified. The most frequent primary diagnoses were cancer of the lung (18 cases), colon and rectum (17 cases), breast (13 cases), and kidney (12 cases). More rarely reported primary tumors included cancers in the thyroid gland, prostate, uterine cervix, malignant melanoma, stomach, osteosarcoma, uterine corpus, pancreas, head and neck, urinary bladder, liver, plasmacytoma, and unknown origin (Table 1). Since the first case of a direct endobronchial metastasis from the lung reported by Fujimura et al.10 in 1984, only 18 lung cancer cases with direct endobronchial metastasis have been reported in Japan.
Table 1. Primary tumors with related endobronchial metastasis in Japan (1984–2007).
| Primary tumor | n |
|---|---|
| Lung | 18 |
| Colorectal | 17 |
| Breast | 13 |
| Kidney | 12 |
| Thyroid | 4 |
| Prostate | 4 |
| Uterine cervix | 4 |
| Malignant melanoma | 3 |
| Stomach | 3 |
| Osteosarcoma | 2 |
| Uterine corpus | 2 |
| Pancreas | 2 |
| Head and neck | 2 |
| Urinary bladder | 1 |
| Liver | 1 |
| Plasmacytoma | 1 |
| Unknown | 1 |
| Total | 90 |
Four endobronchial metastatic routes are thought to exist: (1) tumor emboli lodge in smaller pulmonary arteries and spread through the vessel walls to the perivascular lymphatics. Tumor cells may subsequently spread centripetally in the peribronchial lymphatics and give rise to a discrete deposit of tumor growth beneath the respiratory epithelium. (2) Hilar lymph nodes promote retrograde centrifugal spreading of the tumor cells through the peribronchial lymphatics. (3) Tumor cells reach the bronchial wall by way of the bronchial arteries, since individual tumor cells can pass through the pulmonary arteries and capillaries and into the aorta. (4) Metastatic deposits reach the bronchi through the aspiration of tumor cells from pharyngeal, tracheal, or other bronchial lesions.11 In the present case, no tumor cells were found in the peribronchial lymphatics, hilar lymph nodes, or mediastinal lymph nodes. The metastatic polypoid tumor was covered with normal mucosa. Bronchogenic dissemination could not explain the metastatic submucosal polypoid tumor in this case. The distance between the primary site and the endobronchial polypoid tumor was also quite far. The pathological results further denied the possibility of submucosal direct invasion to the bronchus. In conclusion, the largest nodule, located in S10, was thought to be the primary site of the lung cancer in this patient, with the lung metastases in the right middle and lower lung and the endobronchial metastasis in the right intermediate bronchus arising via dissemination through the bronchial arteries.
Most cases of endobronchial metastases occurred as relapsed malignancies.3, 4, 12, 13, 14 We also believe that this is the first case of a primary lung cancer with a congruent endobronchial metastasis.
Conflict of interest statement
None declared.
Aknowledgements
The authors wish to acknowledge the valuable comments of Dr. Hidenori Hara, PhD, regarding the histology.
References
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PII: S1755-0017(08)00009-2
doi:10.1016/j.rmedc.2008.01.002
© 2008 Elsevier Ltd. All rights reserved.
