Photo Essay: Patterns of Pulmonary and Thoracic Metastatic Disease
The lungs are a common site of metastatic disease (Table). Because the entire cardiac output flows through the lungs, the risk of hematogenous metastases is very high.
Excluding primary lung cancers, which can metastasize to either lung, the most common metastases that involve the lung parenchyma are breast cancer; GI tract tumors; kidney cancer; melanoma; sarcoma; lymphoma and leukemia; germ cell tumors; and, rarely, ovarian cancer.l In most cases, management of lung metastases relies on systemic treatment of the primary malignancy.
Chest radiography is usually the first study performed to detect pulmonary metastases. Metastases may also be unexpectedly identified during a routine radiographic examination of the chest.
CT scans are useful because they have a higher resolution than plain radiographs; they can depict more nodules and nodules of smaller size. High-resolution CT is the modality of choice for demonstrating the presence and extent of lymphangitic carcinomatosis. Bronchoscopy and biopsy or transthoracic biopsy andneedle aspiration may help determine the nature of pulmonary nodules.
Here we present diagnostic images that show the typical patterns of pulmonary metastatic disease, including parenchymal nodules, lymphangitic carcinomatosis, and endobronchial obstructions. We also show examples of pleural and pericardial effusion, mediastinal lymphadenopathy, and bone and cutaneous metastases.
REFERENCE:
1. Libshitz HI, North LB. Pulmonary metastases. Radiol Clin North Am. 1982;20:437-451.
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Lymphangitic Carcinomatosis
This chest film of a patient with pancreatic cancer shows reticulo-nodular infiltrates and prominent hilar lymph nodes. The infiltrates suggest lymphangitic carcinomatosis, which is much more visible on high-resolution CT scanning of the chest. There is also a nodule in the right middle lobe.
Fewer than 10% of lung metastases have a lymphangitic pattern.1 Although any neoplasm can cause lymphangitic spread, the most common lymphangitic tumors originate in the lungs, breast, stomach, pancreas, or prostate. The typical radiographic pattern consists of thickened interlobular septa (5 to 10 mm or smaller) and bronchovascular markings of irregular shape.1 Most patients become severely dyspneic and die within a few months.
REFERENCE:
1. Khan AN. Lymphangitic carcinomatosis. Available at: http://www.emedicine.com/radio/topic416.htm. Accessed March 21, 2005.
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Metastatic Skin Lesion
This slightly raised, round, indurated, erythematous lesion on the back of a man with multiple myeloma contained extensive subcutaneous deposits suggestive of plasmacytomas along with chest wall involvement. The chest wall may also be involved in patients with lymphoma.
Metastatic skin lesions are very rare. They often arise as large nodules and can occur anywhere on the body. In this patient, the diagnosis was confirmed by biopsy.
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Lymph Node Metastasis
Extrathoracic primary tumors are associated with a high incidence of lymph node metastasis. Lymphomas and genitourinary tract neoplasms are the most common causes of visible intrathoracic enlargement, followed by malignant melanoma and breast carcinoma. Lymphadenopathy may be hilar, mediastinal, or both. In patients with breast cancer, axillary lymph nodes may be involved.
CT may demonstrate right paratracheal involvement, as shown in a patient with non-Hodgkin lymphoma (A); subcarinal lymph node enlargement, in a patient with colon cancer (B); and bilateral axillary lymph node involvement, in a patient with non-Hodgkin lymphoma (C).
The patients shown in A and B had dyspnea on exertion. The patient shown in C appeared to be asymptomatic.
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Pulmonary Nodules
This CT scan of the chest shows multiple nodules in the lungs of a patient with thyroid cancer. Metastatic solid organ malignancies are the most common cause of multiple pulmonary nodules and account for 80% of such cases.1
The nodules are usually derived from tumor emboli that arise from invasion of tumor capillaries. The tumor emboli drain via the systemic veins and pulmonary arteries. They subsequently lodge in the small pulmonary arteries or arterioles and extend into the adjacent lung tissue.
Pulmonary nodules vary in size and location, although there is a proclivity for the better perfused lung bases. Often, multiple lesions are present. They are usually round with sharply demarcated borders. Metastases with a tendency to hemorrhage, such as choriocarcinomas, may have indistinct, fuzzy borders.
Cavitation of metastatic lesions occurs in fewer than 5% of patients.2 Calcification may develop in metastases from osteogenic sarcoma, synovial sarcoma, and chondrosarcoma. A miliary pattern is associated with thyroid carcinoma, renal cell carcinoma, sarcoma of the bone, or trophoblastic disease.
Solitary pulmonary metastases are uncommon; they account for 2% to 10% of all solitary nodules.3 The primary lesions that are more likely to produce a solitary metastasis include carcinoma of the colon, especially that of the rectosigmoid area; osteosarcoma; carcinoma of the kidney, testicle, bladder, cervix, or breast; and malignant melanoma.
Patients with pulmonary nodules may be asymptomatic; however, they will ultimately experience progressive dyspnea. Cough and hemoptysis are other typical symptoms. Needle aspiration and transbronchial biopsy are the procedures of choice to confirm the nature of the lesion. Chemotherapy is useful when the primary tumor is responsive.
REFERENCES:
1. Crow J, Slavin G, Kreel L. Pulmonary metastasis: a pathologic and radiologic study. Cancer. 1981;47: 2595-2602.
2. Dodd GD, Boyle JJ. Excavating pulmonary metastases. Am J Roentgenol Radium Ther Nucl Med. 1961;85:277-293.
3. Hassan I. Lung, metastases. Available at: http://www.emedicine.com/radio/topic404.htm. Accessed March 21, 2005.
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Bone Metastases
A chest radiograph shows erosion of the medial end of the right clavicle caused by bone metastases from renal cell carcinoma.
Metastases to bones (such as the ribs and clavicle) are common. Most patients with these metastases have bone pain, reduced mobility, and increased susceptibility to fracture at the time of presentation. These patients may benefit from palliative radiotherapy.
Most bony metastases are osteolytic, although osteoblastic metastases may be seen in patients with prostate cancer.
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Pleural Effusion
A CT scan (A) shows a massive left pleural effusion in a patient with adenocarcinoma of the stomach. Pleural effusions are often massive and tend to recur; most are exudative. Dyspnea is the most common related symptom.
Pleural effusion is associated with extensive underlying lung and systemic metastases. Lung, breast, stomach, and ovary metastases account for most cases.1
Pleural biopsy and fluid cytology establish the malignant nature of the process. Chemical pleural sclerosis, with doxycycline or bleomycin or talc instillation, is the palliative procedure of choice to prevent recurrence of the effusion.
Pleural metastases can exist in the absence of pleural effusion. A CT scan (B) shows pleural metastases in the right lung of a patient with breast cancer.
REFERENCE:
1. Johnston WW. The malignant pleural effusion. A review of cytopathologic diagnoses of 584 specimens from 472 consecutive patients. Cancer. 1985;56: 905-909.
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Pericardial Effusion
Metastatic disease may also affect the pericardium. Patients with massive pericardial effusions may present with features of cardiac tamponade, such as severe dyspnea and paradoxic pulse, and require pericardial fluid drainage.
A chest radiograph shows significant cardiac enlargement in a patient with a history of non-Hodgkin lymphoma.
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Endobronchial Disease
A chest radiograph shows complete collapse of the left lung caused by endobronchial disease in a patient with renal cell carcinoma (A). Compared with parenchymal deposits, endobronchial metastases are rare; in most cases, the primary site is clinically apparent before symptoms related to endobronchial metastases develop.1
Patients with endobronchial disease usually present with a history of hemoptysis, cough, or obstructive pneumonia. Those who have advanced disease typically exhibit complete atelectasis, characterized by opacification of the entire hemithorax and an ipsilateral shift of the mediastinum.
In a patient with an endobronchial lesion from colon cancer, bronchoscopy reveals that the bronchus opening in the right middle lobe is obliterated by endobronchial metastatic disease (B).
REFERENCE:
1. Braman SS, Whitcomb ME. Endobronchial metastasis. Arch Intern Med. 1975;135:543-547.