Lung metastases

Introduction to lung metastases A lung metastasis is a metastatic tumor that originates in other parts of the body and is transferred to the lungs via the blood or lymphatics. According to statistics, about 20 to 30% of cases of death from malignant tumors have lung metastases. The time of lung metastasis of malignant tumors varies from day to night. Most cases are metastasized within 3 years after the onset of primary cancer. It is also more than 10 years old, but there are also a few cases where lung metastases are found earlier than the primary tumor. . The primary malignant tumors that metastasize to the lungs are mostly from the breast, bones, digestive tract and genitourinary system. Most of the lung metastatic tumors are multiple lesions throughout the lungs, varying in size and density. There is no effective treatment for these advanced cancer cases. In a few cases, only a single isolated metastatic lesion in the lung may be considered for external surgery. basic knowledge The proportion of illness: 0.006% Susceptible people: no special people Mode of infection: non-infectious Complications: pleural effusion, empyema, arrhythmia

Cause of lung metastasis

Tumor factors (80%):

Pulmonary metastases are metastasis of malignant tumors in other parts of the body. The pathways can be hematogenous dissemination, lymphatic metastasis or direct invasion of adjacent organs, choriocarcinoma, breast cancer, malignant soft tissue tumors, liver cancer, osteosarcoma and Pancreatic cancer is second; there are also thyroid cancer, kidney cancer, prostate cancer and kidney embryo cancer.

Pulmonary metastases are most common in hematogenous metastasis. The blood cells are transferred to the right heart of the tumor cells and transferred to the right lung. After the tumor plug reaches the pulmonary arterioles and capillaries, it can infiltrate and pass through the blood vessel wall. Alveolar growth, the formation of lung metastases, lymphatic metastasis from the blood to the pulmonary arterioles and capillary bed, and then through the blood vessel wall into the perivascular lymph nodes, cancer cells proliferate in the lymphatic vessels, the formation of multiple small nodular lesions , often occurs in the perivascular interstitial, interlobular septum and subpleural interstitial, and spread in the lung through the lymphatic vessels, the primary disease of the tumor directly transferred to the lung into the pleura, chest wall and mediastinal malignant tumor, lung When the metastatic tumor is small, there are few symptoms, especially hematogenous metastasis. The blood in the cough and sputum is rare. A large number of lung metastases may have shortness of breath, especially lymphatic metastasis. Faster, rapid aggravation within a few weeks, chest distention, chest pain or chest pain, lung metastatic tumors change quickly, tumors increase in the short term, increase, and some After tumor resection or radiation therapy, chemotherapy, sometimes shrink or disappear.

Lung metastasis prevention

Because lung metastases are metastatic tumors from other parts of the body that are transmitted by blood. Therefore, prevention is mainly based on active treatment of primary tumors. Pay attention to proper rest, do not master the combination of movement and rest, rest well, is conducive to the recovery of the body; exercise can enhance physical strength and enhance disease resistance, and the combination of the two can better recover.

Pulmonary metastases complications Complications, pleural effusion, empyema, arrhythmia

1, pleural effusion

Most cases caused by tumors are called malignant pleural effusion. Clinically, malignant pleural effusion is caused by direct invasion of malignant tumor or pleural metastasis. There are also a few patients whose pleural effusion appears as the first symptom of the tumor. It is generally believed that pleural effusion It usually indicates that the disease has entered the advanced stage. When the amount of fluid is small (initial or absorption period), obvious chest pain can occur. Especially when it is deep breathing, the amount of fluid can be asymptomatic, and breathing occurs when there is moderate or large amount of fluid. Difficulties, the effusion formation rate is slower, the breathing difficulty is not significant, the short-term formation of a large number of pleural effusion patients with severe breathing difficulties, the original poor lung function of patients with pleural effusion symptoms, X-ray examination showed rib angle becomes dull, ultrasound examination It can help the center to determine the presence or absence of pleural effusion, lesions and pleural effusion, and to identify pleural effusion and pleural thickening. According to the appearance of pleural effusion and pleural effusion routine, it can be judged whether it is leaking or exudative, and can also be based on serum and pleural protein content. The content of lactate dehydrogenase is judged whether it is exudative pleural effusion.

2, empyema

Due to the influence of tumors, the patient's immunity is reduced and it is more susceptible to infection. If the pleural cavity is infected by pathogenic bacteria, it forms purulent. Patients often have chest pain, fever, shortness of breath, fast pulse, discomfort, and loss of appetite.

3, arrhythmia

Its clinical manifestations are a sudden or irregular palpitations, chest pain, dizziness, discomfort in the precordial area, nausea, shortness of breath, coldness of the hands and feet and syncope, and even unconsciousness. A small number of patients with arrhythmia can be asymptomatic. Only the ECG changes.

Symptoms of lung metastases Common symptoms Dysphagia

The severity of symptoms is closely related to the type of tissue, metastasis pathway, and extent of involvement of the primary tumor. Most cases have symptoms of primary cancer. Early lung metastases have no obvious respiratory symptoms. If lung lesions are extensive, dry cough and blood stasis may occur. And breathing difficulties, such as concurrent cancerous lymphangitis, a large number of pleural effusion, atelectasis or superior vena cava pressure, the breathing difficulties are more obvious, secondary infection may have fever, pulmonary hypertrophic osteoarthritis and The clubbing is less common than the primary lung cancer. The X-ray findings of metastatic lung tumors are most common in isolated or multiple nodular lesions in the middle and lower lung fields, with a diameter of 1 to 2 cm and a smooth edge. Increase and increase, can be merged into a large block, choriocarcinoma is often a spherical follicle of cotton, the metastatic lung cancer from the digestive tract can be diffuse miliary or reticular shadow, metastatic squamous cell carcinoma, even can form atypical Cancerous cavities, a small number of metastatic breast cancers with slower growth, can form diffuse pulmonary fibrosis, pleural effusion caused by metastatic cancer in women, mostly from advanced breast cancer.

1, generally no obvious symptoms, mostly found in chest X-ray examination.

2, a small number of patients have cough, sputum with blood and other symptoms.

Early metastatic symptoms of lung metastases are mild or absent, often found during routine X-ray examination of the chest, or recurrence between 6 months and 3 years after radical surgery or radiotherapy, which means that the symptoms vary with the location of the metastasis. If the metastasis occurs in the pulmonary interstitium, it is often without clinical symptoms when the isolated nodules; if the metastases are located in the endobronchial membrane, patients may have respiratory symptoms, clinical chest pain is common in patients with rib metastasis; bronchial mucosa in a few cases A small amount of hemoptysis may occur when invaded, but large hemoptysis may occur in lung metastasis of choriocarcinoma. When the metastasis invades the pleura, the main bronchus or adjacent structures, the same symptoms as primary bronchogenic lung cancer may occur, such as cough and sputum. Bloodshot, chest pain, chest tightness, shortness of breath, etc., the symptoms appear earlier, suggesting that metastases involve the bronchus, if accompanied by mediastinal metastasis, the patient may present as a dumb, superior vena cava syndrome, chancre and esophageal or tracheal compression symptoms, Occasionally, the tumor causes acute pulmonary embolism, which is characterized by progressive dyspnea.

Examination of lung metastases

1, x-ray inspection:

(1) Hematogenous lung metastases:

1 typical performance, multiple lungs, spherical lesions of varying sizes, smooth edges, uniform density, more common in the middle and lower lung fields.

2 Both lungs are widely diffuse miliary shadows with blurred boundaries.

3 single large nodular lesions, marginal smooth, can be lobulated, uniform density, the most common colon cancer.

4 lesions can occur in the cavity or calcification, the cavity is more common in the head and neck and genital squamous cell carcinoma, calcification is more common in osteosarcoma, chondrosarcoma.

5 can occur spontaneous pneumothorax, more common in osteosarcoma or fibrosarcoma.

6 very few manifestations of pulmonary hypertension.

7 pneumonia-type metastasis is rare, manifested as flaky blurred shadow, more common breast cancer metastasis.

8 bronchial metastases are also rare, kidney cancer and colon are common, manifested as signs of bronchoconstriction and obstruction.

(2) Lymphatic metastasis:

1 side or bilateral mediastinum, hilar lymph nodes.

2 The lungs are enhanced in texture, and the thin strips along the lung texture are accompanied by fine nodules or reticular shadows.

3 common spacing lines (Kerley A and B lines), the interlobular fissure is also thickened.

4 pleural effusion.

(3) Direct spread:

1 lesions are mainly located in the mediastinum, chest wall, or transverse diaphragm.

2 The lungs were violated to varying degrees.

2, CT examination:

1CT is the most effective method for finding small lung metastases or evaluating mediastinal metastasis.

2CT can find more lesions.

3 nodules are distributed in the outer third of the lower lobe, within 3 cm from the surface of the pleura.

4 easier to show voids, calcification.

5 High-resolution CT thin-layer scanning showed a reticular change in the interstitial lung with small nodules and irregular thickening of the interlobular septa.

3. MRI examination:

MRI is generally not used to examine lung metastases, but MRI is helpful in understanding the primary tumor.

Diagnosis and differentiation of lung metastases

Differential diagnosis

In general, the main distinguishing points between lung metastasis and other diseases are: rapid changes, tumor enlargement and increase in the short term, and some may be reduced or disappeared after primary tumor resection or radiotherapy, after chemotherapy.

For the differential diagnosis of lung metastases, it can be divided into two situations:

First, the performance of special lung metastases should be differentiated from the following diseases:

1, tuberculosis: often single hair, hollow, mostly thick-walled fissure-like, visible curvature, ring or diffuse spotted calcification, often connected with the shadow of the lungs between the lungs, there are satellite stoves in the nearby lung field.

2, Staphylococcus aureus pneumonia: characterized by acute onset, clinical symptoms, high fever, the primary performance can appear lung balloon, gas-liquid level, etc., follow-up observation changes quickly.

3, cystic bronchiectasis: often hemoptysis, lesions along the bronchial distribution, showing a grape string, the performance is more typical.

4, pulmonary fungal disease: no characteristic performance, and metastasis identification is difficult, need to be combined with clinical history or sputum examination, when the lesion appears typical air crescent sign, the lesion is in the middle or late stage.

Second, the clinical often encounter atypical lung metastasis, it needs to be differentiated from other non-malignant diseases of the lung.

Radiological manifestations include: cavities, calcification, peritumoral hemorrhage, pneumothorax, airway lesions, tumor embolism, endobronchial metastasis, single metastasis, intratumoral vasodilation, sterilized metastases, benign tumors Lung metastasis.

1, hollow

Cavities are rare, accounting for only 4%, which is lower than the incidence of primary lung cancer (9%), 70% of which is squamous cell metastasis, but recent studies have shown that there is a spatial metastasis of adenocarcinoma and squamous cell carcinoma on CT. There is no significant difference in the probability. In addition, metastatic sarcoma can also be hollow, and combined with pneumothorax, chemotherapy can also lead to the formation of cavities. The mechanism of cavitation is often difficult to determine. It is generally considered to be caused by tumor necrosis or invasion of the bronchi. The cavity is more common with irregular thick walls. The lung metastasis of sarcoma or adenocarcinoma can be a thin-walled cavity. The sarcoma metastasis can be accompanied by a cavity, but often with a pneumothorax.

2, calcification

Calcification of the pulmonary nodules often suggests benign, most common in granulomatous lesions, followed by hamartoma, but some malignant tumors may also have calcification or ossification in the pulmonary metastatic nodules, which can be seen in osteosarcoma, chondrosarcoma , synovial sarcoma, giant cell tumor of bone, colon cancer, ovarian cancer, breast cancer, lung metastasis of thyroid cancer and treated metastatic choriocarcinoma, calcification mechanisms include: 1 bone formation (osteosarcoma or chondrosarcoma); 2 nutrition Poor calcification (thyroid papillary carcinoma, giant cell tumor of bone, synovial sarcoma or treated metastatic tumor); 3 mucinous calcification (gastrointestinal and breast mucinous adenocarcinoma), CT is the accurate method to find calcification, but It is not possible to distinguish between metastatic nodules and granulomatous lesions or calcifications in hamartomas.

3, peritumoral bleeding

A typical CT manifestation is a halo-like density or halo-like halo around the nodules, but the halo sign is not specific, but can also be seen in other diseases such as invasive aspergillosis, candidiasis, Wegener Granuloma, tuberculoma with hemoptysis, bronchioloalveolar carcinoma and lymphoma, chest radiographs with irregular marginal multiple nodules, angiosarcoma and choriocarcinoma lung metastases are most prone to bleeding, possibly due to fragile neovascular wall Easy to break.

4, spontaneous pneumothorax

Rarely, the literature reports that the lung metastasis of osteosarcoma is most likely to be complicated by pneumothorax. In 5% to 7% of cases, pneumothorax of other sarcomas or necrotic malignant tumors has also been reported. The mechanism may be necrosis of subpleural metastases to form bronchial pleura. Due to sputum, patients with osteosarcoma should be highly alert to lung metastases when they develop pneumothorax.

5, air gap lesions

The intrapulmonary metastasis of adenocarcinoma can be similar to that of bronchioloalveolar carcinoma, spreading along the intact alveolar wall to the lungs. The radiological findings are similar to pneumonia. It can be expressed as a gas-containing gap nodule with consolidation of gas-containing bronchus, focal or Diffuse frosted glass density, pulmonary nodules with halo sign, can be seen in gastrointestinal adenocarcinoma, lung metastasis of breast and ovarian adenocarcinoma, because this type of metastatic tumor is histologically similar to bronchioloalveolar carcinoma Therefore, the diagnosis of bronchioloalveolar cancer should be preceded by the presence of extrapulmonary adenocarcinoma.

6, tumor embolism

In patients with solid malignant tumors, 2.4% to 26.0% of the patients can see tumor thrombus under the microscope. The tumor thrombus is often small, often located in the branches of small or medium pulmonary artery. Patients with malignant tumors have acute or subacute dyspnea and low Oxygenemia, while the chest radiograph is normal, often suggests the possibility of tumor embolization. At this time, the radionuclide perfusion scan often shows multiple, small peripheral sub-segment perfusion defects. Typical pulmonary angiography shows delayed pulmonary filling. The third and fourth grade pulmonary artery branches were suddenly cut and distorted, and the sub-pulmonary filling defects were seen. The CT findings of the tumor thrombus showed multiple localized expansion of the peripheral sub-segmental pulmonary artery branches, bead-like changes, and the pleural effusion caused by pulmonary infarction. For the wedge-shaped solid shadow of the base, CT and pulmonary angiography can find large tumor thrombus in the main, leaf or segmental pulmonary artery. The primary tumor is common in liver cancer, breast cancer, kidney cancer, stomach cancer, prostate cancer and choriocarcinoma.

7, endobronchial transfer

The incidence is low, and the visible intramural metastasis is only seen in 2% of cases. The primary tumor is often kidney cancer, breast cancer and colorectal cancer. It is mostly characterized by lobe or one-sided atelectasis. Endobronchial metastases, but difficult to differentiate from primary bronchial carcinoma, the route of endobronchial metastasis is: 1 by inhaling human tumor cells, lymphatic or blood direct dissemination to the bronchial wall; 2 lymph nodes or lung parenchyma Tumor cells grow along the bronchial tree and break through the bronchial wall to form intraluminal lesions.

8, single transfer

The incidence of single lung metastases was low in patients without a history of malignant tumors (0.4% to 9.0%). In patients with a history of extrathoracic malignant tumors, 25% to 46% of single lung nodules were metastatic tumors, including head and neck. Patients with a history of bladder, breast, cervix, bile duct, esophagus, ovary, prostate, and gastric cancer have a much higher incidence of primary lung cancer than single metastatic disease; whereas melanoma, sarcoma, and testicular cancer have a single lung metastasis. Primary lung cancer is more common.

9, intratumoral vasodilation

On the enhanced CT, dilated, twisted tubular reinforced structures are sometimes seen in metastatic lung nodules, which are tumor vasculature, commonly found in sarcomas such as alveolar soft-part sarcoma or leiomyosarcoma.

10, inactivated metastatic tumor

Some metastatic pulmonary nodules are unchanged or slightly smaller after adequate chemotherapy. After surgical resection, necrotic nodules are found with or without fibrosis. No surviving tumor cells are called inactivated metastases. After squamous cell carcinoma and testicular cancer metastasis and chemotherapy, such nodules are radiologically difficult to distinguish from residual viable tumors. Biomarkers such as human chorionic gonadotropin (p-HCG), alpha-fetoprotein (AFP) The detection helps to determine its activity, and the biological activity of the PET examination nodules also contributes to the differential diagnosis and, if necessary, a needle biopsy.

11, benign tumor lung metastasis

Intrapulmonary metastasis of benign tumors is rare, and is still benign in histology, often derived from uterine leiomyoma, hydatidiform mole, giant cell tumor of bone, chondroblastoma, salivary gland pleomorphic adenoma and meningioma, in radiation It is difficult to distinguish from malignant tumor lung metastasis. Compared with malignant tumors, metastatic lung nodules of benign tumors often grow slowly.

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