Lung nodules



Overview

Imaging manifestations for the diameter of ≤ 3 cm focal, rounded, increased density of the lung shadow nodule is small, most of the obvious symptoms, the progress of the disease can be cough, sputum, hemoptysis, chest pain and other manifestations of a variety of diseases can be manifested in the lung nodule, such as pulmonary malformation, tuberculosis ball, lung cancer, etc. to the cause of the treatment is based on the main, such as anti-tuberculosis, anti-tumor treatment

Definition

Pulmonary nodule, also known as a lung nodule, is a focal, round or irregularly shaped lesion with a maximum diameter of ≤3 cm in the lung on imaging [1-7].

Lesions with a diameter of >3 cm are called lung masses and have a high likelihood of lung cancer [3].

They have clear or unclear borders, are shadows of increased density, and may be single or multiple.

It is generally accepted that >10 diffuse multiple lung nodules are mostly metastases of malignant tumors or benign lesions, such as inflammatory lung diseases due to infection [3].

Lung nodules are an imaging manifestation of not one specific disease but multiple diseases. They may be benign, malignant, or at the junction of benign and malignant, and may not always be lung cancer.

The majority of lung nodules found on screening imaging are benign. In general, the larger the nodule the greater the probability of malignancy [1].

In recent years, the detection rate of lung nodules has been increasing due to the popularization of physical examinations and advances in imaging technology.

There are no special dietary precautions for lung nodules, but smoking should be strictly stopped to reduce the possibility of lung cancer.

Classification

Lung nodules can be categorized into different types according to the nature, size, density and number of nodules, and there are differences in treatment and prognosis among different subtypes.

Classification according to the nature of nodules

Benign lung nodules: e.g. lung malformation tumor, tuberculosis ball, pneumonic pseudotumor, pulmonary nodular disease, etc.

Malignant lung nodules: e.g. primary lung cancer, metastatic lung cancer, etc.

Classification according to the maximum diameter of nodules

<5 mm for tiny nodules, malignant probability <1%.

5-10 mm are small nodules with 6%-28% probability of malignancy.

Nodules >10 mm have a 33% to 60% probability of malignancy [1].

Classification of nodules according to their density under imaging

Solid nodules: round or round-like hyperdense shadows in the lungs, with lesions dense enough to obscure the vascular and bronchial shadows that travel through them.

Sub-solid nodules: all lung nodules containing ground glass density are called sub-solid lung nodules. These include pure ground-glass nodules, partially solid nodules with both ground-glass and solid densities.

Classification according to the number of nodules

Isolated pulmonary nodule: a single soft tissue shadow with clear borders, increased density, diameter ≤ 3 cm, and surrounded by air-containing lung tissue.

Multiple pulmonary nodules: are 2 or more foci and are categorized as primary and secondary [9-13].

Morbidity

Lung nodules are most common in people ≥40 years of age who have been smoking for a long time [2].

Multiple lung nodules are more common, accounting for up to 50% of cases.

Etiology

Lung nodules are a common diagnosis, and their etiology varies depending on the diagnosis of nodule pathology.

Pathogenic causes

Benign lung nodules

Lung misshapen tumor

The etiology of pulmonary malformation tumor is unclear. It is currently believed that pulmonary malformation is a congenital tumor-like malformation.

Tuberculosis Ball

Tuberculosis balls, also known as tuberculomas, mostly evolve from secondary tuberculous lesions in the lungs.

Pneumonic pseudotumor

The etiology of pneumonic pseudotumor is poorly understood. It may be due to non-specific inflammation caused by bacterial or viral infections that remain untreated for a long period of time leading to the formation of a tumor-like mass.

Pneumatoid pseudotumor is composed of various inflammatory cells and mesenchymal tissues, including plasma cells, lymphocytes, histiocytes, mast cells, and spindle-shaped mesenchymal cells.

Malignant nodules in the lung

Primary Lung Cancer

The cause of primary lung cancer is still not completely clear, and it may be related to the following factors.

Smoking and passive smoking.

History of chronic obstructive pulmonary disease.

Occupational exposures such as exposure to specific substances such as asbestos, radon, beryllium, chromium, cadmium, nickel, silica, soot and coal smoke.

Family history of lung cancer and genetic predisposition, etc.

Metastatic Lung Cancer

Metastatic lung cancer is caused by malignant tumors of various organs of the whole body metastasizing to the lungs through blood circulation, direct infiltration and lymphatic channels, and it is a late-stage lesion.

It is mostly metastasized from breast cancer, thyroid cancer, kidney cancer and other cancers.

Symptoms

Smaller lung nodules may be asymptomatic, while larger nodules may be accompanied by cough, sputum, chest pain, hemoptysis, fever and other symptoms.

Main Symptoms

Benign lung nodules

Lung malformation tumor

Lung malformation tumor is slow-growing and has a long course. It is usually asymptomatic, and the lesion is mostly found by chest radiograph during physical examination. Depending on the site of occurrence, it can be divided into intrapulmonary and endobronchial type.

Cough, sputum, hemoptysis, wheezing, chest pain, fever and other symptoms may appear when the lesion increases in size, especially the endobronchial type, which may cause respiratory distress in severe cases.

Tuberculosis ball

Tuberculosis ball is a relatively stable lesion, which can remain static for a long time and is usually asymptomatic.

However, when the body’s resistance is lowered, the lesion may progress and present with dry cough, chest pain, hemoptysis, low-grade fever, malaise, loss of appetite, weight loss, night sweats and other manifestations.

Pneumonic pseudotumor

About 1/3 of patients with pneumonic pseudotumor have no clinical symptoms and are only occasionally found on X-ray examination.

2/3 of the patients have a history of chronic bronchitis, pneumonia, etc. They may have cough, cough sputum, low-grade fever, chest pain, blood in sputum, or even hemoptysis.

[Tip] For more detailed symptoms, please refer to read Lung Malignant Nodule, Tuberculosis, Pneumonic Pseudotumor.

Malignant Nodules in Lung

Primary Lung Cancer

Primary lung cancer usually has no obvious symptoms in the early stage, and symptoms such as coughing, coughing up sputum, hemoptysis, dyspnea, fever, weight loss, and fatigue appear only after the disease has progressed to a certain stage.

Metastatic Lung Cancer

In addition to the above primary lung cancer symptoms, metastatic lung cancer also has primary lesion symptoms.

Tips] For more detailed symptoms, please refer to reading Lung Cancer, Metastatic Lung Cancer.

Seek medical attention

After symptoms such as cough, sputum, hemoptysis, chest pain, fever, etc. are present, it is recommended to organize relevant information and consult the Department of Respiratory Medicine first.

Department of Medicine

Respiratory Medicine

Please consult the Department of Respiratory Medicine for symptoms such as cough, sputum, blood in sputum or hemoptysis, chest pain and fever.

Thoracic Surgery

Please consult the Department of Thoracic Surgery when nodules are found in the lungs on chest imaging (X-ray, chest CT, etc.).

Oncology

When malignant lung nodules are diagnosed and comprehensive anti-tumor treatment such as surgery, radiotherapy and chemotherapy is required, you may also consult the Department of Oncology.

Preparation for medical treatment

Consultation: Registration, Preparation of Documents, Frequently Asked Questions

Tips for Medical Consultation

Patients may need to undergo a chest X-ray or CT examination. Avoid wearing metallic clothing such as shirts with buttons, blouses with sequins, and dresses with zippers and buttons.

Record the symptoms, duration and other relevant information for your doctor’s reference.

It is recommended that a family member accompanies you to the doctor’s office.

Preparation Checklist for Medical Consultation

Symptom list

Pay particular attention to the time of onset of symptoms, special manifestations, etc.

Is there any cough or sputum, and how long has it lasted?

Is there blood in the sputum or hemoptysis?

Any chest pain, fever, etc.?

Is there a dry cough, low-grade fever in the afternoon, or fatigue?

Has there been any change in weight recently? How is your appetite?

List of medical history

Are you a smoker, how many years have you been smoking, and how many cigarettes per day?

What is your occupation?

Is there any family history of malignant tumors such as lung cancer?

Are there any other concomitant diseases such as tuberculosis, chronic obstructive pulmonary disease, etc.?

Are there any drug or food allergies?

Checklist

Examination results in the past six months, which can be brought to the doctor’s office

Specialized tests: histopathology, bronchoscopy

Laboratory tests: routine blood test, biochemical test, tuberculin test.

Imaging tests: CT, magnetic resonance (MRI), PET-CT, etc.

Diagnosis

Preliminary diagnosis should be made by combining the medical history, clinical manifestations, laboratory and imaging results, and final diagnosis should be made by pathologic examination.

Diagnostic basis

Medical history

Patients may have a history of the following, but not everyone with the following medical history will have lung nodules.

History of smoking and passive smoking (secondhand smoke).

History of tuberculosis.

History of chronic obstructive pulmonary disease (COPD).

History of occupational exposure to asbestos, radon, beryllium, chromium, cadmium, nickel, silica, soot and coal smoke.

Family history of malignant tumors such as lung cancer.

History of primary tumors, such as thyroid cancer and breast cancer.

Clinical manifestations

Symptoms

There are no obvious symptoms when the lung nodules are small.

Cough, sputum, blood in sputum or hemoptysis, chest pain, fatigue and so on.

Physical signs

Usually there are no abnormal physical signs.

Malignant nodules in the lungs may have enlargement of axillary lymph nodes, supraclavicular lymph nodes and other superficial lymph nodes.

Laboratory Tests

General examination

Patients are required to undergo necessary general tests such as blood counts, liver and kidney functions, electrolytes, and coagulation analysis before treatment.

There may be no specific changes, but it can determine the general condition of the patient and understand whether the patient has infection, anemia, thrombocytopenia, abnormal liver and kidney functions, electrolyte disorders, and abnormal coagulation function.

Tumor markers

Commonly used tumor markers: such as carcinoembryonic antigen (CEA), neural specific enolase (NSE), cytokeratin fragment 19 (CYFRA21-1), squamous cell carcinoma antigen (SCCA), gastrin-releasing peptide precursor (pro-GRP), etc., which have a certain degree of reference significance.

Novel tumor markers: such as tumor-associated antigen autoantibodies, circulating tumor cells (CTC), circulating tumor DNA (ctDNA) and other blood components.

It should be noted that early lung cancer is often not accompanied by elevated tumor markers, and elevated tumor markers are not equal to lung cancer, and need to be combined with other tests to make a comprehensive judgment.

Tuberculin test

It can find out whether there is Mycobacterium tuberculosis infection.

Sputum Mycobacterium tuberculosis test

It can know whether there is Mycobacterium tuberculosis infection.

It is the main method to confirm the diagnosis of tuberculosis, and is also the main basis for formulating chemotherapy program and judging the effect of treatment. However, a negative Mycobacterium tuberculosis test cannot exclude tuberculosis, and it is necessary to combine with other tests to make a comprehensive judgment.

There are mainly smear method and culture method, and the sensitivity of culture method is higher than that of smear method, which is often used as the “gold standard” for the diagnosis of tuberculosis.

Imaging

CT

CT is the preferred method to show sub-solid nodules, and low-dose CT (LD-CT) scanning of the chest is recommended, on the basis of which thin-layer high-resolution CT, target scanning or target reconstruction is emphasized.

When the lesion is closely related to the pulmonary vasculature or when lymph node metastasis is suspected, chest CT enhancement scan is feasible.

CT examination of other parts of the body, including brain, liver and kidney, can help doctors clarify whether there are distant metastases.

It has high sensitivity, specificity and accuracy for qualitative diagnosis of lung nodules.

Positron Emission Computed Tomography (PET-CT)

PET-C examination has high sensitivity and specificity in the diagnosis, staging and treatment evaluation of lung cancer.

PET-CT examination is feasible for suspicious lung nodules found in screening.

However, for lung nodules <8 mm in diameter, the PET-CT positivity rate is low, and close follow-up is needed to avoid missed diagnosis.

For partially solid nodules >8 mm in diameter that cannot be characterized, the addition of a delayed scan is recommended to help increase the positivity rate.

PET-CT is not recommended as a routine primary screening tool for lung cancer.

Bronchoscopy

Bronchoscopy includes direct bronchoscopic brushing, biopsy, or bronchoalveolar lavage to obtain cytologic and histologic diagnoses.

Endobronchial ultrasound-guided lung biopsy (EBUS-TBLB) improves the positive rate of lung nodule biopsy.

Pathologic examination

Trans-thoracic wall lung puncture biopsy (TTNB)

Trans-thoracic wall lung puncture biopsy is one of the commonly used methods to diagnose lung cancer, in which CT, ultrasound or MRI-guided puncture biopsy is performed to obtain tissue.

The success rate of trans-thoracic wall puncture biopsy with stents, templates, navigation and other assistive devices has been further improved in recent years, and the accuracy of lung cancer diagnosis can reach 74% to 95%.

Literature reports that TTNB needle tract metastasis is rare, with an incidence of 0.012% to 0.061%, and the application of coaxial puncture biopsy technique can reduce the incidence of needle tract implantation metastasis, and also complete ablation and other treatments at the same time [8].

Surgical biopsy　

For high-risk lung nodules that cannot be pathologically diagnosed by non-surgical biopsy (including bronchoscopy and transthoracic wall lung puncture biopsy), thoracoscopic resection of the lesion is feasible to clarify the pathologic diagnosis.

Determination of benignity and malignancy

The size, shape, margins, internal structure, and dynamic changes of the lung nodule can help to determine the benign or malignant nature of the nodule. Imaging may also further assist in distinguishing the benign or malignant nature of lung nodules [4].

Appearance

Nodule size

As the size of a lung nodule increases, its probability of malignancy also increases.

However, changes in lung nodule size have limited value in the qualitative diagnosis of ground-glass lesions and need to be closely combined with changes in morphology and density.

Nodule morphology

Most malignant lung nodules have a round or round-like shape.

A higher proportion of malignant sub-solid nodules have an irregular pattern compared with malignant solid nodules.

Nodule margins

The margins of malignant nodules are more often clear, but they are not smooth or lobulated, and the margins are rough or even burred.

Inflammatory pulmonary nodules tend to have fuzzy margins.

Benign non-inflammatory lung nodules tend to have clear, neat or even smooth margins.

Internal structure

Nodule density

Pure ground-glass lung nodules, especially those <5 mm, often suggest atypical adenomatous hyperplasia (AAH); however, there are also microinvasive adenocarcinomas (MIA) or invasive adenocarcinomas (IA) that present as pure ground-glass nodules.

The majority of persistent ground-glass nodules are malignant or have a tendency to progress to malignancy.

The higher the mean CT value of the ground glass nodule the higher the probability of malignancy and vice versa.

Partially solid nodules with uneven density or containing vacuoles often suggest a high likelihood of malignancy.

Bronchial changes　

If the bronchial tubes are encapsulated with localized wall thickening, or if the lumen of the encapsulated bronchial tubes is irregular, it suggests the possibility of malignancy.

Vascular changes　

The presence of blood vessel penetration and vascular deformation in the lesion suggests malignancy.

Functional imaging

PET-CT scanning is not recommended for pure ground glass nodules ≤8 mm in diameter on chest LD-CT.

For solid nodules >10 mm PET-CT scanning may be performed to assess the likelihood of malignancy.

Assessment of the probability of clinical malignancy

Assessing the probability of malignancy of a lung nodule based on clinical information and imaging features prior to biopsy can help in the selection of appropriate follow-up methods and modes of follow-up.

≥40 years of age with history of malignancy from smoking or secondhand smoke 400 cigarettes/year

Non-surgical biopsy no clear evidence of malignancy suspicious for malignancy

Non-surgical biopsy

No clear evidence of malignancy

Suspected malignant tumor

CT follow-up tends to dissipate and continues to shrink ≥ 2 years stable and continues to increase Pure ground-glass nodule with a solid component that is gradually increasing in size

CT follow-up

Tend to dissipate and continue to shrink ≥ 2 years stable

Persistent enlargement of purely ground-glass nodules with a solid component with a progressive increase in the solid component.

Caution:

Independent risk factors for malignancy include advanced age, current or former smoker, short duration of smoking cessation, history of extrathoracic tumor 5 years prior to the discovery of the lung nodule, large diameter of the nodule, pleural pulling, high serum CEA level, burr and bronchial signs, lobulated margins, irregular shape, mixed density, and absence of calcification [8].

If the patient is accompanied by prolonged tension, depression or anxiety and other mood disorders, which have seriously affected the patient’s quality of life, and for patients found to have psychological disorders that do not improve with aggressive psychotherapy or medication, an increase of 1 risk rating may be considered for such patients.

Differential Diagnosis

The description of lung nodules is mainly an imaging manifestation, and the internal structure and tissue composition of the nodules require further refinement of pathologic examination, so the differential diagnosis of lung nodules is mainly between different nodules.

Lung malformation tumor

The imaging manifestation of pulmonary malformation tumor is a solitary, smooth-margined, isolated lesion with uniform or non-uniform density, which is regularly rounded or lobed, with “popcorn-like” calcification, no burr, no cavity, and no sign of pleural depression.

Tuberculosis ball

Tuberculosis ball is usually located in the apical posterior segment of the upper lobe or the dorsal segment of the lower lobe, and there may be small fissure-like cavities with calcification inside the tumor, surrounded by scattered satellite foci and scarring focal emphysema.

Lung cancer

Lung cancer mostly has imaging features such as burr margins, lobulation, vascular cluster sign, pleural depression sign, etc. Calcification rarely occurs, or there are punctate or eccentric calcifications in larger tumors, which do not have internal fat density, and cavities may be formed inside some lung cancer lesions.

Treatment

Aim of treatment: treat the primary disease, maximize the relief of symptoms and improve the quality of life of patients.

Treatment principle: firstly, the nature of the lung nodule should be clarified, and surgery and other treatments should be carried out according to the size and nature of the nodule.

Lung malformation tumor

Regular follow-up

Patients who are clearly diagnosed with intrapulmonary malunion can be followed up regularly without surgical resection for the time being.

Bronchoscopic intervention

Suitable for endobronchial malformation tumor. The efficacy is clear and the safety is high.

Bronchoscopic interventional therapy techniques include high-frequency electricity, freezing, argon plasma coagulation, laser and so on.

Surgical treatment

Indications

Intrapulmonary malignant tumor: atypical imaging features, difficult to distinguish from malignant tumors; heavy psychological burden due to unknown diagnosis; lesion diameter >25 mm or its obvious tendency to increase in size.

Endobronchial malignant tumor: airway obstruction has caused irreversible lung destruction, or the benign or malignant nature of the lesion is uncertain.

Surgical Procedures

Simple tumor debulking or lung wedge resection, avoiding lobectomy or total lung resection as much as possible.

Tuberculosis ball

Drug treatment

Patients should receive regular anti-tuberculosis drug treatment and regular review. However, clinical experience has proved that most of the effects of tuberculosis ball internal medicine treatment are relatively poor.

Surgical treatment

Once a TB ball is detected, if there is no other active lesion in the lungs, surgical resection is recommended if the physical condition permits. After surgery, the patient should continue to receive regular anti-tuberculosis treatment for not less than 6 months to prevent recurrence.

Pneumonic pseudotumor

Since it is difficult to diagnose pneumonic pseudotumor before surgery, especially to distinguish it from lung cancer, and there is a possibility of cancer, therefore, if it is not absorbed after anti-inflammatory treatment, surgery is recommended.

Intraoperative pathological frozen section examination is required to clarify the diagnosis. After determining the benign nature, surgery is based on the principle of preserving normal lung tissue as much as possible.

Inflammatory pseudotumor located on the surface of the lungs, can do lung wedge resection.

Inflammatory pseudotumor located in the lung parenchyma can be resected by segmental resection or lobectomy. Except for huge masses and those that have invaded the main bronchus, total lung resection is usually not done.

Lung Cancer

The treatment of lung cancer generally adopts the principle of combining multidisciplinary comprehensive treatment with individualized treatment for the whole management.

According to the physical condition of patients, pathological and histological types and molecular typing of tumors, scope of invasion and tendency of development, a multidisciplinary integrated treatment mode is adopted.

Through the planned and rational application of surgery, radiotherapy, chemotherapy, molecular targeted therapy and immunotherapy, etc., with a view to maximizing the extension of the patient’s survival time, improving the survival rate, controlling tumor progression and improving the patient’s quality of life.

Tip: For more on treatment, please refer to related terms such as lung cancer.

Prognosis

Different types of lung nodules have great differences in cure. Generally speaking, benign lung nodules are mostly cured well after reasonable treatment, and the cure of malignant lung nodules is related to the stage and pathologic typing.

Cure status

Lung malignant tumor

The patients can be cured after reasonable treatment, and the cure status is good.

Tuberculosis ball

Small tuberculosis balls are potentially curable with long-term drug treatment.

The effect of anti-tuberculosis treatment for large tuberculosis balls is difficult to guarantee, and surgical treatment combined with regular anti-tuberculosis treatment can be cured.

Pneumonic pseudotumor

Most of them recover well after surgical resection and can be cured.

Lung Cancer

According to the results of the 2017 meta-analysis in the 8th edition of the tumor staging manual developed by the American Joint Committee on Cancer (AJCC), the survival rates for lung cancer are as follows [10-12]:

Non-small cell lung cancer (NSCLC)

Stage IA patients have a 5-year survival rate of approximately 80%.

Stage II patients have a 5-year survival rate of about 55%.

The 5-year survival rate drops to about 20% in stage III patients.

The 5-year survival rate for stage IV patients is just under 5%.

Small cell lung cancer (SCLC)

The 5-year survival rate for stage I patients is about 50%.

Stage II is about 25%.

Stage III drops to about 10%.

Stage IV is less than 3%.

Survival rates for malignant lung nodules can be found in this data.

Special Reminder

The overall survival time of cancer patients can be roughly predicted by the 5-year survival rate, which refers to the proportion of patients whose tumors survive for more than 5 years after various comprehensive treatments. the probability of recurrence after 5 years is so low that it can generally be regarded as a clinical cure.

Statistical data such as the 5-year survival rate are for clinical studies only and do not represent an individual’s specific survival period.

Survival should be analyzed in the light of the stage of the disease, physical condition, and whether the patient has received standardized treatment and regular follow-up, etc. Consultation with the physician is recommended.

Prognostic factors

Prognostic factors refer to the factors that affect the overall survival and quality of life of patients.

Among the lung nodules pathologically diagnosed as lung cancer, solid nodules have the highest degree of malignancy, followed by partially solid nodules, and pure ground glass nodules have the best prognosis.

The later the pathologic stage, the worse the prognosis.

The lower the degree of pathological differentiation, the worse the prognosis.

Daily

There is no special diet for patients with lung nodules, and the most important thing is to improve the lifestyle, especially to quit smoking and drinking, and to have a regular routine.

They should learn to self-monitor their condition and follow strictly the requirements for review.

Daily management

Lifestyle

Stop smoking and drinking, avoid strenuous work, have a regular routine, avoid staying up late and get enough sleep.

Maintain a healthy body weight, take appropriate activities such as slow walking, tai chi, qigong, breathing exercises, etc., and avoid crowded places.

Improve immunity and prevent lung infections.

Diet management

Reasonable dietary arrangement, so as to achieve a light diet, balanced nutrition, and a rich variety of food.

Intake of vitamin-rich fresh fruits and vegetables can be increased to supplement the vitamins needed by the body and promote recovery.

Eat more protein-rich food, such as eggs, milk, lean meat and fish.

Cold, raw, stimulating, pickled, fried and deep-fried foods, such as fried chicken and chili peppers, should be avoided.

Psychological support

Lung nodules have a higher probability of being benign, and even if they are diagnosed as malignant, they are likely to be in the early stages of the disease due to their small size, and timely treatment is usually more effective.

Therefore, patients are advised to maintain a good mood and mindset, face the disease positively and build up confidence in overcoming the disease.

If psychological pressure is high, they should learn to confide in friends and family members to avoid the accumulation of pressure resulting in mental illness, and seek help from a psychiatrist if necessary.

Family members should give the patient sufficient company, create a warm family atmosphere, comfort the patient and help him/her to overcome the difficulties.

Disease monitoring

Patients should pay attention to observe their own situation, if symptoms such as coughing, coughing up sputum, hemoptysis, chest pain, etc. recur or the above symptoms gradually aggravate, they should consult a doctor in a timely manner.

Follow-up review

Purpose of review

Regular follow-up and dynamic observation is the most important treatment for patients with incipient lung nodules, which can monitor the changes of the nodules and make timely and appropriate treatment.

Timing of review

The review time needs to be determined according to the specific situation [4].

Isolated solid nodules

For patients with only a single solid lung nodule and no risk factors for lung cancer:

Those ≤4 mm do not require follow-up, but should be aware of the potential benefits and harms of not following up.

Those with nodules 4 to 6 mm in diameter should be reassessed after 12 months and, if there is no change, converted to routine annual follow-up.

Nodules 6 to 8 mm should be followed up between 6 and 12 months, and if there is no change, they should be followed up again between 18 and 24 months, and then converted to routine annual follow-up.

＞Nodules >8 mm are followed up in a more complex manner and medical advice is recommended.

For patients with a single solid lung nodule with one or more risk factors for lung cancer:

Those ≤4 mm are followed up with imaging after 12 months, and if there is no change, they are converted to routine annual follow-up.

Those with nodules 4 to 6 mm in diameter should be followed up between 6 and 12 months, and if there is no change, they should be followed up again between 18 and 24 months, and then converted to routine annual follow-up.

Nodules 6 to 8 mm should be followed up between 3 and 6 months, then again between 9 and 12 months, and if there is no change, again within 24 months, and subsequently converted to annual routine follow-up.

＞Nodules >8 mm are more complex to follow up and medical advice is recommended.

Isolated sub-solid nodules

Pure ground-glass nodules ≤5 mm with one imaging follow-up at 6 months, followed by annual follow-up chest CT.

＞Pure ground-glass nodules >5 mm with imaging follow-up at 3 months, followed by routine annual follow-up if no change.

Partially solid nodules ≤8 mm, imaging follow-up once at 3, 6, 12, and 24 months, if no change. Switch to routine annual follow-up.

＞Partial solid nodules >8 mm, imaging follow-up once at 3 months, and if the nodule persists, thereafter further evaluation using PET, non-surgical biopsy or surgical resection is recommended.

Multiple pulmonary nodules

Recommended if at least 1 of the multiple pure ground-glass-like nodules has a lesion diameter of 5 to 10 millimeters and there are no particularly prominent lesions:

Follow-up CT 3 months after the initial examination.

If there is no change, CT follow-up once a year for at least 3 years thereafter.

Subsequent follow-up should also be long term, but the intervals can be relaxed appropriately.

If changes in the lesions are detected, the follow-up period should be adjusted according to the specific changes.

If the number of nodules is >10, it is called diffuse nodules and is generally considered to have a high likelihood of being accompanied by symptoms. It is mostly caused by metastasis of extrathoracic malignant tumors or active infection, and primary lung cancer is less likely.

Review program

Chest CT is the primary means of follow-up for lung nodules. It is recommended that the scanning protocol, scanning parameters, image display, reconstruction method and measurement method remain consistent for each examination.

Other tests and examinations are determined by the clinician according to the patient’s specific situation.

Prevention

Prevention of lung nodules should start with the cause of the disease, and different diseases are prevented in different ways. Although doing all of them will not completely prevent their occurrence, it will help to reduce the probability of disease and early detection.

Active treatment of the primary disease

For patients suffering from tuberculosis, pneumonia, chronic obstructive pulmonary disease, etc., they should be actively treated to control the progress of the disease.

Adopt a good lifestyle

Adhere to smoking and alcohol cessation.

People at risk of occupational exposure should take protective measures to avoid exposure to carcinogenic substances such as asbestos, chromium and nickel.

Avoid passive smoking, open-flame coal heating, and exposure to oil fumes.