Lung mass
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Resident Survival Guide |
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Lung Mass Microchapters |
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Diagnosis |
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Treatment |
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Lung mass On the Web |
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American Roentgen Ray Society Images of Lung mass |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Maria Fernanda Villarreal, M.D. [2] Akshun Kalia M.B.B.S.[3]
Synonyms and keywords:Pulmonary mass
Overview
Lung mass (also known as "Pulmonary mass") is defined as any area of pulmonary opacification that measures more than 30 mm (3 cms) in size. Lung mass is an abnormal growth found in the lung which can be either be benign or malignant. The first reported case of lung mass dates back to the early 1400s when approximately 50% of the miners in Germany and Czech Republic died of a pulmonary disease called "Bergkrankheit". In 1929, a German physician, Fritz Lickint, published a paper and suggested that lung mass patients were likely to be smokers and launched anti tobacco campaign in Germany. In 1950's, American physicians, Cuyler Hammond and Ernest Wynder provided additional corroboration for a causal association between smoking and lung cancer. In 1969, the first surgeon general warning was issued suggesting cigarette smoking to be a hazard for lung cancer. Lung mass can be classified into malignant and benign. In addition, lung mass can be sub-classified according to location, imaging features, and distribution. The most common cause of a lung mass is lung cancer. Other common causes of lung mass include hamartoma, Hodgkin's lymphoma, granuloma, lipoma, tuberculosis, and aspergillosis. It is thought that lung mass is the result of genetic and environmental factors. Genetic mutation leads to uncontrolled cell proliferation which predispose to tumorigenesis. Genes involved in the pathogenesis of lung mass include mutations in K-ras oncogene and TP53 tumor-suppressor gene. Other genes include mutation in EML4-ALK, PIK3CA, c-MET, NKX2-1, LKB1 and BRAF kinase. Environmental factors include smoking (most important carcinogen), radon, asbestos, viral infections, and states of chronic lung inflammation, all of which may predispose to cellular damage and DNA mutations that may further lead to development of lung mass. Lung mass can be differentiated from other conditions that cause chronic cough, hemoptysis, and weight loss based on the clinical features, laboratory findings, imaging features, histological features, and genetic studies. The incidence rate of lung mass is approximately 58 per 100 000 individuals in the United States. The incidence of lung mass increases with age; the median age at diagnosis is between 25 to 70 years. The prevalence of malignancy among lung mass ranges between 200 - 50,000 per 100,000 cases worldwide (or from 0.2% to 50%). Males are more commonly affected with lung mass than females. The male to female ratio is approximately 2 to 1. There is no racial predilection for lung mass. Risk factors for developing a lung mass include exposure to different chemicals and compounds in the workplace or the environment in general. Active and passive tobacco smoking also increases the risk of developing lung mass and so does the personal and family history of a lung mass. According to the U.S. Preventive Services Task Force (USPSTF), screening for suspected lung cancer by low-dose computed tomography is recommended every year among smokers who are between 55 to 80 years old and who have a history of 30 pack-years or more and either continue to smoke or have quit within the past 15 years (grade B recommendation). A hallmark feature in the evaluation of lung mass is the malignancy assessment. The evaluation approach of lung mass will mainly depend on the initial morphological evaluation of the mass (size, margins, contours, calcification pattern, and growth). Other characteristics, such as location, clinical features, and distribution, may be helpful for the therapeutic management, surveillance, and follow-up of lung mass. Lung mass can be divided into 2 categories: benign pulmonary mass and malignant lung mass. Based upon these categories, complementary diagnostic studies and management, include: PET/CT scan, CT scan, non-surgical biopsy, and surgical resection. Lung biopsy is the gold standard test for the diagnosis of lung mass. However, in order to determine the extent of invasion and to derive therapy, other investigative modalities such as CT scan, sputum cytology and PET scan are also necessary. According to the American Joint Committee on Cancer (AJCC) staging system, there are 4 stages of malignant lung mass based on 3 factors: tumor size, lymph node invasion, and metastasis. Each stage is assigned a letter and a number that designate T for tumor size, N for node invasion, and M for metastasis. The hallmark symptoms of lung mass include chronic cough, weight loss, and hemoptysis. A positive history of smoking, exposure to asbestos, tuberculosis infection, or a high risk occupation may be suggestive of a lung mass. Symptoms related to lung mass will vary depending upon the size and location of tumor. Common symptoms of lung mass may also include shortness of breath, fatigue, and chest pain. Physical examination findings of lung mass will depend on the location of the tumor. Lung mass with central location may cause crackling sounds, focal wheezing, voice hoarseness, and tachypnea. Lung mass with peripheral location can present with pleurisy findings, such as reduced chest expansion. Common physical examination findings of patients with lung mass include crackling or bubbling noises, decreased/absent breath sounds, and positive findings on whispered pectoriloquy. Laboratory findings associated with lung mass varies with the underlying presentation. The findings may range from normal to severely elevated. In general, a thorough laboratory evaluation is necessary to accurately assess, diagnose and stage the severity of lung mass. Laboratory evaluations include complete blood count, electrolytes, serum calcium, alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, serum creatinine, albumin, and lactate dehydrogenase. There are no specific ECG findings associated with lung mass. However, lung cancer may metastasize to heart through the lymphatic/hematogenous route or via direct invasion. The most commonly involved part of the heart is the pericardium followed by myocardium and finally endocardium. On an ECG, patient of lung mass with cardiac metastasis may present with nonspecific T wave and ST segment changes. An x-ray may be helpful in the diagnosis of lung mass. Findings on an x-ray suggestive of lung mass include rounded or spiculated mass, bulky hilum, and lobar collapse. Echocardiography can help in the diagnosis making of a lung mass. Transesophageal echocardiography (TEE) can successfully determine the extent of invasion of a lung mass into the great vessels. Endobronchial ultrasound can be used as the initial diagnostic and staging procedure. CT scan is the method of choice for the evaluation of lung mass. On CT scan, characteristic findings of lung mass include single pulmonary nodule or mass with localized area of parenchymal consolidation and bubble-like areas of low attenuation within the lung mass (characteristic finding). There are no characteristic MRI findings associated with lung mass. However, an MRI may be helpful in the assessment of mediastinal lymph nodes and in the diagnosis distant metastasis (malignant lung mass). Positron emission tomography (PET) scan and bone scan can be performed to aide in the diagnosis making and also to keep an eye on the progression of the tumor and the response to therapy. Biopsy of a lung mass may be classified into 2 categories: non-surgical biopsy and surgical biopsy. Biopsy findings associated with lung mass will depend on tumor histology. Common types of lung tissue biopsy for lung mass include conventional bronchoscopic-guided transbronchial biopsy, bronchoscopic-transbronchial needle aspiration, endobronchial ultrasound-guided sheath transbronchial biopsy, and endobronchial ultrasound-guided transbronchial needle aspiration. Common indications for biopsy in lung mass include suspected lung cancer and malignant features (lymph node involvement). Medical therapy for patients with lung mass vary and depends upon the underlying cause. The course and type of medical therapy to be administered is decided after the diagnosis has been established. Masses of benign nature are almost always left untreated but are followed up on regular basis according to the set criteria and guideline. Masses that exhibit continuous growth are aggressively addressed and managed. Surgical excision is the mainstay therapy for malignant lung mass. Surgical excision is also the primary choice for the definitive diagnosis making of malignant lung mass. The surgical procedure selection will depend on the size, margins, and size of the mass. Effective measures for the primary prevention of lung mass include smoking cessation and avoidance of second hand smoking. In general, lifestyle changes with diet rich in vitamins and antioxidants, such as healthy diet rich in fruits and vegetables and regular exercise, may decrease the risk of tumorigenesis and malignancy. The secondary prevention of lung mass includes regular follow-up.
Historical Perspective
The first reported case of lung mass dates back to the early 1400s when approximately 50% of the miners in Germany and Czech Republic died of a pulmonary disease called "Bergkrankheit". In 1929, a German physician, Fritz Lickint, published a paper and suggested that lung mass patients were likely to be smokers and launched anti tobacco campaign in Germany. In 1950's, American physicians, Cuyler Hammond and Ernest Wynder provided additional corroboration for a causal association between smoking and lung cancer. In 1969, the first surgeon general warning was issued suggesting cigarette smoking to be a hazard for lung cancer.
Classification
Lung mass can be classified into malignant and benign. In addition, lung mass can be sub-classified according to location, imaging features, and distribution.
| Lung mass | |||||||||||||||||||||||||||||||||||
| Location | Histology | Imaging Features | |||||||||||||||||||||||||||||||||
| •Pleural •Endobronchial •Parenchymal | •Malignant mass •Benign mass | •Hyperdense pulmonary mass •Cavitating pulmonary mass | |||||||||||||||||||||||||||||||||
Causes
The most common cause of a lung mass is lung cancer. Other common causes of lung mass include hamartoma, Hodgkin's lymphoma, granuloma, lipoma, tuberculosis, and aspergillosis.
Pathophysiology
It is thought that lung mass is the result of genetic and environmental factors. Genetic mutation leads to uncontrolled cell proliferation which predispose to tumorigenesis. Genes involved in the pathogenesis of lung mass include mutations in K-ras oncogene and TP53 tumor-suppressor gene. Other genes include mutation in EML4-ALK, PIK3CA, c-MET, NKX2-1, LKB1 and BRAF kinase. Environmental factors include smoking (most important carcinogen), radon, asbestos, viral infections, and states of chronic lung inflammation, all of which may predispose to cellular damage and DNA mutations that may further lead to development of lung mass.
Differential Diagnosis
Lung mass can be differentiated from other conditions that cause chronic cough, hemoptysis, and weight loss based on the clinical features, laboratory findings, imaging features, histological features, and genetic studies.
Epidemiology and Demographics
The incidence rate of lung mass is approximately 58 per 100 000 individuals in the United States. The incidence of lung mass increases with age; the median age at diagnosis is between 25 to 70 years. The prevalence of malignancy among lung mass ranges between 200 - 50,000 per 100,000 cases worldwide (or from 0.2% to 50%). Males are more commonly affected with lung mass than females. The male to female ratio is approximately 2 to 1. There is no racial predilection for lung mass.
Risk Factors
Risk factors for developing a lung mass include exposure to different chemicals and compounds in the workplace or the environment in general. Active and passive tobacco smoking also increases the risk of developing lung mass and so does the personal and family history of a lung mass.
Screening
According to the U.S. Preventive Services Task Force (USPSTF), screening for suspected lung cancer by low-dose computed tomography is recommended every year among smokers who are between 55 to 80 years old and who have a history of 30 pack-years or more and either continue to smoke or have quit within the past 15 years (grade B recommendation).
Diagnosis
Evaluation of Lung Mass
A hallmark feature in the evaluation of lung mass is the malignancy assessment. The evaluation approach of lung mass will mainly depend on the initial morphological evaluation of the mass (size, margins, contours, calcification pattern, and growth). Other characteristics, such as location, clinical features, and distribution, may be helpful for the therapeutic management, surveillance, and follow-up of lung mass. Lung mass can be divided into 2 categories: benign pulmonary mass and malignant lung mass. Based upon these categories, complementary diagnostic studies and management, include: PET/CT scan, CT scan, non-surgical biopsy, and surgical resection.
Chest X ray (CXR) shows opacity | |||||||||||||||||||||||||||||||||
More than > 30 mm | Less than <30 mm | ||||||||||||||||||||||||||||||||
Multiple | Single (or solitary) | ||||||||||||||||||||||||||||||||
For complete algorithm on evaluation of lung mass please click here
Diagnostic Study of Choice
Lung biopsy is the gold standard test for the diagnosis of lung mass. However, in order to determine the extent of invasion and to derive therapy, other investigative modalities such as CT scan, sputum cytology and PET scan are also necessary. According to the American Joint Committee on Cancer (AJCC) staging system, there are 4 stages of malignant lung mass based on 3 factors: tumor size, lymph node invasion, and metastasis. Each stage is assigned a letter and a number that designate T for tumor size, N for node invasion, and M for metastasis.
History and Symptoms
The hallmark symptoms of lung mass include chronic cough, weight loss, and hemoptysis. A positive history of smoking, exposure to asbestos, tuberculosis infection, or a high risk occupation may be suggestive of a lung mass. Symptoms related to lung mass will vary depending upon the size and location of tumor. Common symptoms of lung mass may also include shortness of breath, fatigue, and chest pain.
Physical Examination
Physical examination findings of lung mass will depend on the location of the tumor. Lung mass with central location may cause crackling sounds, focal wheezing, voice hoarseness, and tachypnea. Lung mass with peripheral location can present with pleurisy findings, such as reduced chest expansion. Common physical examination findings of patients with lung mass include crackling or bubbling noises, decreased/absent breath sounds, and positive findings on whispered pectoriloquy.
Laboratory Studies
Laboratory findings associated with lung mass varies with the underlying presentation. The findings may range from normal to severely elevated. In general, a thorough laboratory evaluation is necessary to accurately assess, diagnose and stage the severity of lung mass. Laboratory evaluations include complete blood count, electrolytes, serum calcium, alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, serum creatinine, albumin, and lactate dehydrogenase.
Electrocardiogram
There are no specific ECG findings associated with lung mass. However, lung cancer may metastasize to heart through the lymphatic/hematogenous route or via direct invasion. The most commonly involved part of the heart is the pericardium followed by myocardium and finally endocardium. On an ECG, patient of lung mass with cardiac metastasis may present with nonspecific T wave and ST segment changes.
X-ray
An x-ray may be helpful in the diagnosis of lung mass. Findings on an x-ray suggestive of lung mass include rounded or spiculated mass, bulky hilum, and lobar collapse.
Echocardiography and Ultrasound
Echocardiography can help in the diagnosis making of a lung mass. Transesophageal echocardiography (TEE) can successfully determine the extent of invasion of a lung mass into the great vessels. Endobronchial ultrasound can be used as the initial diagnostic and staging procedure.
CT scan
CT scan is the method of choice for the evaluation of lung mass. On CT scan, characteristic findings of lung mass include single pulmonary nodule or mass with localized area of parenchymal consolidation and bubble-like areas of low attenuation within the lung mass (characteristic finding).
MRI
There are no characteristic MRI findings associated with lung mass. However, an MRI may be helpful in the assessment of mediastinal lymph nodes and in the diagnosis distant metastasis (malignant lung mass).
Other Imaging Findings
Positron emission tomography (PET) scan and bone scan can be performed to aide in the diagnosis making and also to keep an eye on the progression of the tumor and the response to therapy.
Other Diagnostic Studies
Biopsy of a lung mass may be classified into 2 categories: non-surgical biopsy and surgical biopsy. Biopsy findings associated with lung mass will depend on tumor histology. Common types of lung tissue biopsy for lung mass include conventional bronchoscopic-guided transbronchial biopsy, bronchoscopic-transbronchial needle aspiration, endobronchial ultrasound-guided sheath transbronchial biopsy, and endobronchial ultrasound-guided transbronchial needle aspiration. Common indications for biopsy in lung mass include suspected lung cancer and malignant features (lymph node involvement).
Treatment
Medical Therapy
Medical therapy for patients with lung mass vary and depends upon the underlying cause. The course and type of medical therapy to be administered is decided after the diagnosis has been established. Masses of benign nature are almost always left untreated but are followed up on regular basis according to the set criteria and guideline. Masses that exhibit continuous growth are aggressively addressed and managed.
Surgery
Surgical excision is the mainstay therapy for malignant lung mass. Surgical excision is also the primary choice for the definitive diagnosis making of malignant lung mass. The surgical procedure selection will depend on the size, margins, and size of the mass.
Primary Prevention
Effective measures for the primary prevention of lung mass include smoking cessation and avoidance of second hand smoking. In general, lifestyle changes with diet rich in vitamins and antioxidants, such as healthy diet rich in fruits and vegetables and regular exercise, may decrease the risk of tumorigenesis and malignancy.
Secondary Prevention
The secondary prevention of lung mass includes regular follow-up.