Cancer Lung Cancer Causes & Risk Factors Possible Causes of a Lung Mass By Lynne Eldridge, MD Updated on November 09, 2023 Medically reviewed by Doru Paul, MD Print Table of Contents View All Table of Contents Definition What Can Cause a Mass in the Lung? What Are the Chances a Lung Mass Is Cancer? Diagnosis Treatment Symptoms of a mass in your lung can include shortness of breath, back pain or chest pain (especially when you breathe deeply or cough), and unexplained weight loss. Or, it's possible that your healthcare provider says you have a lung mass, but you've had no symptoms at all so far. Cancer is a likely reason, but benign tumors (not cancer), treatable infections, and other causes can lead to a lung mass. It's likely you'll see a pulmonary specialist (lung doctor) for more tests and diagnosis, an oncologist for cancer treatment, or other healthcare provider depending on the cause. This article discusses lung masses and their possible causes. It explains the tests commonly used to evaluate a lung mass and make a diagnosis, as well as some of the treatment options. Illustration by Brianna Gilmartin for Verywell Health Definition A lung mass is defined as an abnormal spot or area in the lungs larger than 3 centimeters (cm), about 1.5 inches, in size. Spots smaller than 3 cm in diameter are considered lung nodules. Size isn't the only factor, but it's a key determinant of whether a mass (or nodule) is a primary lung cancer. With respect to size: For nodules less than 5 millimeters, less than 1% are cancer.For nodules between 5 mm and 10 mm, there's up to a 28% chance that it's cancer.For nodules greater than 2 cm (approaching the size defined as a lung mass) the chance of malignancy is 64% to 82%. Malignant vs. Benign Tumors: What Are the Differences? What Can Cause a Mass in the Lung? The most common causes of a lung mass differ from those of a lung nodule. The chance that the abnormality may be malignant (cancerous) is lower for a lung nodule than it is for a mass. Cancer Size isn't the only factor, but it's a key determinant of whether a mass (or nodule) is a primary lung cancer. It's important to remember that age, smoking history, environmental exposure (such as radon or asbestos), and genetics all contribute to the chance of lung cancer. Diagnostic tests would determine the type of lung cancer. These types include: Non-small cell lung cancer, which accounts for 85% of lung cancers. It includes adenocarcinoma, squamous cell carcinoma, and large cell carcinomas. Small cell lung cancer, accounting for 10% to 15% of lung cancers Lung carcinoid tumors Metastases (spread) of cancers from other regions of the body to the lung are another cause. The most common cancers that spread to the lungs are breast cancer, colon cancer, and bladder cancer. Treatment options depend on the type and stage of the lung cancer. They can include surgery, radiation, chemotherapy, and immunotherapy drugs, with advances in recent years that have extended survival times. Lung cancer accounts for about 20% of cancer deaths and is currently the leading cause of cancer deaths in the United States. About 12% of all lung cancers occur in people who have never smoked, with increasing prevalence in younger people and those assigned female. Primary and Secondary Lung Cancer What Are the Chances a Lung Mass Is Cancer? If you have a lung mass, the most likely diagnosis is lung cancer. A history of smoking makes this even more likely. The risk also is higher among people with exposure to cancer-causing substances due to their occupation. For example, carpenters may have an elevated risk for cancers caused by wood dust. A lung mass is more concerning if it is described as “ground glass” on an imaging report. Calcifications and cavitary shapes are more likely with benign tumors. The key factors from imaging tests include not just size, but also: Change in size over time (likely benign if it stays stable over two years)The presence of calcification or fat (certain patterns are nearly always benign)The characteristic of the borders or edges (margins) of the mass The symptoms you experience, including a chronic cough, chest pain, blood-tinged sputum, and unexplained weight loss, all may suggest lung cancer. But they also are common with other lung diseases and it's important to seek a healthcare provider's accurate diagnosis. Signs and Symptoms of Lung Cancer Benign Causes Sometimes lung masses have noncancerous causes. These benign causes are not cancer, and they will not metastasize, but some can cause serious health complications and may need to be monitored over time and/or treated. Some benign causes of a lung mass include: Benign (noncancerous) lung tumors: Includes hamartoma, the most common type of benign lung tumor. People with an inherited disease known as Cowden syndrome have a greater risk for these growths. Lung abscesses: Infections that have been "walled off" and contained by the body AV malformations: Abnormal connection between arteries and veins that are usually present from birth Lipoid pneumonia Pulmonary artery aneurysms: An outpouching in the arteries that travel from the heart to the lungs can appear as a mass on imaging tests Amyloidosis: A build-up of abnormal proteins that form a mass Certain fungal infections and parasitic infections also can lead to lung masses. Diagnosis Your healthcare provider will take a careful history and do a physical examination as part of the assessment of your lung mass. Some of the questions your healthcare provider might ask include: Have you ever smoked? Have you traveled recently? What other medical conditions do you have? Do you have a family history of any medical problems, including lung cancer and other lung conditions? Have you been exposed to elevated radon levels in your home? (Radon is the second leading cause of lung cancer.) Are you having any symptoms, such as a persistent cough, coughing up blood, shortness of breath, lung pain, shoulder pain, back pain, or unexplained weight loss? Depending on the results of your history and physical exam, further tests might include imaging and/or a biopsy. Imaging If your healthcare provider noted a lung mass on your chest X-ray, they may recommend that you have computerized tomography (CT) or magnetic resonance imaging (MRI) scan to look at the mass more closely. These tests could help define the size and location of the mass, and sometimes make sure that the mass wasn’t an “artifact” on the X-ray—that is, something that looked like a mass but wasn’t, such as an overlap of tissues. A positron emission tomography (PET) scan is an imaging study that detects increased metabolic activity associated with active growth. For example, a suspicious area that does not light up on a PET scan may be old scar tissue whereas an area that lights up (shows signs of increased metabolism) is more likely to be a cancerous tumor. These tests can be especially helpful if a person has had radiation treatment for breast cancer, Hodgkin lymphoma, or lung cancer in the past—as radiation may cause scar tissue that resembles a tumor on an X-ray. They also play a key role in guiding current treatments. CT Scan vs. MRI Bronchoscopy If the mass is in the central area of the lungs near the large airways, a bronchoscopy may be recommended. During a bronchoscopy, healthcare providers pass a flexible tube through your mouth and down into your bronchi. This test can look for abnormalities in and near the large airways, and a biopsy can be performed if needed. An endobronchial ultrasound may also be done (an ultrasound that is done through the bronchi) during a bronchoscopy to better view abnormalities that are deep in the lungs and relatively close to the airways. What Is an Endobronchial Ultrasound? Fine Needle Biopsy If your lung mass is in the outer regions of the lungs, your healthcare provider may recommend a fine needle biopsy with a needle that is placed through the chest wall and into the mass to get a tissue sample. Types of Lung Biopsy Lung Surgery Sometimes it may be difficult to get a sample of the cells in your lung mass with either a needle biopsy or via a bronchoscopy. If this is the case, thoracic surgery may be recommended to get a sample of tissue. This may be done through small incisions and using instruments with a camera (video-assisted thoracoscopic surgery), or through a traditional incision to access the lungs (thoracotomy). The imaging and biopsy are done to provide information about the size, appearance, location, and cells in the mass. Thoracotomy: Everything You Need to Know Treatment The treatment of your lung mass will depend on the underlying cause. If it is a primary cancerous tumor of the lung or metastatic cancer from another region of the body to the lung, treatment options may include surgery, chemotherapy, or radiation therapy. Other less common causes of lung masses, such as infections, will be treated based on the diagnosis your healthcare provider determines after testing. Is Lung Cancer Curable? Treatment Options and Survival Rate Summary A mass in the lung can have a number of possible causes, not all of them cancer. Benign causes can include infection, aneurysm, or a congenital malformation, all with different treatment options and outlooks. But there is an increased concern for lung cancer with a lung mass, defined as an abnormal spot that's larger than 3 cm. The chance of malignancy is greater with size, but other factors (for example, the change in size over time) are important in making a diagnosis. Your healthcare team, including radiologists, cancer experts, and other specialists, will make the diagnosis on the basis of test results. Once a diagnosis is made, you can discuss treatment options. 8 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. RWJ Barnabas Health. Lung Mass. Radiology Key. Nodules and Masses. American Cancer Society. What Is Lung Cancer? American Cancer Society. Key Statistics for Lung Cancer. Siegel DA, Fedewa SA, Henley SJ, Pollack LA, Jemal A. Proportion of Never Smokers Among Men and Women With Lung Cancer in 7 US States. JAMA Oncol. 2021 Feb 1;7(2):302-304. doi:10.1001/jamaoncol.2020.6362. Hancock, D., Langley, M., Chia, K., Woodman, R., and E. Shanahan. Wood Dust Exposure and Lung Cancer Risk: A Meta-Analysis. Occupational and Environmental Medicine. 2015. 72(12):889-98. Gammon A, Jasperson K, Champine M. Genetic basis of Cowden syndrome and its implications for clinical practice and risk management. Appl Clin Genet. 2016;9:83–92. Published 2016 Jul 13. doi:10.2147/TACG.S41947 Kirienko M, Sollini M, Corbetta M, Voulaz E, Gozzi N, Interlenghi M, et al. Radiomics and gene expression profile to characterise the disease and predict outcome in patients with lung cancer. Eur J Nucl Med Mol Imaging. 2021 Oct;48(11):3643-3655. doi: 10.1007/s00259-021-05371-7. Additional Reading Kasper, DL.., Fauci AS, and Hauser, SL. Harrison's Principles of Internal Medicine. New York: Mc Graw Hill education, 2015. Print. Yao, Y., Lv, T., and Y. Song. How to Diagnose Pulmonary Nodules: From Screening to Therapy. Translational Lung Cancer Research. 2017. 6(1):3-5. By Lynne Eldridge, MD Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time." See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit