Definition

A tumor is an abnormal tissue growth that occurs when cells divide too rapidly or experience abnormal cell death. A lung tumor is a tumor that grows in the lung tissue or the airways leading to the lungs. It is a relatively common condition, found in 1 out of 500 chest X-rays and 1 out of 100 chest CT scans. A lung tumor can be benign or malignant (cancerous), but most lung tumors are benign. Benign and malignant tumors can be distinguished by their characteristics. Here are the characteristics of benign tumors:

• Do not spread to other parts of the body, unlike cancer.
• Growth slowly or may even stop growing and shrink on their own.
• Usually not life-threatening.
• Usually do not need to be removed unless they are large and cause symptoms.
• Can grow and press on surrounding tissues but does not invade or damage those tissues.

Lumps larger than 3 cm are usually called tumors, while those 3 cm or smaller are called nodules. If the nodule is in the lung, it is specifically called a lung nodule. These lung nodules are typically surrounded by normal lung tissue and can be solitary or multiple. Benign types of lung tumors or nodules include:

• Hamartoma: This is the most common benign lung tumor and the third most common cause of a solitary lung nodule. This type accounts for 55% of all benign lung tumors and 8% of all lung tumors. At least 80% are found on the outer parts of the lung, with the remainder growing in the airways leading to the lung. Hamartomas consist of normal tissues like cartilage, connective tissue, fat, and muscle, but in abnormal quantities. They usually measure less than 4 cm and can be seen on chest X-rays. Hamartomas generally grow in a limited area and do not compress surrounding structures. They are more common in men than women and occur most frequently in individuals aged 50-70.
• Bronchial adenoma: Another type of benign lung nodule that grows in the large airways (bronchi) and the mucus glands or their ducts in the throat.
• Papilloma: A rare type of benign lung tumor that grows on the surface of the airways, making it protrude outward.

Other rare types of lung tumors consist of connective or fatty tissue, including chondroma, fibroma, neurofibroma, and lipoma.

Causes

The exact causes of benign lung tumors and nodules are not well understood. Many potential causes are thought to contribute to their growth, including:

• Granulomas (clusters of inflammatory cells) formed due to bacterial infections in the lungs, such as tuberculosis (lung spots or wet lungs) or fungal infections in the lungs (histoplasmosis, cryptococcosis, aspergillosis, etc.)
• Lung abscesses (pus-filled pockets caused by bacterial infection)
• Inflammation due to diseases such as rheumatoid arthritis, sarcoidosis, and Wegener's granulomatosis
• Human papillomavirus (HPV) infection
• Congenital abnormalities like lung cysts or other abnormal lung conditions
• Some lung tumors have no known cause.

Risk factor

Anyone can develop lung nodules or tumors. However, they are more likely to be cancerous if there are certain risk factors, such as:

• About half of smokers over 50 years old will have lung nodules on their CT scans and are at a higher risk of malignancy.
• Age over 65 years
• A family history of cancer
• Previous chest radiation therapy
• Exposure to asbestos, radon, or secondhand smoke

Symptoms

More than 90% of lung nodules are found incidentally during chest X-rays or CT scans performed for other reasons. Therefore, most benign lung tumors do not cause symptoms. If symptoms do occur, they may include:

• Persistent mild cough
• Shortness of breath, heavy breathing
• Wheezing when exhaling
• Coughing up blood
• Noisy breathing
• Fever, especially if accompanied by a lung infection

Diagnosis

To diagnose a tumor or nodule in the lung, your doctor will first gather your medical history and conduct a physical examination. The tumor or lung nodule will then be evaluated using chest X-rays or CT scans. If a tumor is found, the doctor may perform a bronchoscopy to directly view it more clearly. This procedure involves inserting a small tube with a camera into the throat and down into the lungs. You will be under anesthesia during this procedure. The doctor may also take a tissue sample (biopsy) during the bronchoscopy, and the sample will be examined in a laboratory to determine the exact type of tumor and whether it is benign or malignant. Another method to obtain a tissue sample is by using a needle inserted into the tumor, guided by CT scan, thus avoiding the need for a skin incision.

Additional information that can be used to diagnose the tumor includes:

• Tumor size: The doctor may note the growth rate of the tumor. Smaller tumors are more likely to be benign. Additionally, benign tumors grow slowly and sometimes do not grow at all, while malignant tumors can double in size every four months or less.
• Content, shape, and color of the tumor: Another way to distinguish benign from malignant tumors is to examine their calcium content. Benign tumors have higher calcium levels and are usually regular in shape and softer. The color of benign tumors is also more uniform. Malignant tumors have irregular shapes, rough surfaces, and varied colors.

Differentiating between a benign tumor and early-stage cancer is crucial because early detection and treatment of lung cancer can significantly improve survival rates.

Management

In most cases, lung tumors are benign and do not require specific treatment, but their growth should still be monitored by a doctor. The doctor will perform serial chest X-rays or CT scans over several months or years to check for changes in the size or characteristics of the tumor.

In certain cases, a biopsy or surgery to remove the tumor may be necessary, such as when:

• The patient is a smoker or has a high risk of cancer
• The tumor causes breathing difficulties or other symptoms
• Tests indicate that cancer may be present
• The tumor continues to grow

If your doctor has determined that your tumor only needs monitoring, you should follow up with regular check-ups. However, if you have had surgery to remove a benign tumor and it has been completely removed, no further treatment is typically needed.

Complications

Although rare, benign lung tumors can press against and obstruct the airways. If this happens and is not treated, it can cause breathing difficulties and, in severe cases, respiratory failure. If this occurs, you may need surgery to remove the tumor.

Prevention

Quitting smoking is the best thing you can do to protect your lungs. If you do not smoke, you should also avoid exposure to asbestos, vehicle pollutants, and secondhand smoke. Other than this, there are no specific steps to prevent the occurrence of lung tumors.

When to see a doctor?

You should consult a doctor if:

• You experience changes in your cough pattern, such as increased severity or coughing up blood
• You experience shortness of breath, fever, chills, or chest pain
• You experience unintentional weight loss