Lung Nodules: Symptoms, Causes, Diagnosis, and Treatment

Understanding what lung nodules are, how they are detected, managed, and when to seek treatment.

By Sneha Tete, Integrated MA, Certified Relationship Coach

Created on Sep 25, 2025

Understanding what lung nodules are, how they are detected, managed, and when to seek treatment.

Lung nodules — also called pulmonary nodules — are small masses or growths of tissue in the lungs. They are common findings on chest imaging and are usually not cancerous. This article explores lung nodules in detail, including their symptoms, causes, risk factors, diagnostic approaches, treatment options, prognosis, and answers to commonly asked questions.

Overview

A lung nodule is a round or oval mass of cells in the lungs that measures less than 30 millimeters (about 1.2 inches) in diameter. You can have a single nodule or multiple nodules, and more than 1.6 million Americans are diagnosed with lung nodules each year.
While most lung nodules are harmless, doctors monitor these growths due to a small risk of cancer, especially for larger nodules or those in high-risk groups.
At least 95% of lung nodules are not cancerous and are often detected incidentally during imaging performed for unrelated reasons. These nodules are found on about 0.1%–0.2% of chest X-rays and up to 13% of CT scans; these rates go as high as 9% of X-rays and 33% of CT scans in people at increased risk, such as smokers or those with a previous cancer diagnosis.
If a lung nodule is discovered, your doctor may monitor it over time to check for growth or changes. Treatment is typically only necessary if the nodule causes symptoms or demonstrates concerning features.

What is a Lung Nodule?

Lung nodules are small, rounded masses detected in lung tissue. They measure less than 30 mm (1.2 inches) in diameter. Nodules can be solitary or multiple and are detected with increasing frequency due to widespread use of advanced imaging like CT scans.
Only about 5% are cancerous, but monitoring is essential since nodules that increase in size are often malignant.
The risk of cancer increases with nodule size:

Smaller than 6 mm: Less than 1% chance of cancer
6–8 mm: 1%–2% chance of cancer
Larger than 8 mm: Over 2% chance of cancer

Doctors recommend regular CT surveillance for nodules between 6 and 8 mm. Larger nodules may require advanced imaging (PET/CT), biopsy, or surgical sampling.

Symptoms of Lung Nodules

Most lung nodules do not cause symptoms and are noticed only when a scan is performed for another reason. When symptoms are present, they’re often due to the underlying disease causing the nodule, such as an infection or inflammatory condition.
Symptoms that may occur include:

Cough
Shortness of breath
Wheezing or hoarseness
Chest pain (worsens with deep breathing, laughing, or coughing)
Coughing up blood or rust-colored phlegm
Back pain
Unexplained weight loss
Weakness or fatigue
Fever (if nodule is caused by an infection)

Causes and Risk Factors

Lung nodules may arise from various causes, both noncancerous and malignant:

Current lung infection: Tuberculosis, fungal infections, and bacterial pneumonia can produce nodules through localized inflammation and granuloma formation.
Past lung infections: Scarring from previous infections can leave behind benign nodules.
Noninfectious inflammation: Conditions like rheumatoid arthritis or sarcoidosis may trigger nodule development.
Noncancerous tumors: Benign tumors (such as pulmonary hematomas or hamartomas) can form nodules.
Lung cancer: Malignant nodules are possible, especially in high-risk groups.

Risk factors for malignant nodules:

Current or former smoking
Older age
Personal or family history of cancer
Chronic lung diseases (e.g., COPD)
Exposure to carcinogens: Asbestos, radon, diesel fumes, soot, arsenic, cadmium, or nickel
Immunosuppression

Diagnosis

Lung nodules are most often found incidentally on chest X-rays or CT scans performed for unrelated reasons. Nodules visible only on CT scans are often too small for X-ray detection.
The diagnostic process involves:

Reviewing previous imaging studies: Nodules that have not changed in size over time are less likely to be cancerous.
Analyzing nodule characteristics: Shape, size, growth rate, margins, and composition.
Advanced imaging: PET/CT scans for suspicious nodules, particularly those larger than 8 mm.
Biopsy: Sampling tissue from the nodule, typically if malignancy is suspected.
Surgical removal: Rarely, surgical excision is required, particularly for large or growing nodules.

The Fleischner Society provides widely used guidelines for managing lung nodules. These take into account:

Nodule size
Growth rate
Tissue composition

Note: The Fleischner guidelines generally exclude people under age 35, those with a history of cancer, or immunosuppressed individuals.

Lung Nodule Size Chart

**Risk of Cancer by Lung Nodule Diameter**
Diameter	Risk of Being Cancerous
1–2 mm	Very small risk
<6 mm	0% to 1%
6–8 mm	0.5% to 2%
>8 mm	About 9.7%
>10 mm	15.2%
>30 mm	Usually considered cancerous (lung mass)

Most nodules smaller than 10 mm are visible only on CT scan, not chest X-ray.

Treatment

Treatment decisions depend on nodule size, growth rate, and risk factors:

No treatment: Small, stable, painless nodules with low cancer risk are typically monitored with follow-up imaging.
Antibiotics: Used if an infection is suspected as the cause.
Removal of underlying cause: For autoimmune or inflammatory nodules, controlling the primary disease is key.
Surgical removal: Larger or growing nodules may be excised, especially if malignancy is a concern.
Biopsy or advanced diagnostics: For suspicious nodules or those in high-risk patients, tissue analysis may be needed.

If a nodule is malignant, prompt oncologic treatment will be necessary.

Outlook

The outlook for people with lung nodules is generally excellent, since most are not cancerous and never cause symptoms or medical problems.
Nodules are monitored over time, and if no growth or worrisome changes are seen, they are unlikely to be harmful. If cancer is detected, early diagnosis and intervention may significantly improve prognosis.

Small nodules carry less than 1% cancer risk
Large, growing, or irregular nodules demand closer attention
Timely follow-up and imaging are essential

Frequently Asked Questions

Q: Are most lung nodules cancerous?
A: No, about 95% are benign. Only a minority turn out to be malignant.
Q: Should all lung nodules be treated?
A: Most do not require treatment and are monitored for changes. Treatment is necessary if cancer or infection is suspected.
Q: How often will I need follow-up scans?
A: The frequency depends on size, risk factors, and doctor’s recommendations. Commonly, CT scans are repeated every 3–12 months.
Q: Can lung nodules cause symptoms?
A: Most are asymptomatic. Symptoms often reflect the underlying cause, not the nodule itself.
Q: What should I do if I have a lung nodule?
A: Follow your healthcare provider’s recommendations for monitoring and testing. Report any new respiratory symptoms promptly.
Q: What increases the risk that a lung nodule is malignant?
A: Smoking, older age, family history of cancer, exposure to carcinogens, and having chronic lung diseases.

Takeaway

Lung nodules are common findings on imaging studies. Almost all are benign, but doctors monitor their size and appearance closely due to a small risk of malignancy, particularly in high-risk populations. Early detection, appropriate surveillance, and timely intervention are key to optimal outcomes. If you have been diagnosed with a lung nodule, maintain regular follow-up with your doctor and discuss any concerns promptly.

References

Author

Sneha TeteBeauty & Lifestyle Writer

Sneha is a relationships and lifestyle writer with a strong foundation in applied linguistics and certified training in relationship coaching. She brings over five years of writing experience to thebridalbox, crafting thoughtful, research-driven content that empowers readers to build healthier relationships, boost emotional well-being, and embrace holistic living.

Read full bio of Sneha Tete