A “spot on the lung,” formally known as a pulmonary nodule, is a small, round or oval growth of dense tissue found on lung imaging tests. These spots are common and typically less than 3 centimeters (about 1.2 inches) in diameter. While their discovery can cause concern, most lung nodules are benign.
How Lung Spots Are Found
Lung nodules are often discovered incidentally, found by chance during imaging tests performed for unrelated medical reasons. A chest X-ray or CT scan ordered for symptoms like chest pain, an injury, or another health condition might reveal a nodule. These incidental findings are quite common.
Beyond incidental discoveries, lung spots can also be identified through targeted screening programs, particularly for individuals at high risk for lung cancer. Low-dose CT scans are used in these screenings to detect nodules, allowing for early detection. The majority of nodules detected, even in high-risk groups, are not cancerous.
Understanding the Causes
Lung nodules stem from various factors, most being non-cancerous. One common cause is past or current infections, which can leave behind scar tissue or clusters of immune cells called granulomas. Examples include fungal infections like histoplasmosis or coccidioidomycosis, and bacterial infections such as tuberculosis or pneumonia. These infections can cause inflammation, leading to the formation of these small growths.
Inflammatory conditions also contribute to benign nodules. Diseases like rheumatoid arthritis or sarcoidosis, an inflammatory condition that can form granulomas in various organs including the lungs, are known causes. Scarring from previous lung injuries or other inflammatory processes can also appear as nodules on scans. Additionally, benign tumors, such as hamartomas, which are common non-cancerous growths made of normal tissue components like cartilage or fat, can present as lung nodules.
While less common, a lung spot can sometimes indicate a more serious condition, such as lung cancer. These malignant nodules can originate in the lung or represent cancer that has spread from another part of the body. Factors like older age, a history of smoking, a family history of cancer, or exposure to certain environmental toxins like asbestos or radon can increase the likelihood of a nodule being cancerous.
Evaluating a Lung Spot
Once a lung spot is identified, medical professionals undertake a thorough evaluation to determine its nature. The initial assessment involves reviewing the patient’s medical history, including risk factors such as smoking status, age, previous cancers, or environmental exposure. Doctors also consider the nodule’s characteristics on imaging, such as its size, shape, and calcifications. Nodules that are small, slow-growing, and have a smooth, round shape are more likely to be benign.
Follow-up imaging with CT scans is a common step, particularly for smaller or indeterminate nodules. These scans help monitor any changes in the nodule’s size or appearance over time. If a nodule remains stable in size for at least two years, it is generally considered benign, as cancerous nodules tend to grow more rapidly.
Further evaluation may involve advanced imaging techniques like positron emission tomography (PET) scans. PET scans can help differentiate between benign and malignant nodules by detecting metabolic activity; cancerous cells often show higher metabolic rates. However, some inflammatory or infectious nodules can also show increased metabolic activity, so a PET scan alone cannot definitively diagnose cancer.
In situations where a nodule is highly suspicious due to its size, appearance, or a patient’s risk factors, a biopsy may be performed. This procedure involves obtaining a tissue sample from the nodule for microscopic examination to determine if cancer cells are present. Biopsies can be done using various methods, such as a needle guided by imaging or through a bronchoscope, a thin tube inserted into the airways.
What Happens After Evaluation
Following the evaluation, the management strategy for a lung spot depends on the findings. For nodules determined to be benign or highly likely benign, regular monitoring with follow-up CT scans is often recommended. This “watchful waiting” approach ensures that the nodule remains stable and does not exhibit any concerning changes over time. The frequency of these scans can vary based on the nodule’s characteristics and the patient’s risk profile.
If a specific benign cause, such as an infection, is identified, treatment for that underlying condition may be initiated. For example, a localized lung infection might be treated with antibiotics, followed by a repeat CT scan to confirm resolution. Benign nodules typically do not require active treatment unless they cause symptoms or grow to a size that interferes with lung function.
If the evaluation confirms that the spot is cancerous, various treatment options will be discussed. These options can include surgery to remove the nodule, radiation therapy, or chemotherapy. The specific treatment plan depends on the type of cancer, its stage, and whether it has spread beyond the lung. Early detection of lung cancer, even as a small nodule, can significantly improve treatment outcomes.