A “spot on the lung,” medically termed a pulmonary nodule, is a small, distinct growth or lesion found in the lung tissue. These findings are common and are often discovered incidentally when individuals undergo imaging tests, such as X-rays or CT scans, for unrelated health concerns. While concerning, most nodules are not cancerous. Medical evaluation is important to determine the nodule’s nature and next steps.
Understanding a Lung Nodule
A pulmonary nodule appears as a small, rounded or oval-shaped spot on imaging scans. A lung nodule typically measures less than 3 centimeters (approximately 1.2 inches) in diameter. Growths larger than this size are usually classified as lung masses, which tend to have a higher likelihood of being cancerous.
Nodules often cause no symptoms and are frequently unknown until detected through medical imaging. For instance, a nodule might be found during a CT scan performed for a headache, an abdominal issue, or after an accident. This highlights why medical evaluation is important, as many benign and malignant nodules can be asymptomatic.
Potential Causes of Lung Nodules
Lung nodules can arise from a variety of causes, broadly categorized as benign (non-cancerous) or malignant (cancerous). Benign nodules are far more common and often represent the body’s response to past infections or inflammation. Examples include granulomas, which are small clumps of inflamed cells that can form due to fungal infections like histoplasmosis or coccidioidomycosis, or bacterial infections such as tuberculosis. Inflammatory conditions, including sarcoidosis and rheumatoid arthritis, can also lead to the formation of non-infectious granulomas. Other benign causes include scar tissue from old injuries or infections, or benign tumors such as hamartomas.
In contrast, malignant nodules are a result of cancerous cell growth. These can be primary lung cancers, originating within the lung itself, or metastatic cancers, which have spread to the lung from another part of the body. Risk factors that increase the likelihood of a nodule being malignant include a history of smoking, older age, larger nodule size, and an irregular or spiculated (spiky) shape on imaging. The presence of multiple nodules can also increase concern for malignancy, especially if a person has a history of cancer.
Diagnostic Methods
Once a lung nodule is identified, healthcare providers use several methods to determine its nature. Imaging tests play a central role in this process. Follow-up CT scans are frequently used to monitor changes in the nodule’s size or appearance over time. Stable nodules that do not grow over a period are typically considered benign.
Positron Emission Tomography (PET) scans may be utilized to assess the metabolic activity within a nodule; higher activity can suggest a greater likelihood of malignancy. However, a PET scan alone cannot definitively diagnose cancer.
To obtain a definitive diagnosis, a biopsy is often necessary to collect tissue for microscopic examination. Different biopsy techniques are available depending on the nodule’s location and size. These include needle biopsies, where a needle is guided through the chest wall into the nodule (often with CT guidance), and bronchoscopic biopsies, where a flexible tube with a camera is inserted into the airways to reach the nodule. Surgical biopsies, such as video-assisted thoracic surgery (VATS), may be performed to remove a portion or the entire nodule for analysis.
Management and Follow-Up
The approach to managing a lung nodule depends on its characteristics, the individual’s risk factors, and the diagnostic findings. For small, stable, or clearly benign nodules, a strategy of watchful waiting and regular follow-up CT scans is often recommended. This monitoring allows healthcare providers to track the nodule for any changes in size or appearance that might indicate a need for further intervention. If a nodule remains unchanged over a specified period, typically two years, it is usually considered benign and further routine scans may not be needed.
If a nodule is determined to be malignant, treatment options are then considered based on the type and stage of the cancer. These options can include surgery to remove the cancerous tissue, radiation therapy, or chemotherapy. For benign conditions causing symptoms, specific treatment for that underlying condition would be pursued.