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A lung nodule is a small round to oval mass of tissue in the lung.
A lung nodule is a small round to oval mass of tissue in the lung. Nodules in the lung can be either cancerous (malignant) or noncancerous (benign). Most nodules less than 2 cm in diameter are benign. Benign lung nodules can have different causes. Many are caused due to inflammation in the lungs that may occur as a consequence of an infection or other diseases. The nodules may be the result of scar tissue formation related to prior inflammation. Some of the causes include
- Infections: Infections associated with pulmonary nodules include
- Mycobacterium tuberculosis
- Mycobacterium avium intracellular
- Aspergillosis
- Histoplasmosis
- Coccidiomycosis
- Cryptococcosis
- These infections result in inflammation, which further forms granuloma. A granuloma is a small cluster of cells that form when lung tissue is inflamed. It is formed when the immune system isolates any foreign substance in the lungs or other parts of the body. They can become calcified over time, as calcium tends to collect in the healing tissue.
- Noninfectious causes of benign inflammatory lung nodules: Other noninfectious disorders that may cause granuloma formation in the lungs include
- Tumor: Abnormal growth or mass in the lungs may be benign or malignant. Types of benign tumor include
- Hamartoma (an abnormal grouping of normal tissues such as fat, bones, muscles or cartilage in the lung)
- Neurofibroma (a lump made up of nerve tissue)
- Blastoma (a growth made up of immature cells)
- Fibroma (a lump of fibrous connective tissue)
- Adenomas (tumors arising from mucous gland)
- Types of malignant tumor include
- Lung cancer
- Lymphoma (a growth containing lymphoid tissue)
- Carcinoid (a small, slow-growing neuroendocrine cancerous tumor)
- Sarcoma (a tumor consisting of connective tissue)
- Metastatic tumors (tumors that have spread to the lungs from cancer in another part of the body)
- Congenital issues such as lung cyst or lung malformation
Should I worry that I have a nodule?
Most nodules aren’t cancer. However, for a small number of individuals, the nodule may turn out to be early cancer. A physician identifies and confirms the lung nodules as cancer by
- Checking how it looks on a computed tomography (CT) scan.
- Observing whether it grows over time. A nodule increasing in size over time may indicate lung cancer.
- Taking a biopsy of the nodule to confirm the cause. Most people with a nodule do not require a biopsy.
How is the cause of pulmonary nodules diagnosed?
If the physician suspects a pulmonary nodule, they will perform a physical examination and order tests to confirm the diagnosis. Some of the tests include
- Bronchoscopy, including advanced guided techniques such as
- endobronchial ultrasound (EBUS)
- electromagnetic navigational bronchoscopy (ENB)
- Chest?X-rays?(radiographs)
- Computed tomography?(CT) scan
- Fluoroscopy
- Image-guided sampling techniques that include CT-guided and ultrasound-guided biopsies (fine needle aspiration biopsy or FNA)
- Magnetic resonance imaging?(MRI)
- Minimally invasive lung biopsy (thoracoscopic or robotic)
- Positron emission tomography?(PET)
- Pulmonary function studies (PFT)
Depending on the features and size of the lung nodule on the CT scan, the physicians may also recommend
- Observing and repeating X-ray tests if the nodule is probably benign.
- Further imaging, such as a repeat CT scan of your chest or a PET scan.
- Taking a biopsy of the nodule via
- bronchoscopy (if the nodule is near one of your airways)
- a needle biopsy (if the nodule is located near the outside of your lungs)
- lung surgery (video-assisted thoracoscopic surgery) if the nodule seems to be cancerous