Sometimes chest x-rays and other imaging techniques identify multiple pulmonary nodules. These are lesions in the lungs with a multitude of possible causes. If the cause of these nodules is not already known, their presence on imaging indicates the need for further investigation, so that the disease or condition with which they are associated, can be properly treated.
Infection
According to a 2005 journal article in "Radiology," various infections can cause pulmonary nodules. Several types of fungal infections appear as pulmonary nodules on x-ray. Bacterial infections in the blood can cause abscesses in the lung. An abscess is a collection of bacteria, immune cells and debris that has been walled off by the body. Parasites such a paragonimus, which is a worm found most often in Asian countries, is also an infectious source of pulmonary nodules. Tuberculosis can also cause multiple nodules.
Tumors
Cancer, particularly metastatic cancer, is a source of multiple pulmonary nodules, according to a 2007 article in the medical journal "Chest." Metastatic cancer is cancer that develops at one site, and then spreads through the blood or lymphatic system to other sites in the body. Larger nodules, over 0.5 com, are more likely to be cancer than those under 0.5 cm. Pulmonary nodules may also be benign tumors, such as a hamartoma, which is a benign, disorganized growth of normal tissue.
Inflammation
Inflammatory conditions can increase the size of lymph nodes in and around the lungs, which can appear as nodules on imaging. For example, rheumatoid arthritis causes rheumatoid nodules in different areas of the body including the lungs. Another such condition is called Wegener's granulomatosis. This is a disorder causing inflammation of the blood vessels that affects the kidneys, lungs, and upper airway. It causes inflammatory tissues, called granulomas, to grow in and around the blood vessels. The granulomas can appear as multiple pulmonary nodules. Sarcoidosis is a similar condition, but is not limited to the kidneys and pulmonary system.
Pneumoconiosis
Pneumoconiosis, also called occupational lung disease, describes a lung disease caused by the inhalation of dust, such as in mines or factories. Silica and coal are both known offenders that cause multiple pulmonary nodules and scar tissues that interfere with the normal mechanics of breathing.
References
- "Radiology"; Guidelines for Management of Small Pulmonary Nodules Detected on CT Scans: A Statement from the Fleischner Society; MacMahon et al.; November 2005
- "Chest"; Evaluation of Patients With Pulmonary Nodules: When Is It Lung Cancer?; Gould et al; Sept 2007
