The lungs are shaped like large, spongy, slightly concave cones on either side of the chest cavity. Made of multitudes of air sacs, they are lightweight and elastic. The right lung is larger than the left and has three lobes; the left lung has two lobes. When a chest X-ray or CT scan reveals a lesion, or spot, in the lungs, the findings may or may not pose a serious risk to health.
Granulomas
If the immune system cannot eliminate a foreign invader in the lungs, cells called macrophages may collect and form a granuloma, much like an oyster forms a pearl around a grain of sand. This "walling off" effect can keep infections dormant. Infectious granulomas are the most common reason for noncancerous lung spots, according to the National Institutes of Health. Granulomas may form following exposure to Mycobacterium tuberculosis, a contagious airborne bacteria, or Histoplasma capsulatum, a fungus found in soil, bird and bat droppings. In healthy persons, granulomas can fight infection. Active disease is more common in AIDS patients and others with compromised immune systems. Additionally, individuals who choke easily because of neurological problems may develop granulomas that contain food particles.
Noncancerous Tumors
Noncancerous, or benign, lung tumors usually appear as a round spot on a chest X-ray. Benign tumors usually cause no symptoms, but any mass needs to be evaluated and it can be difficult to determine if the lesion is cancerous. Risk factors such as age, smoking and the size or shape of the tumor help the doctor determine the best course of action. Options include observation, a biopsy, or surgery. A spot on the lung that has remained the same size for more than two years is thought to be benign. If surgery is necessary, only a small portion of lung tissue is removed. General anesthesia, drainage tubes, and a few days of hospitalization may be necessary.
According to the Pulmonary and Critical Care Associates of Baltimore, a hamartoma is the most common type of benign tumor, made up of cartilage, fat, and calcium. More rarely, a spot on the lung may be due to a hemangioma, or blood vessel tumor, or a lipoma, fatty tumor. Other possible tumors are leiomyomas that contains muscle cells or neurofibromas that consist of nerve tissue.
Lung Cancer
The American College of Chest Physicians released a guideline in 2007 stating that solitary pulmonary nodules, or lung spots, that have a "ground-glass" density, irregular borders, are larger than 8 cm. and double in size between one to 12 months are most likely malignant, or cancerous. According to the Centers for Disease Control and Prevention, more people die from lung cancer than from any other type of cancer. The two main types of cancer that originate in the lungs are small cell and non-small cell, distinguished by microscopic analysis. Treatments depend on the type of cancer and whether the malignancy has spread to other parts of the body.
