What Causes an X-Ray to Show Ring-Like Spots on the Lungs of a Nonsmoker?

Infections, disorders, neoplasms and tumors cause ring-like spots, known as pulmonary nodules or coin lesions, on the lungs of smokers and nonsmokers, states Cleveland Clinic. Ring-like spots that are larger than 3 centimeters in diameter are called pulmonary masses and are more likely to be cancerous.

Pulmonary nodules are caused by infections from conditions such as tuberculosis or Mycobacterium avium intracellulare, as well as fungal infections such as coccidioidomycosis and cryptococcosis, states Cleveland Clinic. Ring-like pulmonary nodules that appear on X-rays may be granulomas, which occur when the immune system isolates foreign substances in the lungs, forming clumps of cells. Rheumatoid arthritis and other noninfectious disorders also cause pulmonary nodules in nonsmokers.

Pulmonary nodules may also be neoplasms, which are benign or malignant abnormal growths such as lumps of connective tissues called fibromas, or lumps of nerve tissues known as neurofibromas, according to Cleveland Clinic. These conditions can occur in nonsmokers, as can malignant lung tumors such as cancer, lymphoma, carcinoids, sarcomas and metastatic tumors. Secondhand smoke and exposure to carcinogens such as sulfur oxide-related pollution may cause pulmonary nodules and masses that are cancerous in the lungs of nonsmokers. The risk of developing pulmonary nodules and masses increases with age and if there is a family history of pulmonary disease.