Sarcoidosis can attack any part of the body—inside or out. It appears as small patches of inflamed cells. Sarcoidosis usually goes away on its own, disappearing without the patient or doctor necessarily noticing it.
When sarcoidosis appears in the lungs it is called "pulmonary sarcoidosis". In pulmonary sarcoidosis, small patches of inflamed cells can appear on the lungs' small air sacs (alveoli), breathing tubes (bronchioles) or lymph nodes. In serious cases of pulmonary sarcoidosis, it can lead to an abnormal formation of scar tissue in the lung, called pulmonary fibrosis. The scar tissue warps the structure of the lung, which can make breathing difficult. It also affects the lungs' ability to move oxygen into the bloodstream.
Ninety percent of cases affect the lungs. Other common sites include: skin, liver, lymph glands, spleen, eyes, nervous system, including the brain, muscles and bones (musculoskeletal system), heart, and kidneys.