In sarcoidosis, the immune system starts to attack the body's own tissues, small lumps called granulomas. These are like small scars that interfere with the normal function of the organ attacked by the disease. Even after treatment, the scarring can remain and can continue to have some effect on organ function. For example, sarcoidosis of the eyes can cause blindness if not detected and treated promptly, and pulmonary sarcoidosis can cause permanent scarring that interferes with breathing during exercise even with treatment. The majority of people diagnosed with sarcoidosis lead relatively normal lives after diagnosis, with or without treatment, despite the lack of cure.