Sarcoidosis is an illness that occurs in people with low immunity. It leads to tiny lumps (called granulomas) developing in and on your body. Acute sarcoidosis is also called Lofgren's syndrome and can flare up quickly. It causes enlarged lymph glands in the chest, large and very tender purple lumps on the shins, fevers, weakness and joint pains. In most cases it goes away without treatment. Chronic sarcoidosis causes scarring (fibrosis) of the lungs that gets worse over time. It can also cause very bad skin rashes and can affect other body organs including the heart and brain.