Sarcoidosis is an autoimmune disease. Cause unknown. Can attack any organ. This disease can be very debilitating and in my case will most likely be the cause of my death. It is in my lungs, spleen, liver and the joints in my hands. This disease is no joke. Believe me, sometimes when my old friend plays with my body the thoughts of suicide are very real. You may want to read my introduction "Brought down by a bug."