Hockeydad, we are still learning the answers to those questions. For us, the most important thing they are is what they are not, reoccurant or new cancer. My basic, beginning understanding is, scardodisis causes the granulomas, clumps. Sarcoidosis is an autoimmune disease, perhaps a reaction to the chemo in my husband's treatment. I don't know how common it is in cancer patients, other than to say of our 3 very experienced, top level docs at U of C, my husband is the first case they've seen. 90% of folks who have sarcoidosis live with relatively few symptoms, 10% really suffer. Again, we just started learning about it last Friday, after my the nodes in my husband's check and abdomen lit up hot (SUV 19) on a PET. Our big question now is, how will they be able to monitor him for mets if his chest lights up on PET?