Participating in this study will require that blood and bone marrow samples be obtained as a part of the diagnostic work-up or follow-up of your multiple myeloma. Bone marrow/peripheral blood/tissue samples will be collected for research purposes, as well as testing for genetic traits of Castleman's disease if you consent to this study. In addition, data will be collected including demographic information gathered from your medical record, including gender, date of birth, ethnicity, date of diagnosis, laboratory and pathology results, treatment protocols, dates of relapses, subsequent treatment protocols, and current treatments and medications.