Cryoglobulinemia is caused by an abnormal protein that is occasionally found in the blood of people with multiple myeloma, leukemia, and certain forms of pneumonia. It causes blood to gel at low temperatures. In this picture, cryoglobulinemia has reduced blood flow in the fingers so much the fingers have turned dark; the black areas are gangrene resulting from lack of blood flow.
Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Blackman, Stephanie Slon, and Nissi Wang.