Tissue necrosis caused by distal capillary thrombosis resulting from cryoglobulin precipitation in the vessels. The black tissue under the nails is ischemic, and will eventually slough, or be reabsorbed by the body.
Review Date 1/25/2023
Updated by: Neil J. Gonter, MD, Assistant Professor of Medicine, Columbia University, NY and private practice specializing in Rheumatology at Rheumatology Associates of North Jersey, Teaneck, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.