Livedo Reticularis

**Semantic type:** Finding

**Definition:** A recurrent purple discoloration of the skin that does not blanche and is found in a lacy, network pattern, most often in the lower extremities. It may be aggravated by exposure to cold and is classified as idiopathic or secondary. Secondary livedo reticularis may be a cutaneous manifestation of immune system disorders (e.g., lupus erythematosus, rheumatoid arthritis, cryoglobulinemia, lymphoma, etc), and hematologic disorders (polycythemia vera).