The differential diagnosis for a patient with
purpuric/necrotic skin lesions should be broad and include vasculitis (eg, inflammatory, antineutrophil cytoplasmic antibody positive, septic), hypercoagulopathy (eg, antiphospholipid syndrome, antithrombin III, prothrombin mutation G20210A,
factor V Leiden, protein C, protein S), drugs
(eg, heparin, warfarin, cocaine with or without levamisole, intravenous drug use, hydroxyurea, ergotamine, propylthiouracil10), calciphylaxis,
cold-induced thrombosis, emboli (eg, atheroma, cholesterol, endocarditis, myxoma, aortic angiosarcoma, marantic), febrile ulceronecrotic Mucha-Habermann disease, infection especially if immunosuppressed (eg, disseminated Acanthamoeba/Candida/histoplasmosis/strongyloides/varicella-zoster virus,
S aureus, streptococcus, ecthyma gangrenosum, gas gangrene, hemorrhagic smallpox, lues maligna with human immunodeficiency virus, Meleney ulcer, Rocky Mountain spotted fever, Vibrio vulnificus), idiopathic thrombocytopenic purpura, thrombotic thrombocytopenic purpura, thrombocythemia, Waldenström hyperglobulinemic purpura, pyoderma gangrenosum, cancer (eg, paraneoplastic arterial thrombi), oxalosis, paraproteinemia (eg, multiple myeloma), and lupus with generalized coagulopathy. Less likely diagnoses might include Degos disease, factitial dermatitis, foreign bodies, multiple spider bites, paroxysmal nocturnal hemoglobinuria, sickle cell anemia, Buruli ulcer, or thromboangiitis obliterans. Branched, angulated, retiform lesions are an important finding, and some of these diagnostic possibilities are not classically retiform. However, clinical findings are not always classical, and astute physicians want to be circumspect. Had more ominous findings been present in our patient (eg, fever, hemodynamic instability, progressive skin lesions, systemic organ involvement), prompt hospitalization and additional considerations would have been necessary, such as septicemia (eg, meningococcemia, bubonic plague [Black Death], necrotizing
fasciitis, purpura fulminans), catastrophic antiphospholipid syndrome, or disseminated intra-
vascular coagulation.
The prognosis for skin necrosis caused by
levamisole-contaminated cocaine generally is good without long-term sequelae.5 Autoantibody
serologies normalize within weeks to months after stopping levamisole.5,8 Our patient recovered with conservative measures.
