Résumé
Essential thrombocythemia (ET) is a clonal stem cell disease characterized by isolated thrombocytosis and thrombohemorrhagic complications. We describe an unusual case of ET primarly presenting with skin symptoms including erythromelalgia and livedo reticularis (racemosa-type). Persistent thrombocytosis, bone marrow findings, JAK2 gene mutation, and markedly decreased ristocetin-cofactor activity were consistent with the diagnosis of ET and acquired von Willebrand disease. Elevated antiphospholipid antibodies were also found. The present case highlights the complex nature and diagnostic challenge of myeloproliferative disorders such as ET, which can involve multiple organ systems and often shows a variety of microvascular complications, coagulation anomalies, and autoimmune phenomena.