[Systemic capillary leak syndrome presenting remarkable erythrocytosis].

Systemic capillary leak syndrome (SCLS) is a disorder characterized by hypotension, edema, and an increased hematocrit (Ht) due to sudden leakage of plasma into the extravascular space through some unknown mechanism, in which monoclonal gammopathy is observed. A 30-year-old man visited our emergency department because of abdominal pain, and was admitted to our hematology department because of a markedly increased hemoglobin concentration reaching 26.2 g/dl. The polycythemia was thought to be pseudo-polycythemia due to hemoconcentration, and we diagnosed the patient as having SCLS based on the triad of increased hematocrit, whole-body edema which was especially marked in the lower extremities, and monoclonal gammopathy. The patient recovered after administration of extracellular fluids and albumin, but the attacks recurred. Prophylaxis with terbutaline sulfate, theophylline and corticosteroid reduced the frequency of severe attacks. Because there is possibility that patients with SCLS may be admitted to hematology departments due to severe erythrocytosis, we report this case to increase the awareness of hematologists that SCLS is one of the important differential diagnoses of erythrocytosis.