Young Seok Lee, et al : Treatment of the acute phase of SCLS with Pentastarch 131 creatinine (BUN/Cr): 32.8/1.9 mg/dL, total protein/albumin: 3.7/1.7 g/dL, C-reactive protein (CRP): 3.1 mg/L and the monoclonal IgG-kappa was positive. The laboratory test performed later showed C3/C4: 34.0/6.9 mg/dL and IgA/G/M: 101/810/102 IU/mL, respectively. The C1 esterase inhibitor level was normal and bone marrow biopsy showed no evidence of multiple myeloma. Despite intravenous injection of a combination of 9 L of normal saline solution and inotropic drugs, her systolic blood pressure did not increase and she developed respiratory failure resulting from pulmonary edema. The central venous pressure (CVP) was 3 cmH2O. We stopped using normal saline solution and started using 10% pentastarch (Pentaspan inj, Jeilpharm, Korea). After we started infusing 10% pentastarch 500 mL every 8 hours, her blood pressure began to increase. We also used intravenous methylprednisolone, aminophylline and calcium. Her blood pressure and the CVP recovered to the normal levels the next day. The hemoglobin level measured at that time was 16.8 g/dL, with a hematocrit of 47%, leukocytes: 26,200/mm2, platelets: 93,000/mm2, BUN/Cr: 35.4/1.2 mg/dL and prothrombin time (PT): 2.8 INR. We thought that PT prolongation was a side effect of pentastarch, based on some previous reports. Therefore, we stopped using it. The pulmonary edema and bilateral pleural effusion due to the massive injection of normal saline solution were treated with diuretics. There was no long-term complication and no more attacks during 1 year follow-up. Case 2 A 36 year-old female came to the hospital complaining of dyspnea and generalized edema that had started that very day. She developed upper respiratory infection 3 days before admission, but she didn't get any medication. She had a past history of 5 admissions at another hospital for the same symptoms; she underwent various examinations at that time but didn't get the proper diagnosis. She finally turned out to have SCLS at our hospital 2 years before this admission and was being followed up. She was alert and the systolic blood pressure was 40 mmHg, heart rate: 130 beats/min, respiratory rate: 30 breaths/min and a temperature of 36℃. Her breath sounds were normal. According to the laboratory finding taken on admission, her hemoglobin level was 21.1 g/dL, hematocrit: 62.7%, leukocytes: 49,700/mm2, platelets: 297,000/mm2, BUN/Cr: 22.6/2.7 mg/dL, total protein/albumin: 4.4/2.5 g/dL, CRP: 4.9 mg/L and CVP: 2 cmH2O. The serum protein electrophoresis detected monoclonal gammopathy and the immunofixation test detected IgG kappa. The C1 esterase inhibitor level was normal and the bone marrow biopsy had no evidence of multiple myeloma. We started injecting 2 L of 10% pentastarch, along with inotropic drugs, instead of normal saline solution. One hour after pentastarch injection, her blood pressure began to rise and the CVP was 11 cmH2O, but no improvements were seen in the laboratory data that was checked at that time. Later, we injected methylprednisolone, calcium, aminophylline and after that, her blood pressure didn't drop and the patient's condition gradually got better. Because she did not undergo massive fluid therapy, she did not suffer from respiratory failure resulting from pulmonary edema. During her 5 day hospital stay, the patient showed improved an hemoglobin level: 10.5 g/dL, hematocrit: 31.0%, BUN/Cr: 11.4/0.4 mg/dL and protein/albumin: 5.2/3.4 g/dL. The patient was discharged after being administered oral prednisolone and theophylline. DISCUSSION Systemic capillary leak syndrome is a rare condition that was discovered by Clarkson et al in 19601). The prodromal symptoms are fatigue, nausea, abdominal pain and syncope. It can also present with decreased blood pressure, rhabdo- myolysis, generalized edema and acute tubular necrosis- induced renal failure2, 3). This syndrome has two phases. The initial capillary leak phase may last 1 to 4 days and this is the essential phase of acute hypovolemia that's due to marked extravasation of intravascular fluids and macromolecules. Therefore, hemoconcentration, leukocytosis, an increased IgM concentration and a decreased concentration of albumin, IgG, C3 and C4 may occur, as well as extravasation of up to 70% of the plasma3). In the recruitment phase, the initially extravasated fluids and macromolecules shift into blood vessels, causing a severe acute intravascular fluid overload. The disappearance of renal shut-down and an increased urine output are the main characteristics of this stage. But fluid overload can also cause pulmonary edema, as in the case of the first patient, who suffered from pulmonary edema in the recruitment phase and she was treated by diuretics3). The pathogenesis of this syndrome is not yet clear. Though some of these patients have been diagnosed with multiple myeloma during follow-up, this syndrome is supposed to have something to do with monoclonal gammopathy without any evidence of multiple myeloma3). According to Amoura et al. among 29 SCLS patients who had monoclonal antibody, 16 people of them had IgG kappa, 6 of them had IgG lambda, 1 of them had IgA lambda, and one had mixed a form of IgG kappa and IgG lambda4). As seen from above, most of these patients had IgG kappa, like our own patients. Assaly et al attributed the mechanism of endothelial cell leak first to widening of the intercellular gaps resulting from increased intracellular calcium, and secondarily to endothelial cell damage and destruction. They also described apoptosis that was caused by various inflammatory responses as a mechanism of this