Systemic Capillary Leak Syndrome Mimicking Polycythemia Vera.
Authors: Kamal Arif H. , Greipp Philip R. 
Published: April 2020

Abstract
Systemic capillary leak syndrome (SCLS) is a vascular disorder characterized by intermittent episodes of hypotension and edema from increased vascular permeability. Patients present with resultant dramatic shifts in plasma volume from intravascular to extravascular spaces. Diagnosis requires observation of severe hemoconcentration and hypoalbuminemia during acute attacks. Typically, laboratory evaluation of hematocrit and albumin is normal when patients are not symptomatic. Concomitantly, and of unknown significance, a monoclonal protein is also frequently discovered. We present the case of a patient whose increased hematocrit suggested polycythemia vera, but whose total clinical picture of hypotension, hemoconcentration and hypoalbuminemia confirmed the diagnosis of SCLS.
A 54-year old gentleman was referred for evaluation of polycythemia vera that was diagnosed after a series of dramatic hospitalizations for near-syncope. The patient had no chronic illnesses, negative family history for hematologic abnormalities, and was otherwise in his usual state of good health when a complaint of sudden lightheadedness and pre-syncope led to an emergency room evaluation. There he was found to be severely hypotensive and was resuscitated with intravenous fluids. Initial laboratory evaluation showed a hematocrit of 60%. Further workup revealed an increased red cell mass. For the presumptive diagnosis of polycythemia vera, the patient was phlebotomized once and, interestingly, did not require any further phlebotomy for almost three years. During this interim, he remained relatively asymptomatic with only occasional bouts of lightheadedness that would abort with increased fluid hydration. Phlebotomy was again used when the patient presented with near-syncope, hypotension, and vomiting accompanied by significant extremity swelling. The hematocrit was found to be greater than 80%. The patient recovered with aggressive fluid resuscitation and was discharged on a low-dose aspirin with the continued empiric diagnosis of polycythemia vera. During that year, the patient recovered from four other similar episodes that resolved after fluid resuscitation and where phlebotomy was used. The most severe episode involved a protracted ICU stay for severe hypotension complicated by severe extremity edema and resultant compartment syndrome and ischemic muscle necrosis. With the concern of adrenocortical dysfunction leading to these hypotensive episodes, the patient was started on low dose daily steroids. While on this, the patient reported less frequency and severity of his almost-daily symptoms of lightheadedness and edema. In fact, attempts at tapering the steroid dose down resulted in a return of the minor symptoms and with continued steroids, no further hospitalizations were needed. During our evaluation, we confirmed a normal hematocrit and albumin while asymptomatic and the presence of a monoclonal protein.
This case represents a common clinical history of patients who are ultimately diagnosed with SCLS. Often, the significance of the observed hypotension in concert with laboratory evidence of hemocentration and hypoalbuminemia is not initially appreciated. Although current attack prophylaxis regimens for SCLS use terbutaline and theophylline, steroids had historically shown occasional benefit in some patients. SCLS still carries a significant mortality risk and prompt recognition of this syndrome and initiation of an appropriate prophylaxis regimen is crucial.