Systemic Capillary Leak Syndrome Presenting as Apparent Polycythemia Vera: A Critical Diagnostic Dilemma

Abstract

Polycythemia vera presents with true erythrocytosis (elevated red cell mass) and an expanded plasma volume, while apparent erythrocytosis presents with plasma volume contraction and a normal red cell mass. Here we report a case with recurrent episodes of severe apparent erythrocytosis, closely mimicking polycythemia vera, due to a rare condition known as systemic capillary leak syndrome (SCLS). This syndrome typically presents with the triad of hypotension, hemocencentration and hypoalbuminemia, combined with a monoclonal serum M-protein. Empirical treatment with intravenous immune globulin (IVIG) has successfully led to resolution of symptoms and correction of hemoconcentration in several reported cases as well as in our patient's case. It is important for clinicians to differentiate true erythrocytosis from apparent erythrocytosis, and to be aware of this rare syndrome causing the latter, as aggressive phlebotomy and overtreatment with crystalloid fluids could result in serious adverse events and should be avoided.