DISCUSSION: SCLS affects both genders and all ages. Patients experience recurrent acute hypotension, anasarca, hypoalbuminemia, polycythemia, and paraproteinemia, predominantly IgG kappa light chains. Exact cause is currently unknown. Paraproteins may play an immunoregulatory role; 82% of SCLS patients present with a monoclonal gammopathy. SCLS stages include: 1) prodromal phase with upper respiratory flu-like symptoms, 2) acute leak phase with increased capillary permeability and fluid and protein extravasation causing edema and hypotension, and 3) the post leak phase with recruitment of fluid back into the vascular space. In one case series, 75% of deaths were related to hypoperfusion during the acute leak phase and fluid overload during the post leak phase. Complications include compartment syndrome, renal failure, and thrombosis. Treatment data is limited by disease rarity, but hemodynamic stability is achieved with IV fluids, pressors, albumin, and IVIG during the acute leak phase. Epoprostenol, immune modulation therapy, rituximab, infliximab, plasmapheresis, and steroids have been tried, but data is limited. Maintenance theophylline, terbutaline, and IVIG may decrease future exacerbations.