“…There are less than 150 reported cases worldwide [1,3]. ISCLS is of unknown etiology, but thought to be the result of transient endothelial dysfunction due to endothelial contraction, apoptosis, and injury [1] contributed by vascular endothelial growth factor (VEGF), complement, leukotrienes, and cytokines [4]. As in the patient in our case report, ISCLS is often misdiagnosed as polycythemia, polycythemia vera, or sepsis.…”