BACKGROUND: Secondary polycythemia is a potential complication of an erythropoietin-secreting renal cell carcinoma. Increased red blood cell mass can elevate blood viscosity, which can impair blood flow, making individuals susceptible to vaso-occlusive events. One of the serious potential complications of a hyper-viscous state is ischemic stroke.

CASE REPORT: We present the case of a patient who was brought to the Emergency Department with right-sided extremity weakness and slurred speech consistent with acute ischemic stroke. MRI showed acute infarct involving the left corona radiata and posterior limb of the left internal capsule. On admission, he was found to have increased hemoglobin and hematocrit. An ultrasound of his abdomen found a heterogeneous mass of the right kidney, which was confirmed with CT scan. The patient remained in the hospital for 6 days. His hospital course was complicated by the incidental findings of polycythemia and a renal mass consistent with renal cell carcinoma. His hemoglobin and hematocrit remained elevated throughout his hospital course, and his erythropoietin level was found to be elevated as well.

CONCLUSIONS: High blood viscosity is associated with increased incidence of cardiovascular complications, including reduced cerebral blood flow. This case report suggests that polycythemia secondary to an erythropoietin-secreting renal cell carcinoma can lead to ischemic stroke. After surgery to remove the carcinoma, the secondary polycythemia may resolve.

Keywords: Carcinoma, Renal Cell, Erythropoietin, Polycythemia, Stroke