Polycythaemia treated with nephrectomy.

Unilateral renal cystic disease (URCD) is a rare, non-familial non-progressive renal disorder not associated with cysts in other organs in contrast to autosomal dominant polycystic kidney disease. Only 55 cases have been published in the world literature. Renal diseases are a well-recognized etiology of secondary erythrocytosis but not in URCD. We can present at case of URCD and secondary polycythaemia. Only one case with similar history has been reported, but in our case, the polycythaemia was confirmed by measuring the erythropoietin (EPO) level in the cyst fluid.