Xanthogranulomatous pyelonephritis and agglutination of erythrocytes

Previously unreported association of xanthogranulomatous pyelonephritis and agglutination of red blood cells is described in a twenty-two-year-old patient with urinary tract infection, flank pain, and a palpable abdominal mass. Blood compatability testing problems occurred secondary to the presence of a nonspecific cold agglutinin in her serum, but presented no clinical problems when warm blood was administered. This cold agglutinin cleared after nephrectomy, thus adding this association to the other manifestations of renal tumefactive processes.