Objectives. Renal pelvic subepithelial hematoma is a rare but significant clinical mimic of neoplasm. Investigation and treatment of this diagnostic problem are uncertain.

Methods. We add 6 patients with this entity to the 15 previously published cases. All 6 were clinically suspected of having cancer, and 5 underwent nephrectomy.

Results. The most common clinical findings are gross hematuria (19 of 21 cases) and acute onset of flank pain (13 of 21 cases). Intravenous urogram usually reveals a filling defect at the ureteropelvic junction. Pathologic findings include massive subepithelial and peripelvic hemorrhage, hydronephrosis, cortical infarcts, and renomegaly. Two of our patients have previously undescribed clinical associations, including one who was 2 weeks postpartum and another with ureteropelvic junction obstruction. In addition, our patient with obstruction is the first with subepithelial hematoma to be treated successfully with pyeloplasty.

Conclusions. Subepithelial pelvic hematoma may be effectively treated with pyeloplasty or partial nephrectomy if distinguished from cancer preoperatively. Awareness of this rare entity may allow preoperative identification, but this has not been possible to date.