Liposarcoma presenting as an intraluminal ureteral mass

An 86-year-old woman with a previous excision of a large retroperitoneal low-grade liposarcoma presented with a 4-month history of persistent left flank discomfort. Workup revealed left hydronephrosis secondary to obstruction, which was caused by a recurrent liposarcoma in the intraluminal ureter. She underwent a left nephroureterectomy for symptomatic palliation. Pathologic study revealed high-grade liposarcoma. Despite negative surgical margins, the tumor rapidly recurred, leading to death only 4 months after surgery. This case highlights the aggressive nature of liposarcoma.