BACKGROUND Plasmacytoid is a rare histological variant of urothelial carcinoma (UC). Since the first reported case of plasmacytoid urothelial carcinoma (PUC), in 1991, only about 100 cases have since been reported, with most cases involving the bladder. Urothelial carcinomas of the upper urinary tract represent only 5% of urothelial cancers. To the best of our knowledge, there has only been 1 reported case of PUC of the ureter. PUC is a highly aggressive disease, with a poor prognosis. We present a rare biopsy-proven case of PUC of the ureter with retroperitoneal metastasis. CASE REPORT A 60-year-old man came into the hospital with complaints of a 5-day history of generalized abdominal pain, nausea, and vomiting, with no associated urinary symptoms prior to admission. CT demonstrated small bowel obstruction (SBO) and obstructive uropathy due to a right ureteric mass. Exploratory laparotomy, small bowel resection, gastrostomy tube placement, and umbilical hernia repair were all done. Histology and immunohistochemistry were compatible with plasmacytoid variant of urothelial cancer. He underwent a cystouretoscopy and a right ureteral stent placement with a right ureteroscopy. Final CT abdomen/pelvis revealed recurrent SBO before the ileocecal valve, possibly due to carcinomatosis. Ileocecal resection with end ileostomy placement was done. Systemic treatment will begin as an outpatient. CONCLUSIONS PUC arising from the ureter is rare, and retroperitoneal metastatic disease has not been reported previously. Here, we compare the clinical manifestations of the more common PUC of the bladder with our case. From this we are able to learn more about the disease and its presentation.