Background <p>Primary angiosarcoma of the urinary system is a rare, aggressive endothelial malignancy, with only 113 cases of renal angiosarcoma documented as of 2023. Angiosarcoma of the ureter is a much less common condition. Clinical manifestations commonly include flank pain, hematuria, an abdominal mass, weight loss, fatigue, and dizziness. In rare instances, spontaneous tumour rupture may result in retroperitoneal haemorrhage. Management primarily involves surgical resection, often complemented by adjuvant radiation therapy and chemotherapy.</p> Case summary <p>An 88-year-old patient was admitted to the hospital due to weight loss, urine retention and macroscopic hematuria. Initial evaluation with US and CT urography found a tumorous lesion in the pelvic part of the right ureter. PET/CT confirms a hypermetabolic enhancing lesion of the right ureter, with no metastatic lymph nodes or evidence of distant metastases. The patient was indicated for a laparoscopic right-sided nephroureterectomy, and the surgery was completed without complications. Histopathological evaluation confirmed the diagnosis of angiosarcoma, which was classified as grade II according to the FNCLCC classification and staged as pT3N0M0. A month after the surgery, the patient was bleeding from the right internal iliac artery. Embolisation was performed, and stent grafts were inserted. A few days later, the patient died from sepsis.</p> Conclusion <p>Angiosarcoma within the urinary system is rare. To date, only three cases of angiosarcoma of the ureter have been reported. Cases of angiosarcoma originating in the urinary bladder, kidney or other retroperitoneal structures were reported more frequently. Surgical intervention is the principal therapeutic option, followed by adjuvant therapy. Establishing standardised diagnostic and treatment protocols is crucial to improving patient outcomes, but at this moment, case reports are the only source of information on clinical management.</p>