Abstract
Upper urinary tract adenocarcinoma is a rare malignancy with a challenging diagnosis and limited treatment options. This paper presents a rare case of primary ureteral adenocarcinoma, an exceptionally uncommon malignancy typically associated with genitourinary or extra-genitourinary tumors. The 53-year-old patient, with a history of gastric adenocarcinoma and prior chemotherapy, developed left flank pain. Imaging revealed a tumor in the distal ureter, leading to a left radical nephroureterectomy. Histopathology confirmed an intestinal-type adenocarcinoma of the upper urinary tract. Unique to this case, the adenocarcinoma originated separately from the stomach. Despite planning adjuvant chemotherapy, the patient's deteriorating condition led to palliative care, and he passed away three months post-diagnosis. The paper underscores the challenges in diagnosing and treating such rare malignancies, emphasizing the need for further research to understand their etiology and optimal management.