Ureteral Involvement in Non-Hodgkin Lymphoma: A Rare Case Report With Diagnostic Challenges

Ureteral involvement by diffuse large B-cell lymphoma (DLBCL) is an extremely rare clinical entity that can mimic primary urothelial carcinoma and pose a significant diagnostic challenge. A 70-year-old female patient initially presented to a urologist with renal colic. The patient denied fever, night sweats, unintentional weight loss, or prior hematologic disorders, and no peripheral lymphadenopathy was detected on physical examination. Multislice computed tomography (MSCT) revealed a ureteral mass, followed by cystoscopy with ureteral stent placement. Due to the strong clinical and radiological suspicion of upper tract malignancy, most likely ureteric urothelial carcinoma, radical nephroureterectomy was performed as the standard definitive management in the absence of a feasible preoperative tissue diagnosis. Definitive diagnosis was established through pathohistological and immunohistochemical analysis, confirming diffuse large B-cell non-Hodgkin lymphoma (NHL), germinal center B-cell-like subtype, with a high Ki-67 proliferative index (~80%). Staging work-up demonstrated localized disease (clinical stage I with extranodal involvement) by the Ann Arbor classification, with no evidence of systemic dissemination. The patient was treated with standard Rituximab, Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone (R-CHOP) immunochemotherapy, which was well tolerated. Early detection and timely initiation of therapy were associated with a favorable initial clinical course, as evidenced by clinical stabilization, absence of disease progression during follow-up, no early complications, and a good response to the R-CHOP regimen. This case highlights the extreme rarity of ureteral involvement by lymphoma, emphasizing the importance of considering lymphoma in the differential diagnosis of ureteral masses. It also underscores the critical role of histopathological evaluation in establishing an accurate diagnosis. Early recognition and appropriate treatment are essential for improving patient outcomes in such rare presentations.