以腎積水表現之輸尿管侵犯型濾泡性Ｂ細胞淋巴瘤：罕見病例報告

黃國倫¹、吳俊賢^1、2、林嘉祥^1、2、吳振宇^1、2

¹義大醫療財團法人義大醫院 泌尿科；

²義守大學 醫學系

Follicular B-Cell Lymphoma Involving the Ureter Presenting with Hydronephrosis: A Rare Case Report
Guo-Lun Huang¹, Chun-Hsien Wu^1,2, Victor C. Lin^1,2, Richard C. Wu^1,2

¹ Department of Urology¹, E-Da Hospital, Kaohsiung, Taiwan;

² School of Medicine, College of Medicine², I-Shou University, Kaohsiung, Taiwan

Introduction: Lymphoma involving the genitourinary tract is uncommon, and ureteral involvement is particularly rare because the ureter lacks native lymphoid tissue. When lymphoma affects the ureter, patients may present with hydronephrosis or ureteral obstruction, often mimicking urothelial carcinoma or retroperitoneal fibrosis on imaging. Because radiologic findings are nonspecific, histopathological confirmation is essential for accurate diagnosis. We report a rare case of follicular B-cell lymphoma involving the ureter presenting with hydronephrosis, initially suspected to be ureteral malignancy.

Case report: A 69-year-old woman with a history of diabetes mellitus and hyperthyroidism presented to the emergency department with fever and left flank pain. Laboratory tests showed leukocytosis and elevated C-reactive protein, and urinalysis revealed pyuria and bacteriuria. Ultrasonography demonstrated moderate left hydronephrosis. Non-contrast abdominal computed tomography (CT) revealed circumferential periureteral soft-tissue infiltration involving the left upper ureter with hydronephrosis, raising suspicion for ureteral malignancy, lymphoma, or retroperitoneal fibrosis (Fig. 1A). Ureteroscopic biopsy initially revealed urothelial dysplasia. Given that imaging findings remained suspicious, a CT-guided biopsy of the periureteral lesion was subsequently performed. Histopathological examination demonstrated small- to medium-sized atypical lymphoid cells positive for cluster of differentiation 20 (CD20), B-cell lymphoma 2 (Bcl-2), cluster of differentiation 10 (CD10), B-cell lymphoma 6 (Bcl-6), and cluster of differentiation 23 (CD23), consistent with low-grade follicular B-cell lymphoma (Fig. 2). For staging evaluation, fluorine-18 fluorodeoxyglucose positron emission tomography–computed tomography (18F-FDG PET/CT) demonstrated increased uptake in the left upper ureter and the fourth lumbar vertebra (L4). Bone marrow examination showed no lymphoma involvement, and the final diagnosis was stage IV follicular lymphoma involving the ureter and vertebra. A double-J ureteral stent was placed to relieve obstruction. The patient subsequently received rituximab-based chemotherapy consisting of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP regimen). During treatment, the patient developed severe urinary tract infection requiring hospitalization and intravenous antibiotics, which temporarily interrupted chemotherapy. The patient is currently under ongoing oncologic treatment and follow-up.

Conclusion: Ureteral involvement by lymphoma is extremely rare and may present as hydronephrosis or ureteral obstruction, frequently mimicking ureteral malignancy. Because imaging findings are nonspecific, tissue biopsy is essential for establishing the correct diagnosis and avoiding unnecessary surgical intervention. Systemic chemotherapy remains the mainstay of treatment.