Primary Extranodal Non-Hodgkin Lymphoma of the Urinary Bladder: A Case Report

Background

Primary extranodal non-Hodgkin lymphoma (NHL) of the urinary bladder is an exceptionally rare malignancy, accounting for less than 0.2% of extranodal lymphomas. Its clinical and radiological features often mimic urothelial carcinoma, making diagnosis challenging. Case Presentation: A 50-year-old male presented with a six-week history of painless gross hematuria, dysuria, increased urinary frequency, and intermittent left flank pain. He had no constitutional symptoms suggestive of systemic lymphoma. Clinical Findings and Investigations: Ultrasonography and CT intravenous urography revealed an irregular bladder mass involving the left lateral wall and vesicoureteral junction, causing severe left hydroureteronephrosis. Cystoscopy demonstrated papillary and sessile bladder lesions. Following transurethral resection of the bladder tumor (TURBT), histopathology with immunohistochemistry confirmed diffuse large B-cell lymphoma (DLBCL) of the urinary bladder. Intervention and Outcome: The patient received six cycles of R-CHOP chemotherapy, achieving marked clinical and radiological regression. Follow-up PET-CT and repeat TURBT showed complete remission with no evidence of recurrent disease. Repeat biopsy revealed only mild chronic cystitis.