Haematuria As the Initial Manifestation of Bladder Plasmablastic Lymphoma: A Report of a Rare Case and Literature Review.

Plasmablastic lymphoma (PBL) is an aggressive and uncommon variant of diffuse large B-cell lymphoma, most frequently associated with immunocompromised states. Although extranodal disease is characteristic, involvement of the urinary bladder is exceptionally rare and may mimic primary urothelial malignancy both clinically and histologically. We report the case of a 62-year-old man with a previous history of high-grade diffuse large B-cell lymphoma in remission who presented with acute gross haematuria. Imaging demonstrated bladder wall thickening with associated hydronephrosis. Transurethral resection of the bladder lesion, followed by detailed histopathological and immunohistochemical analysis, confirmed plasmablastic large B-cell lymphoma involving the bladder. This case underscores the importance of maintaining a broad differential diagnosis in patients presenting with haematuria, particularly those with a prior history of haematologic malignancy. A review of the literature highlights the rarity of bladder involvement and the diagnostic challenges associated with this entity.