Incidental detection of high-grade T cell non-Hodgkin lymphoma mimicking urinary bladder carcinoma: a diagnostic challenge

Abstract

Non-Hodgkin lymphoma (NHL) is a heterogeneous group of lymphoid malignancies that can occasionally present with atypical clinical and radiological features, leading to significant diagnostic challenges. Incidental detection during evaluation for other suspected malignancies is uncommon. We report the case of a 65-year-old male who presented with radiological findings suggestive of a urinary bladder neoplasm with metastatic lymphadenopathy. The patient underwent cystoscopy with transurethral resection of bladder tumor (TURBT) and bilateral double-J (DJ) stenting. Histopathological examination of the bladder tissue revealed only chronic inflammatory changes consistent with cystitis, with no evidence of malignancy. Owing to persistent generalized lymphadenopathy, a biopsy of the right iliac lymph node was subsequently performed. Histopathological examination demonstrated features of a malignant lymphoid neoplasm, and immunohistochemistry confirmed a diagnosis of high-grade mature T-cell NHL, with tumor cells positive for CD3, CD4, CD5, and CD7 and a high proliferative index (Ki-67: 90-95%). PET-CT further supported the diagnosis by demonstrating widespread metabolically active lymphadenopathy consistent with a lymphoproliferative disorder. This case highlights an unusual presentation of high-grade T-cell NHL mimicking urinary bladder carcinoma with nodal metastasis and emphasizes the critical role of histopathological examination and immunohistochemistry in establishing the correct diagnosis when clinical and radiological findings are discordant. Early recognition of such atypical presentations is essential to avoid misdiagnosis, facilitate timely initiation of appropriate therapy, and improve patient outcomes.