Abstract
This case report presents a 72-year-old male with a history of diffuse large B-cell lymphoma (DLBCL) who was found to have a 2.6 cm left renal mass during surveillance imaging. The clinical challenge lay in distinguishing between a recurrence of DLBCL and a new primary renal cell carcinoma (RCC), as both diseases are treated with different paradigms. A biopsy confirmed clear cell RCC, and the patient underwent a left nephrectomy with no evidence of metastasis or recurrence of lymphoma. This case highlights the importance of a biopsy in clarifying the diagnosis of renal masses, particularly in patients with prior malignancies. It also explores the potential role of radiation therapy as an alternative treatment option in cases where surgery may pose significant risks. A more comprehensive multidisciplinary approach would optimize patient outcomes and ensure individualized care.