Abstract
Tumor lysis syndrome (TLS) is a life-threatening complication that can arise after initiation of cytotoxic chemotherapy in highly proliferative hematological malignancies, such as leukemias or lymphomas. Prophylactic measures, such as allopurinol, rasburicase, and hydration, are commonly initiated in these types of malignancies prior to chemotherapy to prevent TLS. However, in rare instances, TLS can still occur despite the initiation of prophylactic treatment. When TLS develops, the patient can experience various complications, such as kidney injury, muscle fatigue, paralysis, cardiac arrhythmias, and even death. Our case presents an 83-year-old male with newly diagnosed stage IV diffuse large B-cell lymphoma (DLBCL) who developed TLS following chemotherapy despite receiving the standard prophylactic treatment of IV fluids, rasburicase, and allopurinol. This case highlights the importance of identifying signs of TLS and initiating appropriate treatment even in patients receiving prophylaxis.