Spontaneous Tumor Lysis Syndrome in a Patient With a Known History of Chronic Lymphocytic Leukemia Prior to Cytotoxic Chemotherapy.

Tumor lysis syndrome (TLS) is an oncological emergency resulting in an imbalance of electrolytes released upon tumor cell death leading to life-threatening acute renal failure. Typically, TLS is triggered by cytotoxic chemotherapy; however, it can rarely occur spontaneously. Our case report presents a patient with a known malignancy, but not on any cytotoxic chemotherapy, who presents to the emergency department with metabolic derangements suggestive of spontaneous TLS. Our case highlights the importance of considering an uncommon manifestation of TLS despite the absence of cytotoxic chemotherapy. This case is unique as it demonstrates the manifestations of TLS in a patient with a known stable malignancy and discusses the subsequent management.