Spontaneous Tumor Lysis with Normal Electrolytes

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Introduction: Tumor lysis syndrome (TLS) leading to renal failure can occasionally occur prior to treatment in highly proliferative hematological malignancies. We present a case of AKI due to spontaneous TLS without the typical antecedent electrolyte derangements normally expected with TLS. Case Description: A 76-year-old male with no prior medical history presented to the emergency room with abdominal pain and weight loss. CT scan revealed a gastric mass, ascites and abnormal liver consistent with cirrhosis. Gastric biopsy revealed diffuse large B cell lymphoma. He initially had a bland UA and a slight increase in baseline creatinine. The primary team treated him for hepatorenal syndrome with no response. His renal function rapidly deteriorated and he became anuric. A follow up UA showed protein and blood. Although the uric acid (UA) was 13.7 mg/dL, the phosphorous and potassium remained in their normal ranges leading us away from a diagnosis of TLS and toward the possibility of a rapid progressive glomerulonephritis. On biopsy the renal tubules contained calcium oxalate and calcium phosphate crystals with vacuolization of the tubular epithelial cells and tubular changes consistent with prior uric acid crystal deposition. The glomeruli were normal. At this point the uric acid level had risen to 25 mg/dl. Rasburicase was initiated and the patient eventually recovered renal function. Discussion: In TLS, tumor cells lyse and release their intercellular electrolytes and purines (which are metabolized to uric acid) leading to elevated potassium, phosphorus and uric acid. Rarely the potassium and phosphorus can be normal. Our patient had renal failure further limiting the excretion of potassium and phosphate, making the normal levels of these electrolytes especially notable. Identifying the mechanism of normokalemia and normophosphatemia in spontaneous TLS may give us insight on how to diagnose it earlier, thus leading to earlier treatment.H&E with calcium oxalate crystals (arrow), tubular lumen that likely contained uric acid crystals (asterisks)

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