Tumor Lysis Syndrome

Tumor lysis syndrome refers to a metabolic derangement due to high tumor burden and rapid cell turnover, resulting in release of intracellular contents. Patients may present with acute renal failure and metabolic derangements, including:

• Hyperuricemia from purine metabolism
• Hyperkalemia
• Hyperphosphatemia
• Hypocalcemia caused by hyperphosphatemia and the resultant precipitation of calcium phosphate.

While tumor lysis syndrome is most commonly a complication of treatment of blood-borne malignancies such as acute lymphocytic leukemia and poorly differentiated lymphomas (e.g., Burkitt), cases of tumor lysis syndrome related to treatment of solid organ tumors have also been reported. Treatment modalities that can lead to tumor lysis syndrome include chemotherapy, radiation therapy, immunotherapy, interferon therapy, hormonal therapy, surgery, chemoembolization, and radiofrequency ablation. Cases of spontaneous tumor lysis syndrome have also been reported.

The Cairo-Bishop definition includes two classes of tumor lysis syndrome:
Laboratory tumor lysis syndrome: Any 2 of the following:

• Uric acid > 8 mg/dL or 25% increase
• Potassium > 6 mEq/L or 25% increase
• Phosphate > 4.5 mg/dL or 25% increase
• Calcium < 7 mg/dL or 25% decrease

Clinical tumor lysis syndrome: Laboratory tumor lysis syndrome plus one or more of the following:

• Creatinine > 1.5x upper limit of normal
• Seizure
• Cardiac arrhythmia
• Sudden death

Management focuses on prevention in high-risk patients with allopurinol and hydration. Treatment after renal failure has occurred involves hydration and loop diuretics to maintain urine flow, recombinant uricase (catalyzes insoluble uric acid), and hemodialysis.

Imaging findings can include nephromegaly, renal stone formation with obstructive uropathy, and findings of posterior reversible encephalopathy syndrome (PRES).

References

• Cairo MS, Bishop M. Tumour lysis syndrome: new therapeutic strategies and classification. Br J Haematol. 2004 Oct;127(1):3-11.
• Kaito E, Terae S, Kobayashi R, Kudo K, Tha KK, Miyasaka K. The role of tumor lysis in reversible posterior leukoencephalopathy syndrome. Pediatr Radiol. 2005 Jul;35(7):722-7.
• Lehner SG, Gould JE, Saad WE, Brown DB. Tumor lysis syndrome after radiofrequency ablation of hepatocellular carcinoma. AJR Am J Roentgenol. 2005 Nov;185(5):1307-9.
• Parisi MT, Fahmy JL, Kaminsky CK, Malogolowkin MH. Complications of cancer therapy in children: a radiologist's guide. Radiographics. 1999 Mar-Apr;19(2):283-97.