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Abstract

Introduction: Tumor lysis syndrome (TLS) is an oncologic emergency that refers to the constellation of deranged metabolic state, characterized by hyperkalemia, hyperphosphatemia, hyperuricemia, hypocalcemia, and/or azotemia, secondary to rapid breakdown of tumor cells. It is a life threatening emergency that typically follows administration of chemotherapy or rarely may be spontaneous. Tumor lysis syndrome is most commonly seen in the setting of a malignancy of high proliferative rate, large tumor burden and/or in a malignancy with high sensitivity to treatment. TLS is more prevalent in hematologic malignancies and is rarely noticed in solid tumors, with only total of 10 cases reported from year 1977-2011 in association with breast cancer. All the patients who develop this complication are critically ill and at a high risk of grave consequences including death as a result of this syndrome. Case: A 28-year-old woman at 28 weeks of pregnancy with a history of breast cancer was brought to the ER in status epilepticus. She was intubated for airway protection and admitted to Medical Intensive Care Unit for close monitoring. Patient had been diagnosed with biopsy proven invasive ductal carcinoma of her breast with ER/PR positivity and Her-2-neu negativity, two years ago. She was started on Tamoxifen which she took for a year before discontinuing it a year ago. She declined any treatment that she was offered and did not have any further follow up with her oncologist since a year prior to her presentation. On her current admission, patient was noticed to have extensive metastatic disease involving cranium, ribs, cervical, thoracic and lumbar spine with multiple intracranial and hepatic lesions as well. During her hospital course, while she was in the ICU and before she received any type of chemotherapy her blood work demonstrated worsening hyperuricemia, hyperphosphatemia and hypocalcemia. Patient's laboratory work up revealed a uric acid level of 12.1mg/dL, with phosphate of 4.1mg/dL and calcium ranging from 6.9 - 8.1mg/dL. In light of her laboratory results, patient met "Cairo-Bishop" definition of tumor lysis syndrome. She was closely monitored in the Medical-Intensive care unit and was started on allopurinol and aggressive fluid therapy. Patient responded well to this intervention and over the course, she had a rapid decline in her uric acid levels and normalization of other electrolyte derangement. Fortunately, she did not develop any cardiac arrhythmia or recurrent seizure episodes. Discussion: Tumor lysis syndrome is one of the most dreaded complications of aggressive malignancies but is extremely rare in untreated non-hematologic solid tumors. In literature, 370 cases have been reported of TLS in solid tumors of which only 10 cases in association with breast cancer. In the year 2004, Cairo-Bishop definition was proposed with specific laboratory criteria for the diagnosis of Tumor lysis syndrome and was defined as any two or more abnormal serum values of uric acid, potassium, phosphate or calcium in presence of adequate hydration and use of hypouricemic agents. Presentation of this individual is of value because TLS is a rare occurrence in solid tumors but clinicians should be aware of it so to be able to diagnose and aggressively treat it, as it is associated with a poor clinical course and is very commonly complicated by cardiac arrhythmias, renal failure, recurrent seizures or sudden death. Thus, it is recommended that all the patients who develop or are suspected to have tumor lysis syndrome deserve close monitoring and follow up in the intensive care unit.