Tumor Lysis Syndrome in a Solid Tumor: A Case Report of a Patient with Invasive Thymoma
A 40-year-old female presented to the emergency room with a three-day history of progressive dyspnea due to pleural effusion in February 2010. A computed tomography (CT) scan of the chest showed an extensive soft-tissue mass, measuring 12×8 cm in size, in the anterior mediastinum extending into the right hemithorax and pericardial space (). Percutaneous gun biopsy of the right anterior mediastinal mass confirmed WHO type B3 thymoma (), classified according to the Masaoka clinical staging system. Due to the unresectable state of disease, neoadjuvant chemotherapy was scheduled in order to reduce the tumor size prior to surgery. From February 19 to April 5, 2010, the patient received three cycles of systemic chemotherapy with a regimen consisting of docetaxel (75 mg/m2 i.v. over 1 hour on day 1) and cisplatin (75 mg/m2 i.v. over 1 hour on day 1). Despite a slight interval decrease in the size of thymoma and a decreased amount of pericardial and pleural effusion after three cycles of chemotherapy, two more cycles of chemotherapy were administered due to incomplete resectability and patient's reluctance.\nDue to disease progression during follow-up, the patient received four additional cycles of systemic chemotherapy with a regimen consisting of cyclophosphamide (500 mg/m2 i.v. over 1 hour on day 1), doxorubicin (50 mg/m2 i.v. over 30 minutes on day 1), and cisplatin (50 mg/m2 i.v. over 1 hour on day 1) from May 11 to July 26, 2010. The disease status remained stable for 11 months after second-line chemotherapy, and thereafter showed slow progress. On April 12, 2012, the patient complained of aggravation of dyspnea and chest X-ray showed massive pleural effusion on the right side of the chest. Chest CT showed aggravation of anterior mediastinal thymoma with extension into the middle mediastinum and surrounding pericardium as well as the entire right side of pleura (). A percutaneous pig-tail catheter was inserted into the right pleural space for drainage of malignant pleural effusion. Third-line chemotherapy was started on April 18, 2012, with a regimen consisting of paclitaxel (175 mg/m2 i.v. over 3 hours on day 1), ifosfamide (2,500 mg/m2 i.v. over 2 hours on days 1 and 2), and mesna (500 mg/m2 i.v. over 15 minutes on days 1 and 2). After completion of one cycle of chemotherapy, tachypnea, tachycardia, and oligouria were detected on the second day of chemotherapy. Blood chemistry showed the following: potassium, 5.3 mmol/L (3.5-5.1 mmol/L); phosphorus, 20.0 mg/dL (2.5-4.5 mg/dL); uric acid, 25.0 mg/dL (2.4-6.0 mg/dL); calcium, 5.5 mg/dL (8.4-10.2 mg/dL); arterial blood gas analysis, pH 7.24 (7.35-7.45); bicarbonate, 9.8 mmol/L (21.0-31.0 mmol/L); urea nitrogen, 73.6 mg/dL (8.0-22.0 mg/dL); creatinine, 3.74 mg/dL (0.6-1.1 mg/dL); lactate dehydrogenase (LDH), 4,153 IU/L (240-480 IU/L); and urine pH, 5.5 (5.0-8.0). Based on the patient's clinical symptoms and consequent laboratory findings, it was determined that the patient had developed classical signs of TLS, including acute kidney injury. The patient was immediately transferred to the intensive care unit for treatment, including aggressive hydration, intravenous bicarbonate for urine alkalinization, allopurinol, and repeated hemodialysis. On day 3, continuous renal replacement therapy was started and continued until day 5. During the following days, the patient's clinical symptoms and signs, such as dyspnea, tachypnea, and tachycardia, showed improvement, and the biochemical markers, including metabolic acidosis, hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia, returned to normal (). The plasma level of LDH was 1,139 IU/L before chemotherapy, increasing to 4,153 IU/L on day 3, and decreased to 498 IU/L on day 22 ().\nHemodialysis was performed twice per week from April 25 to May 9, due to persistent azotemia despite adequate urine output (). Serum urea nitrogen and creatinine concentration decreased to 15.2 mg/dL and 1.45 mg/dL, respectively, on day 35; therefore, further hemodialysis was not required. Of particular interest, remarkable regression of the preexisting tumor after one cycle of third-line chemotherapy was observed on a follow-up chest CT scan (). The patient has remained on the same regimen with partial response to chemotherapy without recurrence of TLS.