Spontaneous Tumor Lysis Syndrome Secondary to Metastatic Small Cell Lung Cancer.

Tumor lysis syndrome (TLS) is an oncology emergency caused by the lysis of tumor cells that releases cell contents into the blood. TLS is typically associated with leukemia following the initiation of chemotherapy. Spontaneous TLS has been seen in hematologic malignancies, but the incidence of spontaneous TLS in solid tumors is rare, and only nine cases have been reported in small cell lung carcinoma. We present a case of a patient who presented with severe metabolic acidosis and electrolyte abnormalities consistent with TLS. At presentation, our patient was found to have small cell lung carcinoma with metastasis to the liver. This patient was managed with bicarbonate, rasburicase, allopurinol, and calcium replacement and started on continuous renal replacement therapy, but unfortunately was transitioned to comfort care and passed away. Risk factors for spontaneous TLS include bulky disease, elevated lactate dehydrogenase, elevated white blood cell counts, renal compromise, and abdominal organ involvement. The most common laboratory findings for TLS include metabolic acidosis and hyperuricemia, hyperphosphatemia, hyperkalemia, and hypocalcemia. Cases of spontaneous TLS, however, have been noted to have smaller elevations in phosphate levels. Spontaneous TLS is a rare but potentially fatal complication that can be seen in small cell lung carcinoma.