Cureus. 2020 Oct 17;12(10):e11002. doi: 10.7759/cureus.11002.
Tumor lysis syndrome (TLS) is a constellation of metabolic derangements that occur as a consequence of rapid cell turnover in malignancy and the release of intracellular solutes - potassium, phosphate, and nucleic acid metabolites. TLS classically occurs following chemotherapy, with severe renal failure. However, the entity referred to as spontaneous TLS occurs without a precipitating factor of chemotherapy, radiotherapy, steroid therapy, or immunotherapy and can develop in both hematologic and solid malignancies. Here, we report a rare case of a patient who presented with nonspecific symptoms, hyperphosphatemia, hyperuricemia, but hypercalcemia, resultant acute renal failure, with a large mediastinal mass and a pericardial effusion, who was later found to have spontaneous TLS. The workup led to the diagnosis of T-cell leukemia. Spontaneous TLS is often the first manifestation of occult or undetected malignancy, making this oncologic emergency a challenge to manage. The early diagnosis and prompt treatment of spontaneous TLS can reduce morbidity and mortality for patients with an otherwise curable disease.