Most mediastinal masses are initially suspected based upon chest X-ray findings, with additional imaging (especially contrast-enhanced CT) being the primary modality to provide additional information about the nature and extent of the pathologic process.

Patient management requires a definitive diagnosis, which generally requires an adequate tissue sample. This may be obtained either by biopsy or as part of a planned therapeutic intervention [1, 2].

Tumor lysis syndrome (TLS) is an oncologic emergency that is caused by massive tumor cell lysis and the release of large amounts of potassium, phosphate, and uric acid into the systemic circulation. Deposition of uric acid and/or calcium phosphate crystals in the renal tubules can result in acute kidney injury, which results in oliguria or anuria. TLS is observed most frequently in patients with aggressive and highly aggressive lymphomas (particularly the Burkitt subtype) and T-cell acute lymphoblastic leukemia (ALL) following the initiation of cytotoxic therapy, although it may also occur spontaneously and/or in other tumor types with a high proliferative rate, large tumor burden, or high sensitivity to cytotoxic therapy [3–6].