Rare presentation of renal failure related to tumor lysis syndrome

Background: tumor lysis syndrome (tls) which mostly occurs in lymphoproliferative malignancies after the start of chemotherapy is an oncologic emergency. manifestations of metabolic imbalance including increasing hyperkalemia, hyperphosphatemia, hyperuricemia and hypocalcemia are common presentation of tls. case report: we present two cases of spontaneous tls; a rare presentation of tls before cytotoxic chemotherapy. these cases were admitted with presentation of tls without any history of chemotherapy with mediastinal mass in chest x-ray (cxr) and subsequent diagnosis of lymphoblastic lymphoma and t-cell acute lymphocytic leukemia (all). after several hemodialysis sessions, their conditions were improved and they underwent chemotherapy. conclusions: it was found that the presentation of mediastinal mass in cases of lymphoma and acute leukemia might be associated with tls before chemotherapy. in addition, it is important to pay attention to cxr, when we face to a patient with acute renal failure related to tls.