RESUMEN
INTRODUCTION: Tumor lysis syndrome is an oncologic emergency resulting from rapid and massive tumor cell death that may lead to serious clinical complications including acute kidney injury and cardiac arrest. Tumor lysis syndrome most often occurs after the initiation of cytotoxic therapy in patients with high-grade lymphomas and acute lymphoblastic leukemia. CASE REPORT: We present a first case of patient with chemotherapy-resistant chronic lymphocytic leukemia and small lymphocytic lymphoma who developed tumor lysis syndrome upon treatment with ibrutinib (Imbruvica), a novel tyrosine kinase inhibitor. MANAGEMENT AND OUTCOME: The patient showed dramatic improvement in kidney function, uric acid and phosphorus after discontinuation of ibrutinib and a short course of rasburicase (recombinant urate oxidase), and two haemodialysis treatments. DISCUSSION: Clinicians should be aware of this serious side effect and closely monitor kidney function in patients treated with this oral kinase inhibitor.