RESUMO
Tumor lysis syndrome (TLS) is a severe complication of chemotherapy brought about by the rapid destruction of tumor cells. TLS is usually diagnosed by elevation of intracellular enzymes and no specific abnormality is found in complete blood counts. We present a 22-year-old woman with acute lymphoblastic leukemia (ALL) complicated with TLS, in whom elevation of leukocytes and platelet count was observed due to fragmented leukocytes. The day after initiating chemotherapy, a rapid increase in intracellular enzymes was found and a diagnosis of TLS was made. Her leukocyte and platelet counts increased from 8,400/ml to 42,600/ml. and from 43,000/ml to 231,000/ml, respectively. Many fragmented leukocytes were found in her peripheral blood picture. The automated hematology analyzer counted these fragments as leukocytes or platelets, with resulting pseudo-leukocytosis and pseudo-thrombocytosis. When evaluating laboratory data of TLS, it is necessary to focus on the peripheral blood picture to avoid misunderstanding the blood cell counts.