Extramedullary infiltration at diagnosis and prognosis in children with acute myelogenous leukemia

Abstract

Background: Extramedullary infiltration (EMI) is an occasional clinical symptom in childhood acute myelogenous leukemia (AML), but there is considerable controversy regarding the prognostic significance of EMI in AML.

Procedure: We evaluated the frequency and prognostic significance of EMI at diagnosis of AML in children.

Results: Of 240 cases of de novo AML excluding children with Down syndrome and acute promyelocytic leukemia, 56 (23.3%) showed EMI at diagnosis. Patients with EMI had a higher initial WBC count and a higher proportion of M4/M5 morphological variants. The complete remission rate following induction chemotherapy was lower in patients with EMI. However, the overall survival and event-free survival did not differ between patients with and without EMI. A detailed analysis showed that patients with EMI with a WBC count at diagnosis of over 100 x 10(9)/L or infiltration into the central nervous system are likely to have a poor prognosis.

Conclusions: CNS leukemia and EMI together with a WBC count of >100 x 10(9)/L at diagnosis of AML are high risk factors for relapse, and alternative treatment approaches for patients with these characteristics should be explored.