Extramedullary leukemia in children with acute myeloid leukemia: A population-based cohort study from the Nordic Society of Pediatric Hematology and Oncology (NOPHO).
BACKGROUND
The prognostic significance of extramedullary leukemia (EML) in childhood acute myeloid leukemia is not clarified.


METHODS
This population-based study included 315 children from the NOPHO-AML 2004 trial.


RESULTS
At diagnosis, 73 (23%) patients had EML: 39 (12%) had myeloid sarcoma, 22 (7%) had central nervous system disease, and 12 (4%) had both. EML was associated with young age (median age: 2.6 years), a high white blood cell count (median: 40 × 109/l), M5 morphology (40%), and 11q23/MLL (KMT2A) rearrangements (34%). No patient received involved field radiotherapy. Five-year event-free survival did not differ significantly between the EML and the non-EML patients (54% vs. 45%, P = 0.57), whereas 5-year overall survival (OS) was significantly lower in the EML group (64% vs. 73%, P = 0.04). The risk of induction death was significantly higher for EML patients (8% vs. 1%, P = 0.002). There was a trend toward a lower risk of relapse for EML patients (5-year cumulative incidence of relapse 33% vs. 49%, P = 0.16). Traumatic lumbar puncture did not adversely affect survival in this cohort.


CONCLUSIONS
EML was associated with increased risk of induction death impacting the OS. No patients relapsed at the primary site of the myeloid sarcoma despite management without radiotherapy.
Department of Pediatrics, Aarhus University Hospital, Aarhus, Denmark.
Heidi Kristine
HK
Støve
Department of Pediatrics, Aarhus University Hospital, Aarhus, Denmark.
Julie Damgaard
JD
Sandahl
Department of Pediatrics, Institution for Clinical Sciences, Queen Silvia Children's Hospital, Gothenburg, Sweden.
Jonas
J
Abrahamsson
Department of Pediatrics, Aarhus University Hospital, Aarhus, Denmark.
Peter H
PH
Asdahl
Department of Medical Biosciences and Genetics, Umeå University Hospital, Umeå, Sweden.
Erik
E
Forestier
Department of Pediatrics, Hong Kong Pediatric Hematology & Oncology Study Group, Queen Mary Hospital, Hong Kong, China.
Shau-Yin
SY
Ha
Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
Kirsi
K
Jahnukainen
Department of Pediatrics, Landspitalinn, Reykjavik, Iceland.
Ólafur G
ÓG
Jónsson
Department of Pediatrics and Adolescent Medicine, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
Birgitte
B
Lausen
Department of Woman's and Children's Health, Uppsala University, Uppsala, Sweden.
Josefine
J
Palle
Department of Pediatric Medicine, Oslo University Hospital, Oslo, Norway.
Bernward
B
Zeller
Department of Pediatrics, Aarhus University Hospital, Aarhus, Denmark.
Henrik
H
Hasle
D000293:Adolescent; D002452:Cell Count; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007223:Infant; D015470:Leukemia, Myeloid, Acute / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D008297:Male; D011379:Prognosis; D012008:Recurrence; D013129:Spinal Puncture; D016896:Treatment Outcome
acute myeloid leukemia; central nervous system disease; children; chloroma; extramedullary leukemia