1. ¹Department of Pediatrics, Skejby Hospital, Aarhus, Denmark
2. ²University Children's Hospital, Freiburg, Germany
3. ³Institute of Child Health, London, UK
4. ⁴Institute of Pathology, Erlangen, Germany
5. ⁵University of Rochester Cancer Center, Rochester, USA, NY
6. ⁶Institute of Pathology, Odense University Hospital, Odense, Denmark
7. ⁷Department of Pathology, Vanderbilt University, Nashville, TN, USA

Correspondence: H Hasle, Department of Pediatrics, Skejby Hospital, 8200 Aarhus N, Denmark; Fax: +45 8949 6023; E-mail: hasle@dadlnet.dk

Received 18 April 2002; Accepted 7 August 2002.

Abstract

Myelodysplastic and myeloproliferative disorders are rare in childhood and there is no widely accepted system for their diagnosis and classification. We propose minimal diagnostic criteria and a simple classification scheme which, while based on accepted morphological features and conforming with the recent suggestions of the WHO, allows for the special problems of myelodysplastic diseases in children. The classification recognizes three major diagnostic groups: (1) juvenile myelomonocytic leukemia (JMML), previously named chronic myelomonocytic leukemia (CMML) or juvenile chronic myeloid leukemia (JCML); (2) myeloid leukemia of Down syndrome, a disease with distinct clinical and biological features, encompassing both MDS and AML occurring in Down syndrome; and (3) MDS occurring both de novo and as a complication of previous therapy or pre-existing bone marrow disorder (secondary MDS). The main subtypes of MDS are refractory cytopenia (RC) and refractory anemia with excess of blasts (RAEB). It is suggested retaining the subtype of RAEB-T with 20–30% blasts in the marrow until more data are available. Cytogenetics and serial assessments of the patients are essential adjuncts to morphology both in diagnosis and classification.