A practical, comprehensive classification for pediatric myelodysplastic syndromes: the CCC system.

PURPOSE: Pediatric myelodysplastic syndromes (MDS) are biologically diverse. The French-American-British (FAB) classification of adult forms of MDS is not always applicable because many pediatric patients do not fit into any of the categories. To circumvent the FAB schema and other flawed formats, the authors developed a practical classification system for childhood MDS.

PATIENTS AND METHODS: The authors analyzed 40 children with MDS diagnosed in Toronto between 1988 and 1998 to test the utility of the classification. Children were classified according to three main features: category, cytology, and cytogenetics.

RESULTS: Using this system the authors were able to classify all 40 patients; about half could not be classified by FAB. Patients could also be longitudinally classified by serial analysis to show progression of disease. Juvenile myelomonocytic leukemia was excluded because of its known myeloproliferative pathogenesis. Chronic myelomonocytic leukemia, which almost never occurs in children, was also omitted. Also excluded were other chronic myeloproliferative disorders and any cytopenias without malignant potential.

CONCLUSIONS: Based on these data, the CCC system appears to have prognostic potential; children with advanced class and cytogenetic abnormalities had a poorer outcome. The authors urge international adoption of this system for uniformity in clinical practice and reporting purposes.