Comparison of two new classifications for pediatric myelodysplastic and myeloproliferative disorders.

BACKGROUND: The category, cytology, cytogenetics (CCC) system for myelodysplastic syndrome (MDS) and the pediatric WHO system for MDS/myeloproliferative disorder (MPD) have recently been proposed to characterize these diseases in pediatrics.

OBJECTIVE: We compare the CCC and pediatric WHO systems against each other and against the French, American, British (FAB) and adult WHO classifications in order to determine which more accurately classifies these diseases and predicts outcome.

METHODS: An 18-year retrospective review identified patients less than 18 years of age meeting CCC and/or pediatric WHO criteria for the diagnosis of MDS or MPD. Resolution, stability, progression, and death in the subcategories of each system were compared.

RESULTS: Twenty-eight patients were included in the study. Pediatric WHO: 17 patients met criteria, 10 died. Eight developed acute myelogenous leukemia (AML) (seven died), one juvenile myelomonocytic leukemia (JMML) (died), one chronic myelomonocytic leukemia (CMML) (currently in relapse), two died of complications, two responded to BMT, three have stable disease, one resolved. Eleven patients were not classifiable by the pediatric WHO system, one of which progressed to AML and died. CCC: 26 patients met criteria, 9 died. Nine developed AML (8 died), 1 died of complications, 10 responded to treatment (BMT and/or chemotherapy). Four are stable without treatment, two resolved. Two patients with MPD were not classifiable by the CCC system.

CONCLUSIONS: Both the pediatric WHO and CCC systems are better able to classify MDS in children than the adult WHO and FAB classifications. The pediatric WHO system is more exclusive. Children meeting these criteria are more likely to progress to AML or death. The restrictive nature of the pediatric WHO system was unable to classify one case of fatal MDS. The CCC system is more inclusive and can stratify patients into a neutral or poor prognosis based upon outcome. However, the CCC system ignores those diseases with a myeloprolifferative component. This resulted in two cases of MPD that were unclassifiable by the CCC system. One of these patients died, the other is currently in relapse.