Myelodysplastic and myeloproliferative disorders of childhood: A study of 167 patients

Myelodysplastic syndromes (MDS) and myeloproliferative syndromes (MPS) of c hildhood are a heterogeneous group of clonal disorders of hematopoiesis wit h overlapping clinical features and inconsistent nomenclature. Although a n umber of genetic conditions have been associated with MDS and MPS, the over all contribution of inherited predispositions is uncertain. We report a ret rospective study examining clinical features, genetic associations, and out comes in 167 children with MDS and MPS. Of these patients, 48 had an associ ated constitutional disorder. One hundred one patients had adult-type myelo dysplastic syndrome (A-MDS), 60 had juvenile myelomonocytic leukemia (JMML) , and 6 infants with Down syndrome had a transient myeloproliferative syndr ome (TMS). JMML was characterized by young age at onset and prominent hepat osplenomegaly, whereas patients with AMDS were older and had little or no o rganomegaly. The most common cytogenetic abnormalities were monosomy 7 or d el(7q) (53 cases); this was common both in patients with JMML and those wit h A-MDS. Leukemic transformation was observed in 32% of patients, usually w ithin 2 years of diagnosis. Survival was 25% at 16 years. Favorable prognos tic features at diagnosis included age less than 2 years and a hemoglobin F level of less than 10%. Older patients tended to present with an adult-typ e MDS that is accommodated within the French-American-British system. In co ntrast, infants and young children typically developed unique disorders wit h overlapping features of MDS and MPS. Although the type and intensity of t herapy varied markedly in this study the overall outcome was poor except in patients with TMS. (C) 1999 by The American Society of Hematology.