Abstract • 30

During a 10 year-period (1988-1998) 26 children with MDS (1-15 years of age) were seen at the Pediatric Oncology/Hematology Center in Minsk: RA: 9 pts (=34.7%), RARS: 1 (3.8%), RAEB: 4 (15.3%), RAEBt: 6 (23.1%), CMML: 6 (23.1%) Among CMML patients, one had congenital CMML, 1 monosomy 7, and 1 neurofibromatosis. Hemorrhagic features were seen in 76% of pts; lymphadenopathy, spleno- and hepatomegaly in 34.6%, 53.8%, and 15.3% respectively. 2.6% of RAEB pts had Down syndrome. Virologic tests of bone marrow, peripheral blood, urine and saliva showed antibodies to HSV in 29.7%, to CMV 5.4%, to EBV 4.3%, and to HBV, HCV and HDV in 62.5% respectively. Hematopoietic dysplasia was present in all cell lines: neutropenia with pseudo-Pelger cells and karyorrhexis in 73%, erythroid hyperplasia in 38.5%, and hypoplasia in 34.6%. All pts showed signs of ineffective erythropoiesis with pathologic inclusions, megaloblastoid cells, asynchronous maturation of nuclei and cytoplasm. HbF levels were elevated in 76.9%. Megakaryocytic failure occured in 80.7% of pts. Active macrophages had cell atypias especially in RAEB and RAEBt. A hypocellular bone marrow was seen in 23% of pts, 46% were normocellular, and 31% hypercellular. During the observation period, neoplastic transformation occured in 50% of pts: 46.2% into AML, 7.7% into ALL, 23% into CMML. The mortality rate was 30.7%.