Prospective validation of the provisional entity of refractory cytopenia of childhood, proposed by the World Health Organization.

In 2008, the World Health Organization proposed a new entity of childhood myelodysplastic syndrome (MDS), which was referred to as refractory cytopenia of childhood (RCC). However, whether this morphological classification reflects clinical outcomes remains unclear. We performed a prospective evaluation of bone marrow morphology in 252 children with acquired bone marrow failure between 2009 and 2013. Of 252 patients, 63 were diagnosed with aplastic anaemia (AA), 131 with RCC without multilineage dysplasia (RCC-w/o-MLD) and 58 with RCC with MLD (RCC-MLD). One patient with AA, three with RCC-w/o-MLD and nine with RCC-MLD presented with chromosomal abnormalities at diagnosis (P = 0·001). The response rates to immunosuppressive therapy (IST) at 6 months and the cumulative incidence of clonal evolution at 5 years did not significantly differ among the three groups. A multivariate analysis revealed that the morphological classification of RCC-MLD was a significant risk factor for secondary graft failure after haematopoietic cell transplantation (HCT) (P = 0·003). In view of these findings, RCC could be divided into two categories, RCC-w/o-MLD and RCC-MLD, because children with this condition exhibited a distinct morphology, frequent chromosomal abnormalities at diagnosis and a high frequency of secondary graft failure after HCT.

[A case of Burkitt lymphoma with multifocal bone invasion].

A 12-year-old boy admitted to a local hospital with fever, migratory arthralgia, and periosteal reaction on X Ray. He was transferred to our hospital because magnetic resonance imaging scan of his whole body showed multiple abnormal signals in bones. Laboratory findings on admission showed the increased erythrocyte sedimentation rate, uric acid, lactate dehydrogenase, alkaline phosphatase, C-reactive protein, immunoglobulin G, hemolytic complement activity and soluble interleukin-2 receptor. Peripheral blood and bone marrow examination did not show any abnormality. The clinical appearance of his condition suggested the diagnosis of chronic recurrent multifocal osteomyelitis (CRMO). He was treated with steroid, however his fever and bone pain continued. A bone and bone marrow biopsy was performed and the results of histopathology showed precursor-B acute leukemia/lymphoma. His bone pain relapsed after the chemotherapy for ALL. Finally, blast cells resembling L3 morphology were detected in the peripheral blood. The reevaluated bone marrow was predominantly replaced with Burkitt like lymphoblasts. He was diagnosed with Burkitt lymphoma by further specific examination.

[Bone marrow findings of childhood aplastic anemia: analyses of 140 cases by central reviewers].

The revised WHO classification proposed the term "refractory cytopenia of childhood (RCC)" for children with myelodysplastic syndrome (MDS) with a low blast count. The differential diagnosis between RCC and aplastic anemia (AA) is challenging, especially when bone marrow is hypoplastic and there is no detectable chromosomal abnormality. To reveal the difference between AA and RCC with respect to the clinical and biological features, we retrospectively reviewed the bone marrow smears of 140 patients registered for childhood AA-97 study, which were classified into three groups as follows; the AA group was defined as having no morphologically dysplastic changes; the AA-RCC borderline group was defined as having <10% dysplastic changes in the erythroid lineage only; and the RCC group was defined as having dysplastic changes in more than two cell lineages or >10% in a single cell lineage. The patients were classified into the AA group (n=96, 69%), AA-RCC borderline group (n=20, 14%) and RCC group (n=24, 17%). Most of the patients in the AA group were classified as having very severe disease, whereas most of the patients in the RCC group were classified as non-severe disease. Only 2 patients in the AA group developed acute myeloid leukemia. The response rate to immunosuppressive therapy did not differ among the 3 groups. To demonstrate whether the two diseases are truly different entities, it is necessary to compare molecular backgrounds between the AA and RCC groups.