The online version of this article has a Supplementary Appendix. BackgroundBlastic plasmacytoid dendritic cell neoplasm is a rare malignancy that typically follows a highly aggressive clinical course in adults, whereas experience in children with this disease is very limited. Design and MethodsThis retrospective study analyzed the pathological and clinical findings of nine cases of blastic plasmactyoid dendritic cell neoplasm presenting in patients under the age of 18 years who were reviewed at our institution. We also identified 20 well-documented additional pediatric cases in the literature. ResultsIn the combined analysis, the overall survival rate among the 25 patients with available followup, all having received chemotherapy, was 72% (follow-up ranging from 9 months to 13 years, with a median of 30 months). The event-free survival rate was 64%. Nine patients were alive 5 years after the original diagnosis, although only three of them had undergone hematopoietic stem cell transplantation -one in first complete remission and two in second remission. Of the seven patients who lacked cutaneous disease at presentation, 100% survived, including five who were alive more than 5 years after diagnosis, although only two had undergone stem cell transplantation. Among the 18 patients who presented with cutaneous disease and for whom follow-up data were available, only 11 survived (61%). Detailed immunophenotypic characterization and clinical features of all cases are presented. Unexpectedly, three of four cases of blastic plasmacytoid dendritic cell neoplasm tested showed focal positivity for S-100. S-100 was negative in 28 cases of acute myeloid leukemia evaluated for this marker. ConclusionsIn contrast to adult cases, in which long-term survival depends on stem cell transplantation in first complete remission, blastic plasmacytoid dendritic cell neoplasms in children are clinically less aggressive. Treatment with high-risk acute lymphoblastic leukemia-type chemotherapy appears to be effective, and stem cell transplantation may be reserved for children who relapse and achieve a second remission. Outcomes were more favorable in cases that lacked cutaneous disease at presentation, although a comparison of cutaneous and non-cutaneous cases might be confounded by differences in treatment regimens. Focal expression of S-100 may be seen in concert with other markers of plasmacytoid dendritic cells.Key words: blastic plasmacytoid dendritic cell neoplasm, CD4 + /CD56 + hematodermic neoplasm, pediatric, acute myeloid leukemia, acute lymphoblastic leukemia, stem cell transplant, S-100, immunophenotyping, dendritic cells.Citation: Jegalian AG, Buxbaum NP, Facchetti F, Raffeld M, Pittaluga S, Wayne AS, and Jaffe ES. Blastic plasmacytoid dendritic cell neoplasm in children: diagnostic features and clinical implications. Haematologica 2010;95(11):1873-1879 doi:10.3324/haematol.2010

Boys with haemophilia are now encouraged to exercise and take part in physical activities, but actual measures of time spent in active participation is lacking. The aim of this study was to obtain an objective measure of daily physical activity in boys with haemophilia as compared with healthy controls. The study also aimed to ascertain the social and cognitive factors associated with exercise in this population. Seventeen patients (aged 11-18 years) with haemophilia were studied and compared with 44 healthy controls (aged 10-16.5 years). Physical activity was measured by accelerometry. Psychosocial correlates were assessed using validated questionnaires. Measured physical activity levels in subjects with haemophilia were slightly higher than for the control group. Both groups spent 70% of the day inactive, with similar proportions of time in moderate and vigorous activity. Subjects with haemophilia had a favourable self-image and similar levels of anxiety as peers without a bleeding disorder. Self-efficacy scores were lower than for controls suggesting increased sensitivity to barriers and lack of acceptance of alternatives. Health beliefs did not influence physical activity, but a negative correlation of time spent in high or vigorous activity with scores for support-seeking was observed. The data demonstrate that in the appropriate social environment and with medical support, patients with haemophilia may be as physically active as their peers without a bleeding disorder. Further investigation into the psychosocial barriers of physical activity in patients with haemophilia is needed to more effectively encourage healthy behaviours.

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Graft-versus-host disease (GVHD) is a prominent barrier to allogeneic hematopoietic stem cell transplantation (AHSCT). Definitive diagnosis of GVHD is invasive, and biopsies of involved tissues pose a high risk of bleeding and infection. T cells are central to GVHD pathogenesis, and our previous studies in a chronic GVHD mouse model showed that alloreactive CD4+ T cells traffic to the target organs ahead of overt symptoms. Because increased glycolysis is an early feature of T-cell activation, we hypothesized that in vivo metabolic imaging of glycolysis would allow noninvasive detection of liver GVHD as activated CD4+ T cells traffic into the organ. Indeed, hyperpolarized 13C-pyruvate magnetic resonance imaging detected high rates of conversion of pyruvate to lactate in the liver ahead of animals becoming symptomatic, but not during subsequent overt chronic GVHD. Concomitantly, CD4+ T effector memory cells, the predominant pathogenic CD4+ T-cell subset, were confirmed to be highly glycolytic by transcriptomic, protein, metabolite, and ex vivo metabolic activity analyses. Preliminary data from single-cell sequencing of circulating T cells in patients undergoing AHSCT also suggested that increased glycolysis may be a feature of incipient acute GVHD. Metabolic imaging is being increasingly used in the clinic and may be useful in the post-AHSCT setting for noninvasive early detection of GVHD.