Fulminant Essential Thrombocythemia Associated with Acquired Von Willebrand Syndrome and Bleeding Episodes in a 14-year-old Girl.

BACKGROUND: Essential thrombocythemia is a chronic myeloproliferative neoplasm. It is extremely rare in children below 15 years of age with an estimated annual incidence of only 0.09 per million. Usually, clinical symptoms associated with essential thrombocythemia are mild or absent. CASE: Here, we present the case of a 14-year-old female patient fulminantly presenting with acute symptoms comprising visual impairment, palmar and plantar stabbing pain. Blood count revealed massive thrombocytosis of 2373 × 109/L. Bone marrow morphology showed elevated numbers of mature megakaryocytes. Von Willebrand factor activity/antigen ratio was significantly reduced compatible with an acquired Von Willebrand syndrome associated with high platelet counts. Molecular analyses for driver mutations of myeloproliferative neoplasms including JAK2V617F, CALR and MPL were negative. Acute therapy comprising hyperhydration and oxygen supply complemented by acetylsalicylic acid led to amelioration of symptoms. Medication with hydroxycarbamide maintained a significant reduction of platelet counts but had to be reduced or withheld several times due to neutropenia. Repeated bleeding episodes observed in the course were clearly associated with increases in platelet counts above 1200 × 109/L explained by acquired von Willebrand syndrome. Sixteen months after diagnosis, therapy was switched to pegylated interferon and platelet counts could be stabilized without significant side effects.

Epigenetic silencing of miRNA-9 is associated with HES1 oncogenic activity and poor prognosis of medulloblastoma.

BACKGROUND: microRNA-9 is a key regulator of neuronal development aberrantly expressed in brain malignancies, including medulloblastoma. The mechanisms by which microRNA-9 contributes to medulloblastoma pathogenesis remain unclear, and factors that regulate this process have not been delineated. METHODS: Expression and methylation status of microRNA-9 in medulloblastoma cell lines and primary samples were analysed. The association of microRNA-9 expression with medulloblastoma patients' clinical outcome was assessed, and the impact of microRNA-9 restoration was functionally validated in medulloblastoma cells. RESULTS: microRNA-9 expression is repressed in a large subset of MB samples compared with normal fetal cerebellum. Low microRNA-9 expression correlates significantly with the diagnosis of unfavourable histopathological variants and with poor clinical outcome. microRNA-9 silencing occurs via cancer-specific CpG island hypermethylation. HES1 was identified as a direct target of microRNA-9 in medulloblastoma, and restoration of microRNA-9 was shown to trigger cell cycle arrest, to inhibit clonal growth and to promote medulloblastoma cell differentiation. CONCLUSIONS: microRNA-9 is a methylation-silenced tumour suppressor that could be a potential candidate predictive marker for poor prognosis of medulloblastoma. Loss of microRNA-9 may confer a proliferative advantage to tumour cells, and it could possibly contribute to disease pathogenesis. Thus, re-expression of microRNA-9 may constitute a novel epigenetic regulation strategy against medulloblastoma.