Abstract
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.
Keywords
essential thrombocythemia - myeloproliferative neoplasm - Von Willebrand syndrome
