A 32 year-old male patient was admitted to our hospital because of abdominal
tumor. The examination on admission showed massive
splenomegaly and
esophageal varices although peripheral blood cell counts were within normal limits. Exploratory
laparotomy was performed with the diagnosis of
portal hypertension and revealed the multiple
thrombus formations in the splenic vein and the extramedullary hematopoietic findings in the spleen by the microscopic examination. In vitro colony forming assay showed the formation of spontaneous erythroid colonies in cultures of progenitor cells (from peripheral blood mononuclear cells) in
erythropoietin-poor medium. Increasing
thrombocytosis was observed immediately after
splenectomy, and
hemorrhagic diathesis of
nasal bleeding and gastrointestinal
bleeding were also detected. The analysis of plasma
von Willebrand factor (vWF) revealed the decrease of
ristocetin cofactor activity and the lack of large multimeric components of vWF. These abnormal findings observed after
splenectomy led to recovery through the administration of
busulfan with the improvement of
thrombocytosis. Accordingly, the course of the disease clearly indicated it to be the
essential thrombocythemia represented as portal vein
thrombosis and in latent form with normal cell counts in peripheral blood at the time of diagnosis, and subsequently, to develop into a full-blown form associated with acquired von Willebrand syndrome following
splenectomy.