A case of myelodysplastic syndrome with marked eosinophilia showing favorable prognosis

Myelodysplastic syndrome (MDS) with eosinophilia is a rare condition and has yet to be classified under the 2008 World Health Organization classification. However, reports have described the prognostic significance of chronic persistent eosinophilia in MDS. Here, we report a case of a 67-year-old woman who was admitted to the hospital in July 2007 with generalized weakness, dizziness, and dyspnea on exertion persisting for 5 years. In the initial investigation, eosinophilia (22.1%) in peripheral blood and an increased proportion of eosinophils (5.6%) in normocellular bone marrow with dysplastic megakaryocytes and erythroid cells were noted. Eosinophilia was continuously detected during follow-up over 3 years. In a second bone marrow examination in August 2010, hypercellular bone marrow with similar features was observed. These findings led to the diagnosis of MDS with chronic persistent eosinophilia. To increase awareness of the prognostic significance of MDS with chronic eosinophilia, here we report a slow-progressing case of MDS with chronic persistent eosinophilia lasting over 6 years.