Myelodysplastic Syndrome Developing Presacral Extramedullary Hematopoiesis with Atypical MRI Findings.

A 64-year-old woman was diagnosed to have refractory cytopenia with multilineage dysplasia (RCMD) including an increased number of sideroblasts in the bone marrow (BM). Computed tomography (CT) revealed a presacral mass which showed iso- or high-intensity signals according to T1-weighted and hypo-intensity signals on T2-weighted magnetic resonance imaging (MRI). CT-guided biopsy revealed the presence of hematopoietic tissue with features that correlated with the BM findings. While the formation of extramedullary hematopoiesis in the presacral area is rare, it is important to differentiate it from other parasacral tumors even though such differentiation is often difficult. This patient demonstrated atypical MRI signals possibly due to an increase in the cellular iron content of the erythroid precursors.