Pure Red Cell Aplasia (PRCA) is an infrequent disease [1,2], which usually presents as hypogenerative normochromic anemia, and is characterized by a significant decrease (including absence) of erythroid precursors [3]. Its etiology can be congenital or acquired, and its correct diagnosis requires exclusion of alternative cases of refractory anemia, so the bone marrow histology plays a crucial role. Myelodisplastic Syndromes (MDS) should always be considered in its differential diagnosis. The

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... of laboratory tools, specifically Flow Cytometry (FCM) is gained importance in the study of malignant and benign hematology pathologies. In MDS, FCM is not yet considered a standard of care, however it provides valuable information [4,5] and there are numerous publications and scores for its usual clinical use (for example Ogata score and RED-score [6,7]). In relation to the rise of FCM in MDS, enormous progress has been made in the description of the erythroid precursors immunophenotype [8-10]. An example of normal erythroid maturation is presented in Figure 1, showing proerythroblasts with immunophenotype CD71+ CD105+ CD117+, basophilic erythroblasts CD71+ CD105+ CD117-, polychromatophilic and orthochromatophilic erythroblasts CD71+ CD105- CD117- distinguishing by size in Forward Scatter (FSC) versus CD36 respectively. Characteristic maturation curve in CD117 versus CD105 analysis evidenced a predominance towards more mature erythroblasts.