Pernicious anemia: a myelodysplastic syndrome look-alike.

Severe cytopenias (anemia, thrombocytopenia, neutropenia or any combination of these) are common causes of ER visits and hospital admissions. In adults, the etiology of cytopenias has a broad differential diagnosis including vitamin and mineral deficiencies, autoimmune conditions, infections, bone marrow failure disorders, or malignancies. We present a case of severe anemia and thrombocytopenia who was initially diagnosed with myelodysplastic syndrome (MDS) based on the results of a bone marrow biopsy. However, subsequent workup revealed that she had B12 deficiency secondary to pernicious anemia. This case highlights how performing a bone marrow biopsy without investigating secondary causes of cytopenia and bone marrow dysplasia can lead to a false diagnosis of MDS. Confirmation of the appropriate diagnosis spared the patient emotional trauma and unnecessary treatment with hypomethylating agents.