RESUMEN
Deletion of the long arm of chromosome 20 (del 20q) has been observed in patients with myelodysplastic syndrome (MDS) or myeloid malignancies. We experienced an MDS female case of del 20q accompanied by clusters of plasmacytic cells in bone marrow. Her bone marrow cells showed morphological abnormalities in three lineages and the chromosomal abnormality of 46, XX, del (20) (q11.2q13.3). Although the percentage of plasma cells was low in free cells, such cells showed nuclear abnormalities. In bone marrow clots, we also observed clusters of anti-CD38 and anti-CD138 antibody-positive cells. According to the FAB or WHO classification, the diagnosis was unclear. Therefore, we were obliged to term this case as MDS with plasma cell dysplasia. This patient was considered to be a rare case of MDS related to abnormalities in myeloid and B-lymphoid cells.