Within the differential diagnosis, there is an entity known as proliferation of mature plasmacytoid dendritic cells associated with myeloid neoplasms (such as chronic myelomonocytic leukemia, myelodysplasia, and acute leukemias) characterized by irregular aggregates in bone marrow or lymph nodes of phenotypic plasmacytoid dendritic cells and morphologically similar to normal, with a Ki-67 proliferation index of less than 10% and almost always CD56 negative [3]. This evidence concerns the gene MKI67 and chronic myelomonocytic leukemia.