Cutaneous blastic plasmacytoid dendritic cell neoplasm occurring after spontaneous remission of acute myeloid leukemia: a case report and review of literature.

Spontaneous remission of acute myeloid leukemia (AML) is an extremely uncommon event. The etiology is associated with infection, blood transfusion or granulocyte colony-stimulating factor therapy, which trigger immune responses to exert an antileukemic effect. The remission is usually temporary and followed by rapid relapse. However, we present a case of a 42-year-old man with spontaneous remission of AML-M5a, who did not relapse but developed a rare and aggressive lymphoma, named cutaneous blastic plasmacytoid dendritic cell neoplasm (BPDCN). The neoplasm cells are positive for CD4, CD56, CD43, CD45, and CD123, but negative for other lineage-specific markers. To our knowledge, this is the first report of BPDCN occurring after spontaneous remission of AML, although it has been observed that some BPDCN could shift to myeloid leukemia. Occurrence of the two diseases is more than a coincidence. Discovery of such cases may shed further light on the inner connection between BPDCN and myeloid disorders.