Tumoral aspects of plasmacytoid dendritic cells: what do we know in 2009?

Plasmacytoid dendritic cell (PDC) is a Th2-type dendritic cell precursor. It is an important professional effector cell characterized by its capacities to produce large amount of alpha interferon and to differentiate into dendritic cell. PDCs are scarce in normal condition. They circulate in the blood as veiled cells and enter the lymph node and mucosal site in response to immune stimulation. Besides the recent and wide-open field of the implication of PDCs in inflammatory diseases and in the microenvironment of solid or lymphoid tumours it has also been observed that PDCs can also be tumoral cells. In this paper, the authors present the different tumours thought to be originating from tumoral PDCs. To date, two kinds of tumoral conditions are recognized: the so-called PDCs proliferations in patients with myeloid disorders and the blastic plasmacytoid dendritic cell neoplasm. These two entities are exposed and discussed.