Merkel cell carcinoma from 2008 to 2012: reaching a new level of understanding.

Merkel cell carcinoma (MCC) is a rare primary cutaneous carcinoma of the skin who has high aggressiveness, high risk of locoregional and distant spread, a mortality rate considerably higher than that of cutaneous melanoma and a poor survival. Its incidence has increased during the past twenty years. The studies published from 2008 to early 2012 have introduced interesting changes in the understanding of its epidemiology, pathogenesis and consequently in the diagnostic codes and the therapeutic approach.