Merkel cell carcinoma (MCC) and small cell lung cancer (SCLC) share quite distinct similarities such as almost undistinguishable histological presentation (fig 1a,b) and highly aggressive biological behaviour with high rates of metastasis and poor survival rates.1 2 While tobacco smoking and genetic susceptibility have been identified as risk factors for SCLC,3 4 sun exposure and immunosuppression are the main risk factors for MCC.1 In January 2008, a new virus, called Merkel cell polyomavirus (MCPyV), was desribed by Feng et al as a likely causative agent of MCC, proving monoclonal MCPyV–genome integration in 8 of 10 MCCs.5 Since then these findings have been reproduced by several groups.6 7