Distinction of 2 Different Primary Merkel Cell Carcinomas in 1 Patient by Merkel Cell Polyomavirus Genome Analysis

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine skin carcinoma.¹ Owing to the recent isolation of a new human polyomavirus from MCC called Merkel cell polyomavirus (MCV),² this malignancy has attracted much attention. Meanwhile, several groups have confirmed that MCV is detectable in 70% to 80% of MCC. Herein, we report how sequencing of the MCV genome may help to discern between delayed metastasis and multiple primary MCCs.