High PD-L1 expression seems to result from the activation of anti-tumor immunity in MCC and has, therefore, been reported as a prognostic marker.4 PD-L1 expression, however, may be heterogeneous, even in the same case.5 6 Although PD-L1 expression reflects the immune status at the time of evaluation, it is still difficult to predict a patient’s outcome on the basis of PD-L1 expression. The gene discussed is CD274; the disease is Merkel cell skin cancer.