Fig. 2

PD-1 and PD-L1 expression in Merkel cell carcinoma primary tumor from the right upper scapula. Legend: a, b: PD-1 shows patchy expression in tumor-associated lymphocytes. c, d: There is no significant PD-L1 expression in tumor cells. Background inflammatory cells express patchy PD-L1, predominantly in larger cells consistent with histiocytes (yellow arrowheads). Magnification 40x (a, c) or 400x (b, d)