CD8A and Merkel cell skin cancer: A significantly improved MCC-specific survival was seen in patients with an increased stain area fraction of CD8 lymphocytes (HR = 0.70; 95% CI= 0.57–0.87; p = 0.001) and with a positive viral status (HR = 0.47; 95% CI = 0.22–1.00; p = 0.05).