PRF1 and cancer: Many cells were granzyme B positive (500 GrB+ cells/10 HFP figure 8D) suggesting cytotoxic potential, but very few were perforin positive (1 perforin+ cells/10 HFP figure 8E) A right lower lobe lung nodule that was suspicious for cancer was resected from an asymptomatic immunocompetent patient who was exposed to Cryptococcus on Vancouver Island, Canada.