KRT20 and acinar lung adenocarcinoma: Positive cytoplasmic staining of CK20 was observed in all (100%) the 10 primary colorectal cancer samples and in 16 (84.2%) of the 19 lung metastasis of colorectal cancer samples, but in none of the primary lung acinar adenocarcinoma samples (Figure 1G, H, and 1I; Table 1).