KRT20 and lung adenocarcinoma: Tan et al (1998) reported a series of 10 cases with lung adenocarcinomas, and nine cases of colon adenocarcinoma metastatic to the lung. Biopsies from all 10 patients with lung primaries stained CK7+/CK20−, while all metastatic lesions from the colon were CK7−/CK20+ (Tan et al, 1998).