KRT7 and lung cancer: It presents with diffuse involvement of intestinal mucosa, and multiple nodules with or without mucosal ulceration, or appears as solitary volcano-like tumors in the intestine.9 Pathological diagnosis using immunohistochemical staining is a reliable method to differentiate between primary small intestinal tumors and metastasis from the lungs.10 Primary lung cancer usually exhibits CK7+/CK20− immunophenotype while primary intestinal adenocarcinomas are CK7−/CK20+.