Fig. 3From: Perforation of small intestinal metastasis of lung adenocarcinoma treated with pembrolizumab: a case reportPathological examination and immunohistochemical stain for thyroid transcription factor 1 (TTF-1). a The right side of the picture was the perforated site, and tumor cells and fibrosis were observed throughout the whole layer (× 40). b There were tumor cells with high degree of degeneration and necrosis change in the perforation site (× 100). The pathological response for the efficacy of pembrolizumab was grade 1b (Japanese Classification of the Colorectal Carcinoma, seventh edition). c The tumor cells showed TTF-1 expression in immunohistochemical stainBack to article page