Fig. 1. (A) The initial biopsy specimen obtained at a local clinic shows atypical cells in an erosive background, which are suspicious of carcinoma (hematoxylin & eosin [H&E] stain, ×200). (B) The second biopsy specimen also shows a few atypical cells of indeterminate malignant potential (H&E stain, ×200). The patient provided written informed consent for the publication and use of his images.

Fig. 2. (A) Conventional endoscopy show a 5-mm-sized reddish depressed lesion in the mid-esophagus, 30 cm below the upper incisor teeth. (B) The lesion is unstained by Lugol’s iodine solution. (C, D) Narrow band imaging shows tortuous, irregular intrapapillary capillary loops, and these features are apparently visualized with a near focus mode. The patient provided written informed consent for the publication and use of his images.

Fig. 3. (A) Markings around the lesion. (B, C) The tumor was completely resected by endoscopic submucosal dissection. (D) Gross finding show a 5-mm-sized Lugol-unstained lesion with clear margins. The patient provided written informed consent for the publication and use of his images.

Fig. 4. (A) Tumor cells demonstrate a mixed expanding and infiltrative pattern consisting of a variable admixture of squamoid and mucous cells with scattered intermediate-type cells (hematoxylin & eosin [H&E] stain, ×200). (B) In some area, aggregates of mucin-producing cells with an unusual pattern can be observed (H&E stain, ×200). (C) p40 staining highlights the squamous component (×200). (D) CK7 staining focally highlights the mucinous cells (×200). (E) Mucicarmine staining demonstrates the mucin-producing cells with intracytoplasmic mucin (×200). The patient provided written informed consent for the publication and use of his images.