Invasion of poorly differentiated adenocarcinoma to the deep muscularis mucosae may be an indicator of lymph node metastasis in Barrett's esophageal cancer.

A 48-year-old man underwent endoscopic submucosal dissection (ESD) for a protruding lesion with a preoperative diagnosis of superficial Barrett's esophageal adenocarcinoma. Histopathological examination of the resected specimen showed invasion of poorly differentiated adenocarcinoma to the deep muscularis mucosa, although the predominant histology was differentiated-type and there was no lymphovascular infiltration. Additional esophagectomy with nodal dissection was conducted for possible remnant tumor cells after informed consent was given, and uncovered the presence of a metastatic lymph node. Caution is advised in the treatment of Barrett's esophageal adenocarcinoma with invasion of poorly differentiated tumor cells into the deep muscularis mucosae.