A case of endoscopic submucosal dissection of esophageal acantholytic Paget's disease with discontinuously spreading and unclear neoplastic extension.

Background: Paget's disease (PD) is a carcinoma, in which irregular atypical cells with abundant cytoplasm proliferate mainly within the epithelium and is classified into PD occurring in the breast and extramammary Paget's disease (EMPD) occurring outside the breast. Essentially, extramammary PD is reported as a tumor for which it is difficult for surgeons to properly determine the line of resection.

Case presentation: An 83-year-old male was admitted to our hospital because of roughness of the esophageal epithelium during the follow-up examination for a gastric ulcer. A preoperative biopsy revealed squamous cell carcinoma; therefore, endoscopic submucosal dissection (ESD) was performed.

Conclusions: The characteristic feature in this patient was the distribution of tumor cells and, accordingly, the difficulty in identifying the neoplastic distribution. In this patient, the odd distribution and growth pattern of the tumor cells made it difficult for the operator to identify the distribution of the lesion preoperatively.