Early stage gastric cancer with unusual sarcomatous component and no recurrence after endoscopic submucosal dissection: a case report.

Gastric cancer with sarcomatous changes is relatively rare and often detected at an advanced stage. We report the case of an 82-year-old man with early stage gastric cancer exhibiting an unusual morphology with a polypoid growth of a sarcomatous component arising from a flat area of a well-differentiated adenocarcinoma. He achieved mid-term remission after endoscopic submucosal dissection (ESD). Upon admission, upper gastrointestinal endoscopy revealed a 60-mm flat elevated lesion with a nodule; no lymph node or distant metastasis was noted. He was diagnosed with early stage gastric cancer and underwent ESD. Pathological examination of the nodule revealed carcinomatous cells transitioning to atypical spindle cells and sarcomatous changes, suggesting that the sarcomatous component originated from a gastric-type adenocarcinoma. There was no local recurrence or metastasis at 21 months post-ESD. This is the first report of a case of early stage gastric cancer with a sarcomatous change that achieved mid-term outcome after ESD.