Fatal submucosal invasive gastric adenosquamous carcinoma detected at surveillance after gastric endoscopic submucosal dissection.

An 80-year-old man was under annual surveillance esophagogastroduodenoscopy after endoscopic submucosal dissection (ESD) for early gastric cancer (EGC). Two years after the initial ESD, a 0-IIc type metachronous EGC lesion, 8 mm in size, without an ulcer scar, was found in the gastric antrum. The estimated tumor depth was up to the mucosa, and biopsy revealed well and poorly differentiated adenocarcinoma. ESD was performed for this lesion and en bloc resection with negative margins was achieved. Histopathological examination revealed an adenosquamous carcinoma 8 mm in size invading the deep submucosal layer (1600 µm), with lymphovascular invasion, consistent with the diagnosis of non-curative resection. Additional gastrectomy was recommended for this patient; however, two months after the ESD, preoperative computed tomography revealed multiple liver metastases, and the patient was considered as an unsuitable candidate for surgical resection. Systemic chemotherapy was therefore started; however, the patient died of gastric cancer 27 mo after the second ESD. Early gastric adenosquamous carcinoma localized to the mucosa and submucosa is extremely rare and its clinical behavior is not well known. The present report is very significant in that it underscores the distinct possibility of gastric adenosquamous carcinoma being very aggressive and fatal even when detected at an early cancer.