Peer Review Report For: Case Report: Primary pure clear cell gastric carcinoma [version 1; peer review: 2 approved with reservations]

Clear cell carcinoma has been described in numerous anatomic sites, but the renal location is the most frequent. Its occurrence in the stomach is exceptional. Here, we report the case of a 51-year-old woman who presented with epigastric pain of four months. The upper gastrointestinal endoscopic examination revealed a polypoid tumor of the greater curvature of the stomach. Biopsies showed a poorly differentiated carcinoma with a signet-ring cell component. The CT scan revealed a polypoid mass of the vertical part of the greater gastric curvature. There was no renal lesion. A distal subtotal gastrectomy was performed, and the post-operative course was uneventful. The gross exam showed a 6.5 cm, polypoid ulcerated tumor of the antrum. Histological analysis showed a clear cell gastric carcinoma. The immunohistochemical study, performed to rule out a metastasis from renal carcinoma, showed that tumor cells didn’t express CD10 and vimentin. We therefore retained the diagnosis of a primary gastric clear cell carcinoma. Pure primary clear cell carcinomas of the stomach are exceedingly rare and are associated with a poor prognosis. Immunohistochemistry is the cornerstone of the diagnosis of these tumors to rule out metastases from a renal clear cell carcinoma.