An unusual non‑metastatic, mismatch repair‑deficient primary gastric squamous cell carcinoma presenting as a large, exophytic, bleeding tumor: A case report.

Primary gastric squamous cell carcinoma (GSCC) is an extremely rare malignancy with a poor prognosis. Despite the improved knowledge regarding its pathogenesis and biology, the treatment options remain limited. The present study reported on the unique case of a mismatch repair-deficient (dMMR) primary GSCC in a 79-year-old woman reporting fatigue and symptoms of upper gastrointestinal tract bleeding. Physical examination revealed abdominal pain at palpation. Gastroscopy revealed a large, exophytic, bleeding tumor. Medical imaging confirmed a mushroom-like polyp in the lumen of the stomach, with no signs of disease spread. Total gastrectomy and D2 lymphadenectomy were performed. Pathological examination of the post-operational material confirmed a well-differentiated SCC invading the mucosa, submucosa and muscle layer. There were no signs of dissemination observed in any of the 32 excised lymph nodes. Notably, according to the last follow-up, the patient remains well, supporting the 5-year GSCC survival rate statistics. To the best of our knowledge, this is the first such GSCC case reported in the Surgical Oncology Outpatient Clinic (Copernicus Memorial Hospital, Lodz, Poland) and these findings add to the limited data on GSCC. Although this is a very rare condition, it should always be considered during the process of diagnosis of gastric tumors.