Primary gastric squamous cell carcinoma mistaken for a submucosal tumor

What happened, in summary

A 69-year-old man sought care after losing 3 kg over 2 months. CT showed a large mass between the stomach and pancreas, while endoscopy showed a submucosal-looking gastric mass without an ulcer. Two mucosal biopsies found only chronic inflammation, and the working diagnosis was a gastrointestinal stromal tumor.

During laparoscopic exploration, the mass was found to arise from the back wall of the stomach and invade the pancreas and splenic vessels. To remove it completely, surgeons performed total gastrectomy together with distal pancreatectomy and splenectomy. Frozen-section analysis during surgery unexpectedly showed squamous cell carcinoma.

Final pathology confirmed moderately differentiated squamous cell carcinoma. None of the 19 removed lymph nodes contained cancer, and evaluation found no squamous cell carcinoma in another organ that could explain a metastasis to the stomach. The tumor was therefore diagnosed as primary gastric squamous cell carcinoma. Pathology confirmed Stage III disease.

He recovered without surgical complications and was discharged 7 days later. Adjuvant chemotherapy was recommended, but he declined it. A CT scan 6 months after surgery showed no metastatic disease.