A Case of Gastric Undifferentiated Carcinoma Originally Diagnosed as Gastrointestinal Stromal Tumor

Abstract

Undifferentiated gastric cancer is a rare histological type that exhibits no differentiated components of adenocarcinoma or squamous cell carcinoma. We report the case of a 65-year-old woman with difficult-to-diagnose undifferentiated gastric cancer. After surgical resection, the primary tumor was pathologically suspected to be a gastrointestinal stromal tumor due to marked accumulation of spindle cells. Lymph nodes with metastasis, however, revealed an epithelial component following immunohistochemical staining with CAM5.2 and cytokeratin 8. Eventually, we diagnosed the tumor as undifferentiated carcinoma. Based on our case and the literature review, this tumor can be misdiagnosed because of its rarity, leading to treatment delays. Both the surgeon and pathologist need to consider undifferentiated carcinoma whenever they encounter unusual pathological findings.