Genetic Alterations And Expression Of Epithelial-Mesenchymal Transition Markers In Gastric Sarcomatoid Carcinoma: Report Of A Case And Review Of Literature

Sarcomatoid carcinoma arising from stomach is rare and its molecular alterations are largely unknown. We reported one case of gastric sarcomatoid carcinoma in a 69-year-old man who was hospitalized for upper abdominal discomfort and melena. Endoscopic examination revealed an infiltrative and ulcerated mass in the body of stomach. A huge gastric mass was also evident on CT scan. Histologically, the tumor was composed of diffuse undifferentiated cells with high mitotic activity and pleomorphism. Immunohistochemisty revealed intense and diffuse staining for vimentin and p53, focal staining for cytokeratin and loss of cadherin and beta-catenin in tumor cells indicative of epithelial-mesenchymal transition. Differential diagnosis was excluded by negative expression of CD56, CgA, CD3, CD20, CD10, bcl-6, S-100, CD117, CD34, desmin, SMA and HMB45. Mutations of nine genes could be found by next generation sequencing including TP53, ETV1, SOX21, GATA6, FAT1, NORCH2NL, MED12, SRC and NSD1. In addition, four genes were shown to have amplification, including SOX2, GATA2, RPTOR and CCND1, while RB1 exhibited loss of gene copy number. The patient was diagnosed as sarcomatoid carcinoma and given one cycle of chemotherapy with oxalipatin and S-1. One month later, the tumor progressed rapidly with ascitis and liver metastasis and the patient died for suspected disseminated intravascular coagulation (DIC).