High expression of squamous cell carcinoma antigen in poorly differentiated adenocarcinoma of the stomach: A case report

BACKGROUND: Squamous cell carcinoma antigen (SCCA) is regarded as a specific indicator of epithelial malignancies and is widely used in the diagnosis of squamous cell carcinoma (SCC). However, the expression of SCCA in gastric adenocarcinoma has not been studied in detail. CASE SUMMARY: A 52-year-old man was admitted to our hospital for a 2.5 cm × 2.5 cm ulcer at the antrum-body junction with dull pain and fullness in the upper abdomen for 2 mo. His pre-surgery serological testing results showed 0.51 ng/mL SCCA (reference interval, < 1.5 ng/mL) and 9.9 ng/mL carcinoembryonic antigen (reference range, < 4.7 ng/mL). He underwent radical distal gastrectomy and Roux-en Y anastomosis and was diagnosed with poorly differentiated mucinous adenocarcinoma (Lauren classification: Diffuse) by pathological examination of the resected lesion. Immunohistochemistry showed that SCCA was highly expressed in the cytoplasm of cancer cells. After surgery, the patient received an S-1 adjuvant chemotherapy regimen for six cycles containing tegafur, gimeracil, and oteracil potassium. He showed no sign of recurrence or metastasis within 24-mo follow-up. CONCLUSION: This is a frontal report of SCCA overexpression in poorly differentiated adenocarcinoma of the stomach.