Left armpit subcutaneous metastasis of gastric cancer: A case report.

BACKGROUND: Gastric cancer is the third most lethal malignant tumor worldwide. Metastasis has always been a major cause of poor prognosis. Epidemiological evidence shows that the most common sites for metastasis of gastric carcinoma are the liver (48%), peritoneum (32%), lung (15%), and bone (12%); however, subcutaneous metastasis is are and occurs in approximately 0.8% of cases. We report a rare case of armpit subcutaneous metastasis of gastric cancer. The best surgical window was missed, as a result of lacking attention of the mass. CASE SUMMARY: A 69-year-old man who had previously undergone radical gastrectomy and received eight cycles of oral chemotherapy for gastric cancer showed a rapidly growing mass in his the left armpit; within just 3 mo, the mass grew to a size of 6.9 cm × 4.4 cm × 5.7 cm. Color Doppler ultrasonography and Positron emission tomography/computed tomography prompted the possibility of metastasis of the malignancy. Fine needle aspiration biopsy guided by color Doppler ultrasound showed the presence of cancer cells in the mass. Immunohistochemical examination showed CDX-2 (+), PCK (+), CK20 (+), CK7 (-), and TTF (-), which supported the metastasis of gastric cancer. Considering the risk of resection, the patient did not undergo surgical treatment. CONCLUSION: The case indicates that unidentified subcutaneous masses in patients with a history of gastric cancer should be carefully evaluated.