Gastric Metastasis of Ectopic Breast Cancer Mimicking Axillary Metastasis of Primary Gastric Cancer

Ectopic breast tissue has the ability to undergo all the pathological changes of the normal breast, including breast cancer. Gastrointestinal metastasis of breast cancer is rarely observed and it is very difficult to differentiate gastric metastases from primary gastric cancer. We present a case of 52-year-old female, who suffered from abdominal pain. Physical examination showed a palpable mass in the left anterior axilla and computerized tomography revealed gastric wall thickening with linitis plastica. When gastroscopic biopsy showed no signs of malignancy, excisional biopsy was performed in the left axilla. Histological examination revealed invasive lobular carcinoma of the breast, consistent with ectopic breast cancer. Further gastroscopic submucosal biopsies and immunohistochemical studies revealed gastric metastases of invasive lobular carcinoma. Axillary ectopic breast tissue carcinomas can mimic axillary lymphadenopathies. Additionally, gastric metastasis of breast cancer is an uncommon but possible condition. To the best of our knowledge, this is the first report of ectopic breast cancer with gastric metastasis.