Gastrointestinal metastatic signet ring cell breast cancer in young females: a case report.

Background: Signet ring cell carcinoma (SRCC) is characterized by strong invasiveness and rapid progression. It occurs mostly in young and middle-aged patients, and early patients may have no clinical symptoms. Gastric SRCC with breast cancer metastasis is relatively rare. It often presents challenges for clinicians and pathologists and may lead to an absolutely different therapeutic strategy.

Case Description: In this paper, we report on a 37-year-old woman who was admitted to the hospital with a left breast mass discovered 5 days earlier, the mass was occasionally painful, and there was no skin swelling, skin depression, or other abnormalities. The initial diagnosis considered her to have a left breast tumor. The patient was previously healthy with no family history of tumor. Considering the possibility of malignant lesions, she underwent resection of the left breast tumor and surrounding tissue. Postoperative pathological findings suggested SRCC (left breast mass). Although the patient had no history of gastrointestinal tumors, considering that SRCC can also appear in the gastrointestinal tract and other organs. We performed gastroscopy on the patient, showed an ulcerative mass in the greater curvature of the gastric body, with irregular nodular uplift of the surrounding mucosa. The excised breast lesions were analyzed by immunohistochemistry, and the pathological result showed SRCC (left breast tumor). Combined with the results of immunohistochemistry, it was consistent with gastrointestinal metastasis. Through our multi-faceted differential diagnosis, the final diagnosis of the patient was clear, which not only bought time for the patient's subsequent treatment, but also avoided misdiagnosis and blind treatment due to the particularity and rarity of the case.

Conclusions: Gastric cancer should be considered when breast tumors show SRCC without lesion. Signet ring cell gastric cancer (occult) should be excluded even if the patient has no family history of gastric cancer. It is important to distinguish metastatic cancer from primary breast cancer to avoid misdiagnosis and blind treatment due to the particularity of the case, at which point an early recognition can be made and an optimal treatment plan can be chosen.