metastatic breast signet-ring cell carcinoma from a colonic primary: review of a rare case report

Introduction: colonic signet-ring cell carcinoma is a distinctive rare subtype of adenocarcinoma with a predilection for early metastasis. among the rare extramammary metastatic adenocarcinomas to the breast, colonic signet-ring cell carcinomas constitute a small percentage. the distinction of a primary from a secondary breast signet-ring cell carcinoma is indispensable since it may result in different therapeutic approaches. here we presented a rare case of metastatic breast signet-ring cell carcinoma from a rectal origin and review its distinctive histopathologic features.case presentation: a 37-year-old woman presented with a breast mass 3 months after undergoing low anterior resection surgery to remove a rectal mass, diagnosed as signet-ring cell carcinoma. histopathologic examination of the core needle breast mass biopsy revealed tumor cells with signet-ring cell cytomorphology. the performed immunohistochemistry confirmed carcinoma of colonic origin.conclusions: colorectal signet-ring cell carcinoma is a rare and aggressive tumor. its metastatic spread is most seen in the intra-abdominal area, with seldom reported cases of breast metastasis. histologically, it can mimic a primary breast carcinoma, especially if no prior history of colonic origin exists. accurate diagnosis is important since these two entities carry different therapeutic management. proper immunophenotyping, obtaining a thorough clinical history and imaging studies facilitate a correct diagnosis.