Metastatic serous carcinoma presenting as inflammatory carcinoma over the breast-Report of two cases and literature review.

Non-mammary metastases involving breast are rare and most commonly involve the breast parenchyma. Infrequently, metastasis from an extramammary primary site presents as inflammatory carcinoma over the breast. Diagnosis of such lesions can be challenging, especially in patients with coexisting primary breast carcinoma. Few such cases have been described in literature; however, none of the previously reported cases had a prior history of primary breast carcinoma. We present 2 patients with history of breast carcinoma and serous carcinoma of ovarian/peritoneal origin that presented with inflammatory carcinoma over the breast. Biopsies from breast tissue showed atypical cells in the dermis forming cords and papillary structures. Histopathologic differential diagnosis included infiltrating ductal carcinoma of breast origin and metastatic serous carcinoma. Immunohistochemical studies showed that the tumor cells were positive for markers of ovarian origin such as PAX-8 and CA-125 and negative for breast markers such as GATA-3, thus supporting the diagnosis. In summary, we describe the unusual presentation of metastatic serous carcinoma as inflammatory carcinoma over breast and discuss the diagnostic challenges in patients with coexisting primary breast and ovarian malignancies. We also review the morphologic features of tumors of breast and ovarian origin and the immunohistochemical stains to differentiate these 2 entities.