Paget's disease on the right breast complicated with invasive ductal carcinoma on the left side: a case report

Mammary Paget's disease (MPD) is a rare form of breast carcinoma. While the nonsynchronous coexistence of malignant tumor in one breast and Paget's disease on the other side is extremely rare. In this study, we presented a case of Paget's disease in one breast and invasive ductal carcinoma in the other breast. An 58-year-old woman presented with 5 cm x 8 cm sized, erythematous plaque on her right breast, and she'd had this lesion for 10 years. Histopathology revealed atypical neoplastic cells with cytoplasmic vacuole, nuclei varying in size and presence of mitotic figures throughout the parakeratotic. Immunohistochemical studies demonstrated that the neoplastic cells were positive for low molecular weight cytokeratin, cytokeratin 7, carcinoembryonic antigen; in contrast, they were negative for high molecular weight cytokeratin, cytokeratin 5/6, Melan-A and HMB45. However, histological examination showed invasive carcinoma on the left breast in 2009. So when breast carcinoma is been diagnosed, it is important not to ignore the possibility of the existence of a nonpalpable mass lesion on the other breast.