[A Case of Invasive Ductal Carcinoma with Paget's Disease of the Breast]

Paget's disease of the breast is usually localized in the nipple epidermis and lactiferous duct located near the nipple. Here, we report a rare case of synchronous breast carcinoma with Paget's disease and invasive ductal carcinoma. A 50-year-old woman was admitted to our hospital because of abnormalities in screening mammography findings. Ultrasonography(US) findings showed a 2.4×1.3×1.6 cm sized hypoechoic lesion in a region of the left mammary gland. Computed tomography (CT)findings did not reveal distant metastasis. Magnetic resonance imaging(MRI)revealed an approximately 2.2 cm sized irregular tumor. The pretreatment diagnosis was left non-invasive ductal carcinoma(cTisN0M0, Stage 0), and surgery was performed. The tumor was found in the range of 40.2×15.0 mm, many of which were breast ductal growth. An infiltrated image was confirmed at multiple sites, but the maximum size was 2.5×1.5 mm. Pathological findings of the main lesion revealed papillotubular carcinoma. Agglomeration of heterotypic cells with abundant cytoplasm was observed in the epidermis of the papilla. The final diagnosis was invasive breast cancer(pT1aN3M0, Stage Ⅲc, Luminal HER2)coexisting with Paget's disease.