Pathological Complete Response following Neoadjuvant Chemotherapy in Invasive Ductal Carcinoma with Mammary Paget's Disease: A Case Report

Mammary Paget's disease is a rare malignancy. Mastectomy or breast-conserving surgery has been considered as the standard treatment, while there have been few reports of neoadjuvant chemotherapy (NAC). A 53-year-old woman with erythema and skin ulceration of the left breast was admitted to our institution. Breast examinations revealed left invasive ductal carcinoma (cT1bN0M0, cStage I), and a punch biopsy of the left mammary erythema indicated Paget's disease (cTisN0M0, cStage0). The patient received NAC because of multiple lesions. Consequently, the breast tumor clinically disappeared, and the erythema improved. These outcomes made it easier to perform surgery (left mastectomy and sentinel node biopsy). Histopathological examination revealed no residual cancer cells in either the mammary gland or breast skin, and no metastasis was found in the sentinel lymph node. Therefore, NAC may be a useful treatment for mammary Paget's disease.