Mammary Paget's disease without underlying malignancy of the breast

Mammary Paget's disease (MPD) is usually accompanied by underlying breast malignancy; however, a few cases have been reported as only skin lesions without any evidence of malignancy of the breast on imaging tests and microscopic examination of surgical specimen. Here, we describe a 47-year-old woman who visited our hospital who had an eczematous lesion on right nipple and areola for over 10 years. The lesion was diagnosed as Paget's disease by punch biopsy; however, imaging studies demonstrated no breast malignancy or lymph node metastasis. The patient underwent surgery of on the nipple and areola including underlying breast tissue. No underlying malignancy was found upon microscopic examination, except for Paget's disease. Immunohistochemical stains revealed that the tumor cells were positive for cytokeratin 7, and negativity for p63, cytokeratin 5/6, estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. We report a case of MPD without underlying malignancy. To the best of our knowledge, this is the third case reported in Korea.