Bilateral paget disease of the nipple associated with lobular carcinoma in situ.

We report synchronous bilateral Paget disease derived from lobular carcinoma in situ in a 53-year-old woman who underwent bilateral mastectomy. The epidermis of both nipples contained small cells with a moderate amount of pale-staining cytoplasm. The nuclei had fine chromatin and identifiable nucleoli. The cells were strongly immunoreactive with cytokeratin 7 and displayed nuclear estrogen receptor reactivity. The underlying mammary gland showed involvement by lobular carcinoma in situ with pagetoid spread into lactiferous ducts, which was confirmed by lack of immunoreactivity for E-cadherin.