Mammary Paget Disease : Pathogenesis
Pathogenesis of Paget disease (PD) of the Breast: PD arises by intraepidermal migration of ductal carcinoma cells through the lactiferous ducts to the surface epithelium of the nipple and areola. It is most commonly associated with invasive ductal carcinoma of breast or DCIS, but rare cases arise in association with invasive papillary carcinoma and mucinous breast carcinoma. There are rare cases of PD in which no underlying breast carcinoma is identified by palpation and imaging studies. An alternative origin from the epidermal Toker cells (TCs) has been proposed for such cases. Both TCs and PD have same mucin phenotypes (MUC1, MUC2, & MUC5AC). It has also been proposed that PD may arise by in-situ transformation of the cells of the terminal lactiferous duct at its junction with the epidermis. This could account for the cases of PD that are not associated with carcinoma or are anatomically remote from the carcinoma. This clinical photograph of PD shows a hyperemic erosive lesion extending from 7 o'clock to 9 o'clock. There was no associated palpable breast mass.