Isolated invasive ductal carcinoma of the nipple-areolar complex: A rare occurrence yet to be reported in current literature.

ABSTRACT

Invasive ductal carcinoma of the nipple-areolar complex is exceedingly rare. Patients who present with bloody nipple discharge with or without the presence of Paget's disease constitute one-third of all symptomatic in situ patients. Only rarely does an invasive cancer cause nipple discharge in the absence of a clinical mass. Even more obscure is the case of the invasive cancer involving solely the nipple-areolar complex. Sir James Paget first described 'an eczematous change in the skin of the nipple preceding an underlying mammary cancer' in 1874, which is now known as Paget's disease, considered to be ductal carcinoma in situ of the nipple-areolar region. There are two competing theories as to the pathogenesis of Paget's disease of the breast-one suggests that Pagetoid cells are keratinocytes that have undergone malignant transformation. According to this theory, Paget's disease of the breast represents an in situ carcinoma of the skin-and that overlying skin changes and underlying malignancy are discontinuous. The second theory suggests that cells migrate along basement membranes and enter the epidermis and dermis of the nipple-areola complex. Pagetoid cells and underlying carcinomas demonstrate similar immunohistochemical staining patterns.