Mammary Paget disease (MPD) is a malignant intraepithelial condition of the nipple and peri-areolar skin that occurs nearly exclusively in women, usually in later adult life when breast carcinoma is more common. MPD in men is exquisitely rare.

It is widely accepted that MPD is nearly always associated with underlying breast carcinoma. Malignant cells from the underlying ductal adenocarcinoma invade the nipple unit and overlying peri-areolar skin. The malignant cells spread through the normal epidermis in "pagetoid fashion," admixed among normal keratinocytes.

Only 1%-4% of breast carcinoma presents with MPD, but nearly 100% of MPD is associated with an underlying breast carcinoma (ductal carcinoma in situ [10%] or infiltrating carcinoma [90%]).

The malignant cells of MPD express the same apomucins, and possess the chromosomal aberrations, of the underlying breast cancer. The condition is detected on biopsy using the same immunohistochemical stains employed in breast carcinoma, such as cytokeratin 7.

Treatment requires referral to a breast oncologist and oncologic surgeon for evaluation to detect and manage the underlying breast carcinoma.

Related topics: Breast cancer, Cutaneous breast cancer