Inflammatory breast cancer is a pattern of invasive breast cancer in which the neoplastic cells infiltrate widely through the breast tissue. The cancer involves dermal lymphatics and therefore has a high incidence of systemic metastasis and a poor prognosis. If the lymphatics become blocked, then the area of skin may develop lymphedema and "peau d'orange" or orange peel appearance. The overlying skin in inflammatory breast cancer is usually swollen, red, and tender. Acute inflammation is a rare finding in breast cancer and may be associated with secondary infection or abscess. Chronic inflammation in breast cancer is a non-specific finding. In medullary breast cancer, a type of invasive ductal carcinoma, there are a large number of lymphocytes around the tumor and a desmoplastic reaction is often absent in the surrounding tissue. This type of cancer carries a somewhat better prognosis. Epidermal invasion by cancer cells is a poor prognostic indicator. Intraepidermal malignant cells are called Paget cells. Paget's disease of the nipple is a type of ductal carcinoma that arises in large ducts and spreads intraepidermal to the skin of the nipple and areola. There is usually an underlying ductal carcinoma.