Ans. B: Obstruction of lymphatic ductsInflammatory breast cancer (IBC) is a very aggressive type of breast cancer in which the cancer cells block the lymph vessels in the skin of the breast.This type of breast cancer is called "inflammatory" because the breast often looks swollen and red, or "inflamed", sometimes overnight, and can be misdiagnosed as mastitis.Invasion of the local lymphatic ducts impairs drainage and causes edematous swelling of the breast. Because the skin of the breast is tethered by the suspensory ligament of Cooper, the accumulation of fluid may cause the skin of the breast to assume a dimpled appearance similar to an orange peel (peau d'orange).IBC is sometimes misdiagnosed as an insect bite or breast infection. In the case of IBC, a lump is usually not present as in other forms of breast cancer.