Ductal carcinoma of the breast, infiltrating: Infiltrating ductal carcinoma is one of several recognized specific patterns of cancer of the breast. It is so named because it begins in the cells forming the ducts of the breast. It is the most common form of breast cancer, comprising 65-85% of all cases.
On a mammogram, invasive ductal carcinoma is usually visualized as a mass with fine spikes radiating from the edges (spiculation). It may also appear as a smooth edged lump in the breast.
On physical examination, this lump usually feels much harder or firmer than benign causes of lumps in the breast.
On microscopic examination, the cancerous cells invade and replace the normal breast tissue.