Illustration of diseases of the breast. Normal breast tissues are fat bodies (yellow) and milk- secreting glands (centre right, brown). At above right (pink) a fibro adenoma arises from gland epithelium. It is a benign (non-cancerous) tumour. To its left and dome-like in shape (silver blue) is a cyst; an abnormal lump or swelling filled with fluid or semi-solid material. Beneath it (pink) is a duct papilloma: a tumour, usually non- malignant and wart-like, that may arise from the epithelium of ducts. Below it, an infiltrating carcinoma (light blue) is a cancerous tumour in the surface layer of an organ. An abscess (dark brown) forms usually by bacterial infection.