Commonest cause of blood discharge from the nipple is
Duct papilloma is the Commonest cause of blood discharge from the nipple Duct papilloma are epithelium lined true polyps of breast lactiferous ducts it is usually single,from a single lactiferous duct it blocks the duct causing ductal dialatation ref ;(page no;528) 5th edition of SRB&;S Manual of SURGERY
Duct carcinoma
Duct papilloma
Chronic cystic mastitis
Cystosarcoma phyllodes
Endocrinology and breast