Commonest cause of blood discharge from the nipple is
High-Yield Explanation
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