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What is A blood stained discharge from the nipple indicates - and explain in detail?
"Bloody discharge is more suggestive of cancer but is usually caused by a benign papilloma in the duct." - CSDT
"Intraductal papilloma is the most common cause of bloody nipple discharge." — Schwartz 7/e p 553

Also, remember

Nipple discharge is suggestive of cancer if it is spontaneous, unilateral, localized to a single duct, occurs in women age 40 years or more, is bloody, or is associated with a mass.
Nipple discharge is suggestive of a benign condition if it is bilateral or multiductal in origin, occurs in women age 39 years or less, or is milky or blue-green in colour.