Question: "Generally speaking, what would cause a bloody discharge from the nipple of only one breast in a healthy woman?"
Answer: In general, breast discharges are one-sided because they come from a single nipple duct. The vast majority of nipple discharges are benign (non-cancer) conditions.
The most common causes are known as ductal ectasia and papillomatosis.
Approximately 2-3% of all bloody nipple discharges are associated with an underlying malignancy (cancer). Frequently, a small amount of the discharge is smeared on a slide and send to the Pathology Laboratory for Cytology (microscopic analysis - very similar to a Pap Smear).
If this is benign, but the condition persists, then a biopsy may be warranted to definitively rule out the small chance of an underlying malignancy.
By Kenneth D. Hagan, M.D.
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