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Intraductal papilloma is a benign epithelial tumor arising within the mammary ducts, composed of fibrovascular cores lined by both luminal epithelial and myoepithelial cells. It is one of the most common causes of pathologic nipple discharge, particularly bloody or serous.
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Classification
| Type |
Description |
| Central (solitary) |
Usually subareolar, single lesion, affects perimenopausal women |
| Peripheral (multiple) |
Often bilateral, located deeper in the breast, seen in younger women; higher risk of atypia or malignancy |
Pathology
- Fibrovascular stalks protrude into a dilated ductal lumen
- May exhibit:
- Epithelial hyperplasia
- Atypical ductal hyperplasia (ADH)
- Rarely, harbor ductal carcinoma in situ (DCIS) or invasive carcinoma
- Myoepithelial cell layer is intact in benign lesions (key feature)
Malignant potential:
- Solitary papilloma without atypia: low risk
- Papilloma with atypia (e.g., ADH): increased relative risk of future breast cancer (RR ~4–5)
- Multiple papillomas: higher association with DCIS or invasive ductal carcinoma
Clinical Features
- Nipple discharge (most common presentation)
- Spontaneous, unilateral, serous or bloody
- May present as a palpable subareolar mass or be asymptomatic
- Peripheral papillomas often non-palpable
Radiology