Intraductal papilloma

An intraductal papilloma is a small, benign, wart-like growth that develops inside one of the milk ducts (on core biopsy it is often classified as B3 — a lesion of uncertain malignant potential; see the core biopsy glossary entry) of the breast and is the most common cause of clear or blood-stained discharge from a single duct of the nipple.

Most papillomas are benign and small. They usually present as single-duct nipple discharge, often noticed only as a stain on the inside of a bra. Solitary papillomas without atypia are usually removed — often by vacuum-assisted excision (VAE) under image guidance, sometimes by a small operation called microdochectomy — to confirm the diagnosis and stop discharge.

Orientation Why you might be reading about this

You have probably been told you have an intraductal papilloma, or you are reading about possible causes of nipple discharge. Single-duct discharge can be alarming when first noticed, and the word “papilloma” sounds more concerning than it usually is. This page explains what a papilloma is, why it is sometimes recommended for removal, and what that involves.

Related terms: Breast lump · Core biopsy · Breast ultrasound · DCIS · Microdochectomy

Definition What an intraductal papilloma is

A papilloma is a small finger-like or wart-like growth that develops inside one of the milk ducts behind the nipple. It is made of normal duct lining tissue arranged on a fibrovascular stalk¹. Papillomas are usually small (a few millimetres to a centimetre), benign, and most often solitary — although a less common pattern, multiple peripheral papillomas, presents differently and is managed differently¹⁴.

The reason papillomas matter clinically is that they sit inside a duct and can cause bleeding or clear leakage from that single duct, which presents as nipple discharge. Because the discharge is from one specific duct (rather than the whole nipple), patients often notice it as a single recurring spot of fluid in the same place on the nipple, or a stain on the inside of one cup of a bra.

A small minority of papillomas have atypical features when examined by a pathologist — these are called papillomas with atypia are usually recommended for surgical excision and ongoing follow-up, rather than surveillance alone. Papillomas with atypia, are still benign, but carry a slightly raised future breast cancer risk and are usually recommended for surgical excision and ongoing follow-up.

Diagnosis How a papilloma is diagnosed

The standard pathway:

• Clinical examination of the nipple, sometimes with gentle expression to confirm which duct the discharge is coming from.
• Breast ultrasound — papillomas often appear as a small, well-defined nodule within a dilated duct, sometimes visible only when the duct contains discharge.
• Mammogram — usually performed in older patients or where the imaging picture is unclear.
• MRI — used in cases where ultrasound and mammogram do not resolve the picture, or where the discharge is bloody and persistent.
• Core biopsy — taken from any visible lesion. Biopsy of a papilloma confirms the diagnosis but, importantly, may not capture every part of the lesion; this is one reason surgical removal is usually recommended after a biopsy diagnosis.

Clinical reasoning Why surgical removal is usually recommended

For a B3 papilloma without atypia on core biopsy, current UK NHSBSP/ABS guidance recommends vacuum-assisted excision (VAE) under image guidance as first-line management. Open surgical excision — usually a microdochectomy (removal of a single duct) or total duct excision (removal of all ducts) — is offered when there is atypia on biopsy, residual disease after VAE, persistent troublesome discharge, or patient preference.

When removal is recommended, the reasons usually include:

• The needle biopsy samples only a small part of the lesion. Examining the whole specimen sometimes reveals atypical features or, occasionally, an associated DCIS that the needle biopsy did not capture². Reported upgrade rates of biopsy-proven papilloma on excision vary across published series.
• The discharge usually does not stop without removal, and recurrent or bloody discharge is socially troublesome.
• A small papilloma is a small operation — usually a microdochectomy — with a quick recovery and a high likelihood of stopping the symptom³.

For papillomas where surveillance rather than removal is being considered, the decision is individual and is reviewed at the multidisciplinary team meeting.

Number matters Solitary versus multiple papillomas

• Solitary papilloma — a single lesion, usually behind the nipple, typically presenting with single-duct discharge. The standard pattern this page describes¹.
• Multiple peripheral papillomas — a less common condition with several papillomas in the smaller ducts further out in the breast. These have a slightly higher associated risk of atypia or future cancer⁴ and are often managed with more extensive surgery and ongoing follow-up.

The two patterns look different on imaging and are managed differently; the surgical conversation is tailored to which pattern is present.

At consultation What to discuss with your surgeon

If you have been diagnosed with an intraductal papilloma, the conversation usually covers:

• Whether removal is being recommended, and why.
• The specific operation — for a solitary papilloma, this is usually a microdochectomy (single duct) or total duct excision when multiple ducts are involved.
• What the histology report from the biopsy already shows, and what additional information the excised specimen will give.
• Implications for future breastfeeding, sensation, and the cosmetic result.

Papillomas often present with nipple discharge, which is investigated in the same clinic visit.

Resources Further reading

• NHS — Nipple discharge — patient overview of common causes and when to seek help.
• Breast Cancer Now — Intraductal papilloma — patient-focused guide.
• Breastory: Non-cancerous breast conditions · Microdochectomy · Nipple discharge assessment