Intraductal papilloma

Definition

• Benign intraluminal proliferation within the breast ducts and the most common papillary lesion of the breast.

Classification

• Central papillomas lie in the large ducts behind the nipple and are more common; peripheral papillomas are smaller and often multiple.
• Depending on the extent of atypical proliferation, papillomas with atypical ductal hyperplasia (ADH) or with DCIS are distinguished from papillomas without atypia.
• In the European classification, papilloma fragments on core or vacuum-assisted biopsy are categorised as B3 lesions (uncertain malignant potential) regardless of atypia, because atypia elsewhere in the lesion cannot be excluded.

Occurrence & epidemiology

Epidemiology

• Papillomas occur mostly in perimenopausal women aged 30 to 50 years; intraductal papillomas account for approximately 20% of B3 lesions.

Clinical features

Pathological nipple discharge

• A suspicious discharge is one that is unilateral, spontaneous, bloody, and from a single duct orifice.
• On ultrasound, in cases of suspicious discharge, one looks for a dilated duct with an intraluminal mass, such as an intraductal papilloma.

• Central papillomas often cause serous or bloody nipple discharge; intraductal papilloma is the most common cause of bloody nipple discharge without a breast mass.
• Peripheral papillomas are usually asymptomatic and may be associated with microcalcifications detected on mammography.

Histology

• Histology shows arborising fibrovascular cores within a dilated duct, lined by myoepithelial cells and covered by luminal epithelial cells; this two-cell-type pattern is the hallmark of benign papillary lesions.
• Sclerosis and squamous, apocrine, mucinous or chondroid metaplasia may be present; epithelial proliferations such as ADH, atypical lobular hyperplasia or DCIS are more common in peripheral papillomas.
• The risk that DCIS or invasive carcinoma is found in subsequently obtained tissue after core biopsy of a papilloma without atypia is given as 2–3%; across studies this upgrade rate ranges from 0 to 16%.

Diagnosis

Typical imaging findings

• Ultrasound: Behind the nipple a duct is anechoically dilated. A solid hypoechoic plug sits within its lumen, broadly attached to the wall; the duct can be followed on both sides of it as a fluid-filled tube.

• On mammography papillomas, particularly small ones, are often unremarkable; larger lesions may appear as well-defined round or oval opacities with or without microcalcifications.
• On ultrasound the papilloma typically appears as a hypoechoic, well-defined lesion filling a duct or partly outlined by fluid, sometimes with a vascular stalk.
• Galactography shows filling defects in the affected duct; the diagnosis is confirmed by ultrasound-guided biopsy.

Keep learning in the app

Further reading (selection)

1. Papillary lesions of the breast (Virchows Arch 2022, PubMed Central)
2. Intraductal papilloma of the breast: low risk, but handle with care (Radiol Med 2026, PubMed Central)
3. MSD Manual Professional: Nipple Discharge
4. DocCheck Flexikon, Mastitis non-puerperalis

Cross-references