Breast fibroadenoma !
A breast fibroadenoma is a benign lump made of gland and connective tissue; it is the most common breast lump in teenagers and young women.
Updated 2026-10-29
Structures involved
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In histology
In the clinical exam
Why it happens
What it is
Benign tumour of the breast made of glandular (epithelial) and connective (stromal) tissue. It is the most common breast lump in adolescents and young women.
Who gets it
Most frequent in women aged about 15 to 35. It often shrinks after menopause. Common worldwide, including in Colombia.
Causes
- Hormone-dependent overgrowth of the lobule's epithelium and stroma
- Oestrogen sensitivity: may grow in pregnancy or with hormone therapy
Risk factors
- Young age (adolescence to mid-thirties)
- Female sex
- Hormonal states such as pregnancy
- Immunosuppression (e.g. after transplant) in some reports
Pathophysiology
A fibroadenoma arises from the terminal duct–lobular unit as a well-circumscribed proliferation of both stroma and ducts. It is hormone sensitive, so it can enlarge in pregnancy and regress after menopause, sometimes calcifying.
Classification
- Simple fibroadenoma
- Complex fibroadenoma (with cysts, sclerosing adenosis or calcifications)
- Juvenile fibroadenoma (in adolescents, can grow fast)
- Giant fibroadenoma (larger than about 5 cm)
Symptoms and signs
- Firm, smooth, rubbery, round lump
- Very mobile under the fingers: the «breast mouse»
- Usually painless
- Usually single, sometimes multiple or bilateral
Diagnosis
- Clinical
- Smooth, mobile, painless lump in a young woman; diagnosis is confirmed by triple assessment.
- Tests
- Core needle biopsy when imaging is not typical, the lump grows, or the patient is older.
- Imaging
- Ultrasound is the first test in young women: oval, well-defined, homogeneous mass, wider than tall. Mammography in older women may show a smooth mass or popcorn calcifications.
Differential diagnosis
- Breast cyst
- Phyllodes tumour
- Breast cancer
- Fibrocystic breast changes
- Lipoma
Goal of treatment
Confirm that the lump is benign, relieve worry, and remove lumps that are large, growing, symptomatic or uncertain.
Treatment
- Follow-up
- Observation with clinical and ultrasound follow-up for small, typical, biopsy- or imaging-confirmed lesions.
- Surgical
- Surgical excision for large, growing or symptomatic lumps, uncertain histology, or patient preference.
- Procedure
- Minimally invasive options in selected centres, such as vacuum-assisted excision or cryoablation.
Complications
- Growth during pregnancy
- Distortion of breast shape with giant fibroadenomas
- Missed phyllodes tumour or cancer if not properly assessed
Prognosis
Excellent. Many stay the same size or shrink; the increase in breast cancer risk is small and mainly with complex fibroadenomas.
Test yourself
Think of the answer, then tap the question to see it.
Why is a fibroadenoma called a «breast mouse»?
Because it is very mobile and slips away under the examining fingers.
Which imaging test is used first for a breast lump in a young woman?
Ultrasound, because dense breast tissue in young women limits mammography.
What two tissue types make up a fibroadenoma?
Glandular epithelium (ducts) and fibrous stroma, both proliferating within a well-circumscribed mass.
Which tumour should be suspected if a fibroadenoma-like lump grows quickly?
Phyllodes tumour, a fibroepithelial tumour that can be benign, borderline or malignant.
Related conditions
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Breast Fibroadenoma (StatPearls (NCBI Bookshelf), 2022).
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Representative model, for educational purposes only.