Benign fibroepithelial breast tumor — most common breast mass in women under 30.
Also known as: fibroadenoma, breast fibroadenoma, giant fibroadenoma
Overview
Benign biphasic (epithelial and stromal) tumor of the breast arising from the terminal ductal lobular unit. Most common breast tumor in adolescents and women under 30.
Epidemiology
Peak incidence ages 15-35. Found in ~10% of women at some point. Often multiple and bilateral. Spontaneous regression occurs in some, especially after menopause.
Try a board-style Fibroadenoma question
Real questions from the FirstPassPA bank, with the full explanation. Pick an answer — no signup, no email.
Question 1ReproductiveMedium
A 23-year-old woman presents with a painless lump in the upper outer right breast that she noticed 2 months ago and that has not changed in size. She takes no medications and has no family history of breast or ovarian cancer. On exam there is a 1.5-cm firm, rubbery, well-circumscribed, highly mobile mass with no overlying skin changes and no axillary lymphadenopathy. Ultrasound shows an oval, well-circumscribed, hypoechoic mass with parallel orientation, and core needle biopsy confirms a simple fibroadenoma. Which of the following is the most appropriate initial management?
ASurgical excision of the lesion
BClinical and imaging follow-up
CUltrasound-guided cryoablation
DVacuum-assisted core re-biopsy
Reveal answer & full explanation
Correct answer: B — Clinical and imaging follow-up
ASurgical excision of the lesion
BClinical and imaging follow-up✓
CUltrasound-guided cryoablation
DVacuum-assisted core re-biopsy
Why Clinical and imaging follow-up is correct
A small, biopsy-proven simple fibroadenoma with concordant clinical and imaging features carries no increased breast cancer risk and may regress spontaneously.
First-line management is observation with clinical exam and imaging follow-up (typically at 6 and 12 months); no intervention is required for an asymptomatic lesion under 2-3 cm.
Why the others are wrong
Surgical excision of the lesion — reserved for symptomatic, rapidly growing, or large (>3-4 cm) lesions, atypia, imaging-pathology discordance, or suspected phyllodes tumor; this concordant, stable, small mass does not meet excision criteria.
Ultrasound-guided cryoablation — an FDA-approved minimally invasive option for selected small fibroadenomas, but it is reserved for patients who desire removal rather than being first-line; observation is preferred when the diagnosis is secure.
Vacuum-assisted core re-biopsy — repeat sampling is indicated for imaging-pathology discordance or an inadequate specimen; her benign core result matches the BI-RADS 3 sonographic features, so re-biopsy would add nothing.
🔒 Free preview limit reached
Keep reading — start your free trial
You've read your 2 free diagnosis previews. Create your free account to unlock the full Fibroadenoma outline — plus all 514 diagnoses, 6,500+ board-style questions, flashcards, and an AI tutor. Your 7-day free trial includes everything, and there's no credit card required.
Adolescence and young adulthood (estrogen exposure)
Cyclosporine use (transplant patients)
Pregnancy and lactation (growth)
Black women (higher incidence)
Pathophysiology
Hormonally responsive benign neoplasm of stromal and epithelial elements. Growth driven by estrogen, often enlarging during pregnancy or with hormonal contraception. Histologic variants include simple (no proliferation, no increased cancer risk) and complex fibroadenomas (epithelial proliferation, cysts, sclerosing adenosis, calcifications — modest increased cancer risk).
Clinical presentation
Symptoms
Painless, slow-growing, smooth mass
Mobile under the skin ('breast mouse')
Usually solitary but can be multiple/bilateral
May grow during pregnancy or with hormonal therapy
Signs / physical exam
Firm, rubbery, well-circumscribed, highly mobile mass
Usually 1-3 cm; 'giant fibroadenoma' >5 cm
No skin or nipple changes; no lymphadenopathy
Classic findings
Young woman with a firm, rubbery, mobile, painless breast mass — well-circumscribed on ultrasound.
Differential diagnosis
Phyllodes tumor — Rapidly enlarging, may be very large; histology distinguishes — biphasic with cellular stroma
Breast cyst — Anechoic on ultrasound, fluctuant; aspirate
Breast cancer — Older patients, irregular and fixed; abnormal mammography; biopsy
Tubular adenoma — Similar to fibroadenoma but less stroma; benign
Hamartoma — Fatty and fibroglandular tissue; distinctive 'breast within a breast' appearance
Diagnostic workup
Imaging
Ultrasound — first-line for women <30; well-circumscribed, hypoechoic, oval mass with parallel orientation
Mammography for women ≥30 — round/oval mass with smooth margins; coarse 'popcorn' calcifications in involuting older lesions
Core needle biopsy — definitive diagnosis; recommended for masses >2 cm, growing lesions, atypical imaging, or older patients
Fine-needle aspiration may be used but core biopsy preferred to distinguish from phyllodes
Diagnostic algorithm
Feature
Fibroadenoma
Phyllodes Tumor
Breast Cancer
Typical age
15-35
35-55
>40
Growth
Slow
Often rapid
Variable
Size
1-3 cm
Often >4 cm, can be huge
Variable
Texture
Firm, rubbery, mobile
Firm, mobile, may be lobulated
Hard, fixed, irregular
Skin/nipple changes
None
Skin stretching with size
Dimpling, retraction
Imaging
Smooth oval mass
Lobulated mass, can be large
Spiculated, calcifications
Treatment
Observation or excision
Wide local excision (>1 cm margins)
Multimodality
Differentiating fibroadenoma from phyllodes tumor and cancer.
Treatment
First-line
Observation — for biopsy-proven simple fibroadenomas; clinical exam and imaging follow-up at 6 and 12 months
Reassurance
No restrictions on activities, contraception, or pregnancy
Surgical excision
Patient preference
Symptomatic, rapidly growing, or >3-4 cm
Atypia on biopsy or imaging-pathology discordance
Suspicion of phyllodes tumor
Cosmetic concern
Minimally invasive options
Cryoablation — FDA approved for small fibroadenomas (<4 cm)
Vacuum-assisted excision for selected lesions
Radiofrequency ablation (investigational)
Complications
Continued growth, especially during pregnancy
Complex fibroadenoma → modest increased breast cancer risk (~1.5-2x)
Phyllodes tumor misdiagnosed as fibroadenoma — wider excision required
Cosmetic deformity from large or multiple lesions
Anxiety from new breast mass
PANCE pearls
Simple fibroadenomas confer no increased breast cancer risk; complex fibroadenomas slightly increase risk.
Rapidly enlarging breast mass in a young woman — consider giant fibroadenoma or phyllodes tumor; excise.
Phyllodes tumor is distinguished from fibroadenoma by histology (cellular stroma); core needle biopsy may not reliably differentiate — excision often needed.
Coarse 'popcorn' calcifications in an older woman's mammogram suggest involuting fibroadenoma.
Adolescents with classic clinical and ultrasound features may be observed without biopsy with appropriate follow-up.
References
ACOG CO 821 — ACOG Committee Opinion 821: Benign Breast Conditions and Management
ASBrS 2019 — ASBrS Consensus Guideline on Concordance Assessment of Image-Guided Breast Biopsies and Management of Borderline or High-Risk Lesions
Practice Reproductive questions on FirstPassPA
Turn this outline into retention. 6,500+ board-style questions with an AI tutor that explains every answer — free to start, no card required.
Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA or PAEA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants; End of Rotation™ is a program of the Physician Assistant Education Association.