Breast Fibroadenomas

• Fibroadenomas of the breast are benign tumors:

• Composed of stromal and epithelial elements:

• That are commonly seen in young women 

• It is a common benign breast lesion:

• Results from the excess proliferation of connective tissue:

• Fibroadenomas characteristically contain both:

• Stromal and epithelial cells 

• Epidemiology: 

• They usually occur in women:

• Between the ages of 10 and 40 years

• It is the most common breast mass:

• In the adolescent and young adult population:

• Their peak incidence is between:

• 25 and 40 years:

• The incidence decreases after 40 years 

• Clinical presentation:

• The typical presentation is in a woman of reproductive age:

• With a mobile palpable breast lump

• Due to their hormonal sensitivity:

• Fibroadenomas commonly:

• Enlarge during pregnancy and involute at menopause:

• Hence, they rarely present after the age of 40 years

• The lesions are well defined and well-circumscribed clinically and the overlying skin is normal:

• The lesions are not fixed to the surrounding parenchyma and slip around under the palpating fingers:

• Hence the colloquial term a breast “mouse”

• Pathology:

• A fibroadenoma is a type of adenomatous breast lesion:

• It contains epithelium (stromal and epithelial elements):

• Has minimal malignant potential

• Multiple fibroadenomas occur in:

• 10% to 15% of patients

• Patients with multiple fibroadenomas:

• Tend to have a strong family history of these tumors

• Fibroadenomas are assumed to be:

• Aberrations of normal breast development (ANDI) or the product of hyperplastic processes:

• Rather than true neoplasms

• Fibroadenomas can be stimulated by:

• Estrogen and progesterone:

• Some fibroadenomas also have receptors and respond to:

• Growth hormone and epidermal growth factor

• When found in an adolescent girl:

• The term juvenile fibroadenoma is more appropriate 

• Location:

• Although they can be located anywhere in the breast:

• There may be a predilection for the upper outer quadrant 

• Associations:

• Cyclosporin use

• Cowden syndrome

• Multiple or complex fibroadenomas:

• May indicate a slightly increased risk for breast cancer:

• The relative risk of breast cancer in patients with such fibroadenomas: 

• Is approximately twice that of patients of similar age without fibroadenomas 

• A patient’s age:

• Determines the preferred imaging method

• In general, ultrasonography (US) is preferred:

• If a palpable mass is found

• If a patient is younger than 30 years

• If the patient is pregnant 

• Mammography and US are both useful if the patient has: 

• A palpable mass

• Is older than 30 years

• Is not pregnant

• In patients younger than 30 years: 

• The most appropriate modality is ultrasound:

• Because the patient is spared radiation exposure and because the likelihood for fibroadenoma is high

• Mammography is not indicated as the primary imaging study in women younger than 30 years:

• Unless high-risk factors are present

• Computed tomography (CT) scanning:

• Is not initially indicated for assessing a palpable lump in a woman in women younger than 30 years:

• Because of radiation exposure 

• The inability of CT to demonstrate micro-calcifications

• The lack of specificity in the findings

• Magnetic resonance imaging (MRI):

• Is not initially indicated for assessing a palpable lump in women younger than 30 year:

• Mainly because of its high cost and the high likelihood of false-positive findings

• Positron emission tomography:

• Is expensive and is not universally available

• On mammograms:

• Fibroadenomas have a spectrum of features:

• Well-circumscribed discrete oval to round mass:

• Hypodense or isodense to the breast glandular tissue:

• Mass with macro-lobulation or partially obscured margin

• Involuting fibroadenomas in older, typically postmenopausal patients may contain:

• Calcification:

• Often producing the classic:

• Coarse popcorn calcification appearance

• In some cases the whole lesion is calcified 

• Calcification may also present as crushed stone-like micro-calcification:

• Which makes differentiation from malignancy difficult 

• On ultrasound:

• Fibroadenomas appear as:

• Circumscribed, homogeneous (generally uniform hypoechogenicity), round to oval, hypoechoic masses:

• That may have gentle lobulations:

• Macro-lobulated lesion

• A smooth, thin, echogenic capsule:

• Sometimes a thin echogenic rim (pseudocapsule) may be seen sonographically 

• Variable acoustic enhancement; and homogeneity 

• Intralesional sonographically detectable calcification: 

• May be seen in approximately 10% of cases

• On MRI:

• Fibroadenomas typically appear as smooth masses:

• With high signal intensity on T2-weighted images

• Enhancement with the administration of gadolinium-based contrast

• T1:

• Typically hypointense or isointense compared with adjacent breast tissue 

• T2:

• Can be hypointense or hyperintense compared with adjacent breast tissue  

• T1 C+ (Gd):

• Can be variable:

• But a majority will show slow initial contrast enhancement:

• Followed by a persistent delayed phase:

• Type I enhancement curve:

• Non-enhancing internal septations may be seen  

• Diagnosis:

• These lesions are easily biopsied under ultrasound guidance

• When a lesion has the typical features of a fibroadenoma on ultrasound and there are no clinical red flags:

• They can be safely followed clinically 

• When lesions enlarge or have atypical imaging findings:

• Ultrasound-guided core biopsy is a minimally invasive outpatient procedure that will give a diagnosis with virtually no complications 

• There may be a maximum diameter above which a biopsy should be done if no previous imaging is available:

• The reason for intervention based on size is that a phyllodes tumor may be indistinguishable from a fibroadenoma on ultrasound:

• A maximum diameter of 2.5 cm may be a useful benchmark for biopsy if you have no previous imaging 

• Interval enlargement:

• Is an indication for biopsy 

• Symptomatic, progressively enlarging masses or atypical presentations:

• May warrant surgical excision

• If a needle biopsy shows that a mass less than 2 centimeters in size is a fibroadenoma, with no other concerning features:

• It does not have to be surgically removed

• The patient’s core biopsy pathology demonstrating a fibroadenoma is consistent with the typical imaging findings of a smooth, round, hypoechoic mass:

• As the biopsy is concordant:

• No further intervention is needed:

• Follow-up for reassurance is acceptable

• Treatment and prognosis:

• They are benign lesions with minimal or no malignant potential 

• The risk of malignant transformation is extremely low: 

• Has been reported to range around 0.0125% to 0.3%

• Indications for biopsy include: 

• Enlarging lesion 

• Atypical findings on ultrasound 

• A lesion above 2.5 cm and there are no previous studies for comparison

• Patient peace of mind:

• Some patients are simply not happy with a palpable mass in the breast without a histological diagnosis:

• This is a valid and reasonable indication for biopsy

• References:

• Tan BY, Tan PH A Diagnostic Approach to Fibroepithelial Breast Lesions. Surg Pathol Clin. 2018 Mar;11(1):17-42.

• American Society of Breast Surgeons – benign breast disease. January 8, 2018. Choosing Wisely website. http://www.choosingwisely.org/clinician-lists/asbrs-benign-breast-disease-biopsy-proven-fibroadenomas-smaller-than-2-cm/. Accessed October 17, 2019.

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