• Fibroadenomas:
    • Are benign tumors composed of stromal and epithelial elements
    • That are commonly seen in young women
    • 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 o In patients younger than 30 years: 
          • The most appropriate modality is US:
            • Because the patient is spared radiation exposure and because the likelihood for fibroadenoma is not that 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 finding
      • Positron emission tomography: 
        • Is expensive and is not universally available
  • On mammograms:
    • Fibroadenomas typically appear as:
      • Circumscribed oval or round masses:
        • Which occasionally have coarse calcifications
  • On ultrasonograms:
    • Fibroadenomas appear as circumscribed, homogeneous, oval, hypoechoic masses:
      • That may have gentle lobulations 
      • A smooth, thin, echogenic capsule 
      • Variable acoustic enhancement; and homogeneity
  • On MRI:
    • Fibroadenomas typically appear as smooth masses with high signal intensity on T2-weighted images and enhancement with the administration of gadolinium-based contrast agent
  • Fibroadenoma:
    • 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
      • Fibroadenomas commonly enlarge during pregnancy and involute at menopause: • Hence, they rarely present after the age of 40 years o The lesions are well defined and well-circumscribed clinically and the overlying skin is normal o The lesions are not fixed to the surrounding parenchyma and slip around under the palpating fingers:  Hence the colloquial term a breast “mouse”. • Pathology: o A fibroadenoma is a type of adenomatous breast lesion:  It contains epithelium  Has minimal malignant potential o Multiple fibroadenomas occur in:  10% to 15% of patients: • Patients with multiple fibroadenomas: o Tend to have a strong family history of these tumors o They are assumed to be:  Aberrations of normal breast development (ANDI) or the product of hyperplastic processes: • Rather than true neoplasms o Fibroadenomas can be stimulated by estrogen and progesterone o Some fibroadenomas also have receptors and respond to:  Growth hormone and epidermal growth factor o When found in an adolescent girl:  The term juvenile fibroadenoma is more appropriate • Location: o Although they can be located anywhere in the breast:  There may be a predilection for the upper outer quadrant • Associations: o Cyclosporin use o Cowden syndrome • Radiographic features: o Mammography:  Fibroadenomas have a spectrum of features: • Well-circumscribed discrete oval 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: o 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 • Breast ultrasound: o Typically seen as a well-circumscribed, round to ovoid, or macro-lobulated mass with generally uniform hypoechogenicity o Intralesional sonographically detectable calcification:  May be seen in approximately 10% of cases o Sometimes a thin echogenic rim (pseudo capsule) may be seen sonographically • Breast MRI: o T1: typically hypo intense or isointense compared with adjacent breast tissue o T2: can be hypo- or hyper intense o 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: o These lesions are easily biopsied under ultrasound guidance o 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 o 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 o 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 o Interval enlargement is an indication for biopsy • Treatment and prognosis: o They are benign lesions with minimal or no malignant potential o The risk of malignant transformation is extremely low:  Has been reported to range around 0.0125% to 0.3%. o 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: o This is a valid and reasonable indication for biopsy

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