Fibroadenoma of the Breast
Definition
-
Circumscribed breast mass composed of benign stromal and epithelial cells
Alternate/Historical Names
- Adult type fibroadenoma
- Adenofibroma
Diagnostic Criteria
- Circumscribed
- Biphasic stromal and epithelial process
- Intracanalicular pattern
- Stroma compresses ducts into slit-like spaces
- Pericanalicular pattern
- Stroma surrounds round ducts
- Bland, largely fibroblastic stroma
- Myoepithelial cells and myofibroblasts not prominent
- Hypocellular to variably hypercellular
- Frequently myxoid
- May be hyalinized, especially in older patients
- May calcify
- Rare stromal changes
- Heterologous differentiation
- Smooth muscle
- Fat
- Cartilage
- Bone
- Multinucleated giant cells
- Ducts lined by epithelial and myoepithelial cells
- Fibrocystic changes may be present
- May be seen at least focally in half of cases
- Areas typical of tubular adenoma may be present
- Densely packed uniform round tubules
- Termed "adenomatous transformation"
- "Complex fibroadenoma" has been applied if any of the following are present
- Cysts >3 mm diameter
- Sclerosing adenosis
- Epithelial calcifications
- Papillary apocrine change
- Atypical ductal or lobular hyperplasia may be present
- Carcinoma, in situ or invasive, may be present
- May be lobular or ductal
- Identify using standard criteria
- Invasive carcinoma is present in adjacent breast in half of patients with in situ carcinoma in a fibroadenoma
- Mean age of cases with carcinoma is in 40's
- Necrosis may be seen rarely
- More frequent in pregnancy
- Giant fibroadenoma
- Tumors >500 g or disproportionally large compared to rest of breast
- More frequent in young and black patients
- We consider the term merely descriptive
- May be either adult or juvenile type
