Benign Breast Disease

Aberrations of normal development and involution (ANDI) includes adenosis, blunt duct adenosis, sclerosing adenosis, fibrocystic change, radial scar and fibroadenoma.

Inflammation and Infection

Mastitis and Breast Abscess

Acute mastitis usually Staph Aureus or strep from nipple cracks/fissures in eary nursing. Staph usually causes abscess; strep diffuse spreading to involve whole breast.

Breast abscesses are typically subareolar in lactating women with associated pain, swelling and erythema. Increased risk in hair dressers, sheep-shearers, plucking of areolar hair, poor hygiene. Indistict margins due to inflammation. Frequent inverted nipple. Flame-like ill-defined countour, circular/oval mass. US thick pyogenic membrane. Aspirate only if >30mm or complex, may require drain.

Periductal Mastitis

(Plasma cell mastitis, recurrent subareolar abscess, squamous metaplasia of lactiferous ducts, Zuska disease). Usually smokers (in 90%) with keratinizing squamous metaplasia extending to depth causing chronic inflammation/infection with possible fistula. Many have inverted nipple. Dilated ducts filled with debri and lipid laden macrophages. Extravasation of intraductal secretions causes sterile chemical mastitis with plasma cells surrounding dilated ducts, periductal fibrosis and eventually periductal calcification. Calcifications are regular with smooth contour, highly uniform density but peripherally very dense, generally bilateral, evenly scattered. Painful poorly defined periareolar mass ± cheesy nipple secretion.

Duct Ectasia

40s-50s, usualy multiparous women. Not associated with smoking. May have thick white nipple secretion, skin retraction. Dilation of ducts, inspissation of secretions and marked chronic granulomatous inflammation, lipid-laden macrophages. Eventual fibrosis with skin and nipple retraction.

Granulomatous Mastitis

(Idiopathic/nonspecific mastitis). Granulomas secondary to systemic disease (Wegeners, sarcoidosis) or infection (mycobacterial, fungal in immunocompromised or breast prosthesis). Uncommonly granulomatous lobular mastitis in parous women confined to lobules, possibly hypersensitivity/autoimmune rection to alterations during lactation. Focal iregular density ± discharging sinus. Microabscesses. Often intermittent relapse. Tx oral steroids.

Mondor’s Disease

Superficial thrombophlebitis. 20-30yo. Lateral thoracic or superficial epigastric vv. 25% in men. Idiopathic, self-limiting, clinical diagnosis with painful or painless mass/cord, linear skin tethering/groove. From trauma, exercise, may be associated with carcinoma, rarely with DVT. Serpiginous superficial tubular structure without colour Doppler flow. Tramtrack calcifications.

Fat Necrosis

Secondary to trauma, surgery, or radiation. Can be associated with calcifications.

  • Circular/oval density – Oil cysts are generally from trauma with blood collection in an spherical/ovoid cavity, which undergoes central liquefative necrosis, walled off by collagenous tissue. Enzymes convert adipose into oil/glycerin and fatty acids. Fatty acids precipitate as calcium soaps on surface of surrounding fibrotic capsule. Up to several cm, round, lucent, thin capsule, often multiple, thin rim of eggshell calcification.
  • Sellate lesions – seldom distinct central mass (older lesions more lucent), unless necrosis from secondary healing; usually central lucent small oil cysts. Radiating fine low density spicules varying with projection. Although possible, consider malignancy (and biopsy) if there is skin thickening/retraction, architectural distortion, or if it is palpable.
  • Liponecrosis macrocystica calcificans – oil cyst with partially calcified capsule.

Fibrocystic Change

(Cystic hyperplasia, nonproliferative breast change). Common 20-40yrs, if premenopausal may persist postmenopausal. Due to hormonal imbalance (excess oestorogens cf progesterone). Rarely associated with LCIS (which is usually hidden on mammography).

  • Cysts – originate from apocrine metaplasia secreting fluid in lobules, or twisting of duct (blue-dome cysts). Microcalcifications from calcified secretory products (less likely with larger dilatation). Cysts are the most common circumscribed mass in 35-60yo (seen in 40% of women on USS), rare after menopause unless on HRT. Cysts are either simple (anechoic), complicated (echogenic fluid, dependent fluid level shifting with position) or complex (thick wall). Complex cysts are Berg I (thick walls/septa), II (intracystic mass), III (mass < cyst) or IV (mass > cyst). Simple cysts are virtually never malignant, do not require aspiration unless painful. On US round or oval, smooth-walled, anechoic, acoustic enhancement, deform with pressure. Must be examined in two projections to exclude irregularities. Thousands of psammoma bodies within ductules cause milk of calcium with “tea cup-like” calcification on MLO/lat and faint circular deposits with indistinct margins on CC. Focal or diffuse/bilateral scattered. Cyst fluid if turbid (greenish/grayish) is simple cyst, black mixture of blood and cyst fluid; but straw coloured/clear or blood (dark, melted chocolate-like with often debris) may indicate benign or malignant tumour. Following aspiration recurrence >30%, with air insufflation 5-6%. Complex cyst DDx – galactocoele, mastitis/abscess, seroma/haematoma, fat necrosis, vascular lesions, neoplasm.
  • Fibrosis – from ruptured cysts, may be circumscribed or have ill-defined borders.
  • Adenosis – increased number of acinar units per lobule without distortion, physiological during pregnancy. Occasional calcifications in the ductule lumen, can contain debris or clusters of small cysts. Blunt duct adenosis if acini are enlarged, but not distorted (cf sclerosing adenosis).

Calcification may be teacup-like on MLO/lat, circular faint opaque smudges on CC. If entire cavity solidifies there is punctate calcifications (tiny, homogeneous, evenly scattered, individually discernable, sharply outlined, spherical or pear-like densities). Involutional type calcifications are from mild cystic hyperplasia calcifying during involution, leaving fine punctate pearl-like calcifications evenly scattered in one or more lobes, uni/bi-lateral.

Lactating Adenoma

(Nodular lactational hyperplasia, lactating nodule). Pregnant or lactating women, exaggerated focal response with with physiologic adenosis and lactational changes. Often indistinguishable from FA. Mobile, but may fix to skin. Usually involutes after pregnancy/lactation, most regress or infarct. 20-30mm, may be multiple. FNA/CNB recommended.

Proliferative Breast Disease

Proliferation of ductal epithelium and/or stroma. May be isolated, associated with other proliferative or nonproliferative breast changes. May be without atypia (mildly increased risk of carcinoma) or with atypia (moderately increased risk).

Epithelial Hyperplasia

(Usual/ordinary ductal hyperplasia DH, epithiliosis, papillomatosis). Usual duct hyperplasia is increase in number of layers of cells (from normal double layer myoepithelium and epithelium above basement membrane), from proliferation or failed apoptosis. >4 layers slightly increases the risk of carcinoma 1.5-2x. Premenopausal with atypia is at greater risk of carcinoma than postmemopausal. Usually incidental finding on histology, may have nonspecific density, indeterminate calcification, focal thickening. Physiological in pregnancy. Ductal intraepithelial neoplasia (DIN) 1a is usual DH; DIN 1b/c atypical; DIN 1c/2/3 is DCIS.

Sclerosing Adenosis

Increased number of acini per TDLU with distorted and compressed acini centrally (separated by scarring), dilated peripherally, but lobular arrangement maintained. Requires continuous hormonal stimulation. Small calcifications in acini are not descernable from from each other, with multiple clusters of powderish calcifications indistinguishable from Gr1 DCIS. Strongly associated with atypical lobular hyperplasia. Without atypia there is a slightly increased risk of cancer 1.5-2x; with atypia moderate risk of 6.7x.


Small papillomas are deep within breast, usually multiple. Fibrovascular cores extend into small duct lumen, lined by normal 2-cell layer. May partially calcify – dense, uniform, often lucent areas, circular/oval with small lobulations (raspberry-like). Solitary, multiple or scattered.

Large duct intraductal/intracystic papillomas are epithelial tumours in lactiferous ducts or sinuses, <10mm, dilated duct/sinus. Spontaneous infarction from torsion on the stalk -> serous or haemorrhagic discharge. May partially calcify. 90% of discharge is caused by papillomas, 10% from breast cancer. Papillomas have slight increased risk of carcinoma 1.5-2x, surgical excision usually performed.

Multiple Papillomatosis

(Juvenile papillomatosis). Multifocal proliferation of papillary tissue with fibrovascular cores in TDLUs. 10-80mm palpable firm mass, uncommonly discharge or pain. Gross pathology well-circumscribed mass with multiple small cysts within a dense fibrous stroma (‘swiss cheese disease’). Multiple cysts with papillary proliferations. Mammography usually negative. Multiple intraductal calcifications in irregularly dilated duct system of a lobe. US heterogeneous hypoechoic multinodular areas with poorly defined margins. 58% breast carcinoma in female relatives. Mean age 20yo, almost always <30yo. 10% recurrence, 10% develop breast cancer later in life.

Complex Sclerosing Lesions

Components of sclerosing adenosis, papillomas and epithelial hyperplasia.

  • Radial scar (‘black star’, sclerosing duct hyperplasia) – Central fibroelastic nidus of entrapped glands and stroma surrounded by radiating proliferating ducts and lobules in stroma. Vary in appearance between projections. No solid/dense central mass, but translucent oval/lucent centre. Clumped thick aggregates of spicules centrally, radiolucent linear structures parallel to densities. Never skin thickening/retraction. Shadowing of nidus on USS. FNA/core biopsy/frozen section may over/under-estimate diagnosis. Tx surgical excision. Rarely palpable.
  • Sclerosing papillomas – have papillary projections.

Proliferative Breast Disease with Atypia

Moderately increased risk of cancer 4-5x, may occur in the opposite breast. >80% do not develop breast cancer. May elect to have prophylactic bilateral mastectomy, oestrogen antagonists (tamoxifen) or close surveillance.

  • Atypical ductal hyperlasia – monomorphic proliferation within ducts, but doesn’t fill ductal spaces (cf DCIS). Occasionally associated with calcification, usually adjacent to another lesion.
  • Atypical lobular hyperplasia – does not fill/distend >50% of acini in a lobule (cf LCIS), can extend to ducts. Usually incidental.

Stromal Tumours


Most common solid mass on mammography. Intralobular stromal tumour. Multiple and bilateral, likely drug-related stimulated new growth of fibrous and glandular tissue. 20-30yo, rarely appearing/growing after menopause/>40yo. May have mild increase in cancer risk, particularly if associated with fibrocystic change, proliferative disease or FHx. Almost 1/2 of women receiving cyclosporin A (for renal transpant) develop fibroadenomas. Homogeneous, spherical nodule, freely movable, hypoechoic, upper outer quadrant. May have lobulated contour, usually few large lobulations. 20% not seen on US, 10% shadow. Giant fibroadenomas are >30mm. Juvenile FAs may grow rapidly. Hormonally responsive with enlargement ± infarction/inflammation during lactation (lactating FA). Involuting FAs may have ill-defined components. May contain DCIS. Usually hypocellular, hence large core biopsy rather than FNAB. Calcification may be:

  • Popcorn-like – coarse, irregular, sharply outlined, very dense. Old fibroadenoma that has undergone myxoid degeneration (hyalinised FA).
  • Peripheral calcification – usually high uniform density, may be eggshell (rare) or flecked.
  • Crushed-stone-like – small, discernable, irregular. Mimics Gr2 DCIS.
  • Carcinoma within fibroadenoma – granular or casting malignant calcifications.

Consider biopsy ± excision if >30mm or rapid increased in size as may represent a phyllodes tumour.

Phyllodes Tumour

(Periductal stromal tumour). Intralobular stromal tumour. Perimenopausal ~50yo. Low-grade with 15-20% local recurrence if not fully excised, rarely metastasizes. Large lesions with bulbous/leaf-like protrusions into cystic spaces, sharply outlined, radiopaque. Higher cellularity and mitotic rate than fibroadenomas.

Cystosarcoma phyllodes (high grade/malignant) – 5-30% of tumours, 1/3 metastasize (most common lungs), 1/3 mortality, rarely to axillary LN. Unable to differentiate from benign phylloides or giant FA on imaging. Need >10mm margin for WLE.

Pseudoangiomatous Stromal Hyperplasia (PASH)

Interlobular stromal tumour, proliferation of fibroblasts and myofibroblasts in premenopausal or older women on HRT. Myofibroblast-lined slit-like spaces. Firm/rubbery mass. Noncalcified 50-60mm, round/oval, well-circumscribed, variable echogenicity. May have rapid growth. May have cysts.


Benign myofibroblast proliferation. The only breast tumour more common in males.


Lucent, capsule, surrounding architecture may be distorted due to mass effect or fat necrosis. Echogenic (likely due to fibrous tissue) or isoechoic, but larger and more homogeneous than normal stromal adipose. Hibernoma contains brown fat, usually in axilla/tail.


(Fibroadenolipoma). ‘Breast within a breast’. Rare, usually large, always encapsulated (thin fibrous pseudocapsule) mixed density lesion. Mixed adipose and fibroglandular tissue. ‘Cut salami’ on mammography. On US usually hyperechoic, but can be hypo-, soft and compressible.


Well-defined, hyperechoic, slow flow, compressible. Bluish overlying skin if superficial. Capillary, cavernous or venous subtypes. Kasabach-Merrit syndrome – multisystem haemangiomas with consumptive thrombocytopaenia.


Proliferation of fibroblasts and myofibroblasts. Irregular infiltrating mass involving skin and muscle. Locally aggressive, but doesn’t metastasize. Most are sporadic, occasionally associated with FAP, hereditary desmoid syndrome, Gardner syndrome.



Usually lactating or recently lactating from obstructed duct. Can be fat, mixed or water density depending on inspissated milk. May have fat-fluid level.

Breast Haematoma

Spontaneous haematomas from anticoagulants or blood dyscrasias. Secondary from trauma, aspiration or surgery. Variable ill-defined/sharp, variable echo, may contain gas or fat-fluid level. Should resolve in 6/52. If there is doubt, followup in 4-6/52.

Diabetic Mastopathy

(Diabetic fibrous breast disease DFBD). Dense parenchychmal fibrosis, usually premenopausal. Usually has other complications of diabetes. Firm, mobile, nontender mass. Acoustic shadowing.

Lymphocytic Mastopathy

(Sclerosing lymphocytic lobulitis). Single/multiple hard palpable masses, may be bilateral, may be difficult to obtain biospsy (hard texture). Collagenized stroma surrounding atrophic ducts and lobules. Most common in type 1 diabetes, autoimmune thyroid disease.

Male Gynaecomastia

Hormonal imbalance (increased oestrodial or reduced testosterone) in newborns, puberty, elderly (failing testes), Klinefelter syndrome, functioning testicular neoplasm (Leydig/Sertoli cell), hyperoestrogenism (cirrhosis reduces ability to clear oestrogen), alcohol, marijuana, heroin, anabolic steroids, psychoactive agents. Usually bilateral, assymetrical, may be unilateral. Normal male mammography has subcutaneous fat with no glandular tissue. Reversible gynaecomastia – nodular, flame shaped, florid histological pattern. Irreversible – dendritic with prominent radial extensions, histological fibrosis. US hypoechoic fibroglandular. No increased risk of carcinoma.

Cosmetic Breast Surgery

Cosmetic Oil and Gel Injections

Paraffinoma, silicone granulomas can mimic carcinoma. Free silicone injection caues multiple dense roudned opacities.

Breast Implants

Subglandular or subpectoral. Single, double or multiple lumen. Silicone, saline envelope or double-lumen implants. Silicone gel seeps/bleeds through intact shells to create a fibrous capsule and may cause capsular contractures (greater with prepectoral). Screening requires MLO, CC and ID (implant displacement) views. No proven associated with breast cancer. Complications increase with time, including:

  • Capsular contraction
  • Loss of nipple sensation
  • Puckering of skin
  • Infection
  • Rheumatologic or neurologic complications
  • Rupture from trauma or weakened outer shell with gel transported to axillary LN.
  • Herniation through rents in the capsules.
  • Rupture with free (extracapsular) or contained (intracapsular) leak best assesed with MR or less sensitive US. Linguine sign – curvilinear lines within fibrous capsule representing collapsed implant shell. Noose/inverted teardrop/keyhole sign – focus of silicone trapped outside fold of shell. Subcapsular line sign – leak through intact shell collecting on surface.

Post-mastectomy reconstruction may involve exogenous implant or autologous vascularised flap. Pedicled or free transverse rectalis abdominus myocutaneous (TRAM) flap with deep superior epigastric artery (DSEA) tunnelled to mastectomy site, or free anastomosis to axillary/internal mammary vessels. Deep inferior epigastric pedical flap involves skin and fat only. Lateral dorsi and gluteal flaps are uncommon.

Breast Reduction Surgery

Usually inferior tissue is resected with nipple/areolar complex repositioning. Tissue redistributes from upper -> lower.