4.8 Breast

Question 1

Breast Anatomy

Answer 1

Develops from upper third of mammary ridge between upper and lower limb buds
Clavicle to 8th rib, sternum to mid-clavicular line; Contains 20 lobes, each made up of lobules (each 500 microns, smallest structural unit of breast)

Question 2

Arterial supply of breast

Answer 2

(venous drainage follows same pattern)
UOQ - lateral thoracic artery (br of axillary),
medial / central - internal mammary (subclavian),
lateral - intercostal arteries

Lymph - mainly to axillary (75%), internal mammary (25%) and upper abdomen

Question 3

Implant rupture

Answer 3

1-2% of implants rupture
Extracapsular (implant shell and fibrous capsule) - snowstorm
Intracapsular (implant shell only) - stepladder pattern, may also diplay ‘linguini sign’
Inverted tear drop - gel bleed between inner and outer capsule

Question 4

Mammography views

Answer 4

MLO (40-60 degrees) - should have pectoralis to level of or below nipple axis, should appear convex
CC - usually allows better compression, pectoralis visible on 35%, pec-nipple distance on CC should be ≤ 1cm of MLO distance
XCCL - exaggerated craniocaudal - views axillary tail of Spence
True lateral - ML and LM for lesion localisation
Cleavage valley - between breasts
Spot compression and magnifcation - further evaluation of lesion margins, regions of tissue distortion
Tangential - for skin lesions
Rolled - if lateral roll, superior lesion moves laterally, if medial roll, superior lesion moves medially

Question 5

Lesion movement from MLO to lateral

Answer 5

Medial lesions move up, lateral lesions move down

Question 6

Mammogram tube

Answer 6

Mo anode with 17.9 and 19.5 keV peaks, Mo filter excludes >20 keV
Tube windows - Be (less filtration)
Compression - reduces blur, dose, motion, exposure time, scatter; improves resolution and separates overlapping structures

Question 7

Signs of malignancy on Mammogram

Answer 7

Margins
Spiculation (also seen in scar tissue - resolves in <1 yr if surgical, 3 yrs if radiation; desmoid tumours and fat necrosis)
Indistinct (also fat necrosis, elastosis, infection, haematomas)
Microlobulation
Obscured
Circumscribed with well-defined borders

Size
Irregularity
Density (malignant usually very dense)
Location
Multiplicity - multiple lesions likely FAs or cysts
Calcifications (reason for detection of 50% of cancers)

Question 8

BIRADs Categories

Answer 8

0 = inconclusive
1 = negative
2 = benign
3 = probably benign (95% certainty; needs biopsy / excision
6 = biopsy proven malignancy

Question 9

Malignant features of calcifications

Answer 9

Size 5 calcs/cm3
Clustered (not scattered)
Wild, fine linear branching (dot-dash)

Question 10

Breast calcifications

Answer 10

Popcorn - involuting fibroadenoma, rarely a papilloma
Fine curvilinear - walls of round mass, usually benign cyst
Dense lucent centred - fat necrosis
Linear / parallel - vascular
Calcified rods - secretory disease
Pleomorphic - <0.5 mm and with mass = intraductal cancer
Fine linear - comedonal carcinoma

Question 11

Breast MRI

Answer 11

Days 7-14 best (less physiological enhancement)
Round / oval lesions with non-enhancing septations almost always fibroadenoma
Heterogeneous and peripheral enhancement most common in malignant lesions
Cancer usually low signal on T2W

Question 12

Breast cysts

Answer 12

Usually dilatation of lobular acini, less often distended ducts; 3 mm macrocyst
Rarely (<0.2%) associated with intracystic papillary carcinoma
Mammo: Usually well defined but margins may be obscured due to pericystic inflammation, ±lucent halo (Mach effect)
Eggshell wall calcification; milk of calcium (concave crescent) on lateral, amorphous dots on CC
MR: Rarely demonstrates rim enhancement due to pericystic inflammation

Question 13

Fibrocystic breast disease

Answer 13

Can indicate increased risk of malignancy

Atypical hyperplasia x5 risk
Hyperplasia, sclerosing adenoma (x2)
No increased risk with cysts, FA, Fibrosis, Adenosis, duct ectasia, Mastitis, metaplasia

Question 14

Fibroadenoma

Answer 14

Commonest benign breast lesion, usually < 40 y/o, moblie, may have thin lucent halo
Calcification: usually popcorn (pathognomic) but can be fine and irregular (like malignancy)
US: Ovoid, hypoechoic, can have irregular internal echo pattern, can show posterior enhancement or shadowing (if fibrosis), can show lateral wall refractive shadowing
MR: T1W hypointense, T2W hyperintense, Usually enhances but non-enhancing septations are daignostic
Juvenile FA (giant FA) more cellular variant, usually at 10-20 y/o

Question 15

Phyllodes tumour (cystosarcoma phyllodes)

Answer 15

Rare, 30-50 y/o, rapidly enlarging, mobile, usually benign stromal tumour with 25% recurrence if incomplete excision
10-15% malignant with lung metastases
Malignant tumours likely if > 3 cm, contain sarcomatous elements (10% of phyllodes show haematogenous metastasis)
No spiculation and no microcalcification
US: large, well circumscribed, low amplitude internal echoes, can have posterior enhancement or attenuation
MR: rapid enhancement, indistinguishable from fibroadenoma

Question 16

Pseudoangiomatous Stromal Hyperplasia (PASH)

Answer 16

Benign proliferative lesion of mammary stroma, particularly myofibroblasts
Hypoechoic
May grow / recur following excision

Question 17

Gynaecomastia

Answer 17

True: increase in number ±dilatation of ducts, can be unilateral or bilateral
Pseudogynaecomastia: purely fat deposition
Causes
Hormones, liver failure (inadequate oestrogen degradation)
Drugs: reserpine, digoxin, spironolactone, cimetidine, thiazides, marijuana
Testicular tumours: seminoma, choriocarcinoma, embryonal cell carcinoma
Kleinfelters (increased risk breast cancer)
Lung cancer

Question 18

Hamartoma of breast

Answer 18

AKA fibroadenolipoma, proliferation of fibrous and adenomatous nodular elements, surrounded by capsule of connective tissue
3-5 cm, 75% palpable
Mammo: sharply marginated, may appear similar to lipoma, ±visible capsule
US: sharply defined, displaces surrounding structures, heterogeneous echo pattern

Question 19

Radial scar

Answer 19

Idiopathic scar-like lesion, requires biopsy
Mammo: Architectural distortion with spiculation ±microcalcifications, usually no mass, indistinguishable from cancer
US: Irregular, poorly defined, hypoechoic
MR: may appear similar to cancer

Question 20

Ductal carcinoma

Answer 20

From ductal epithelium, 90% breast cancer
DCIS if confined to duct, 30-50% proceed to invasive ductal carcinoma (breaches basement membrane of duct)
Mammo: Fine linear branching calcifications
MR: not always visible, usually pronounced segmental enhancement

Question 21

Invasive ductal carcinoma on imaging

Answer 21

Mammo: irregular mass, spiculated margin, calcification, architectural distortion, skin/nipple retraction, may be undetectable if surrounding breast same density as tumour
US: Irregular, hypoechoic, retrotumoural shadowing, vertically orientated relative to skin
MR: Irregular enhancing mass with rapid enhancement then plateau / rapid washout ± peripheral enhancement
Well differentiated form is Tubular cancer, slow growing spiculated lesion, rarely spreads to axillary LNs

Question 22

Paget’s disease of breast

Answer 22

Ductal carcinoma involving nipple, usually no evident tumour mass, good prognosis, US usually not indicated
Mammo: may be normal, occasionally microcalcification in subareolar region directed towards nipple

Question 23

Papillary carcinoma

Answer 23

Ductal epithelium proliferates into villous projections, fills lumen, slow growing
Mammo: Well circumscribed mass, lucent halo, can occur within a cyst
US: Complex solid or cystic mass, may shows as fronds projecting into a cyst

Question 24

Colloid / Mucinous carcinoma

Answer 24

Form of ductal carcinoma with mucinous differentiation
Mammo: Similar to other cancers but often lower density and well circumscribed, ±lobulation
US: Hypoechoic
MR: high signal T2W, lobulated with slow contrast enhancement

Question 25

Medullary carcinoma

Answer 25

Incidence peaks in 20’s, large, soft, movable tumour
Mammo: Well-circumscribed, smooth, ill-defined margin
US: Hypoechoic ±heterogeneous internal echoes, often posterior acoustic enhancement
MR: round, well-defined borders, diffuse enhancement

Question 26

Inflammatory carcinoma

Answer 26

Warm, erythematous, peau d’orange, painless, peaks at 30 y/o
Mammo: Skin thickening, usually no mass or calcifications, increased density on affected side due to trabecular thickening
US/MR no distinctive features

Question 27

Lobular carcinoma

Answer 27

Cells similar to those lining lobules, LCIS if confined to lobule, LCIS increases risk of invasive loblular carcinoma in both breasts
LCIS usually younger women with dense breasts, has lower risk of becoming invasive than DCIS
Usually no specific finding on mammo or US but adjacent benign tissue often has calcification

Question 28

Invasive lobular carcinoma

Answer 28

Usually large, often bilateral, insidious onset, less desmoplastic responese than ductal cancer
Mammo: early detection hard, usually asymmetric breast density / area of increasing density
US: Hypoechoic with variable posterior acoustic shadowing
MR: Similar enhancement to invasive ductal carcinoma

Question 29

Mastitis

Answer 29

Acute = puerperal, usually staphylococcus
Nonpuerperal - older patients, can form abscess
Plasma cell mastitis - rare aseptic subareolar inflammation, usually bilateral and symmetrical
Granulomatous (rare) - TB, sarcoid

Question 30

Commonly missed lesions on mammography

Answer 30

Invasive lobular carcinoma - only architectural distortion and asymmetric density visible
Invasive ductal carcinoma - commonest well-circumscribed lesion
DCIS coexisting with atypical ductal hyperplasia on bx
Palpable mass - may require spot film

Question 31

Postradiation breast

Answer 31

Usually 50 Gy total, with 60-75 Gy boosting at lumpectomy site
Diffusely dense breast most pronounced at 6 months, almost gone after 24 months
Thickening of skin and trabecula, usually resolves in months, may progress to fibrosis
Calcifications
Residual tumour (although should be surgically removed originally)
Benign dystrophic calcification (arise at 2 to 4 years, usually benign with central lucency)