4.8 Breast Flashcards
Breast Anatomy
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)
Arterial supply of breast
(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
Implant rupture
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
Mammography views
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
Lesion movement from MLO to lateral
Medial lesions move up, lateral lesions move down
Mammogram tube
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
Signs of malignancy on Mammogram
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)
BIRADs Categories
0 = inconclusive 1 = negative 2 = benign 3 = probably benign (95% certainty; needs biopsy / excision 6 = biopsy proven malignancy
Malignant features of calcifications
Size 5 calcs/cm3
Clustered (not scattered)
Wild, fine linear branching (dot-dash)
Breast calcifications
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
Breast MRI
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
Breast cysts
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
Fibrocystic breast disease
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
Fibroadenoma
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
Phyllodes tumour (cystosarcoma phyllodes)
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
Pseudoangiomatous Stromal Hyperplasia (PASH)
Benign proliferative lesion of mammary stroma, particularly myofibroblasts
Hypoechoic
May grow / recur following excision
Gynaecomastia
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
Hamartoma of breast
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
Radial scar
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
Ductal carcinoma
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
Invasive ductal carcinoma on imaging
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
Paget’s disease of breast
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
Papillary carcinoma
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
Colloid / Mucinous carcinoma
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
