4.8 Breast Flashcards
Breast Anatomy - blood and LN drainage
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) Terminal duct (origin of breast cancers) lobular unit - branches of major duct and its lobule TDLU epithelium has 2 layers - luminal true epithelial and deep myoepithelial Arterial supply (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 - site, risk, imaging
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
Should have fat visible behind glandular tissue on all 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 less than or equal to 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 magnification - 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
Mammography tube, purpose of compression
Lesion movement from MLO to lateral - medial lesions move up, lateral lesions move down
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
Standard mammographic views for implants
CC, MLO, Implant displaced CC and MLO (Ecklund)
Evaluation of mammogram
Quality and penetration Skin, nipple and trabecular changes Presence of masses and calcifications Axillary nodes Asymmetry Architectural distortion Signs of malignancy = spiculated / ill-defined mass, clustered microcalcifications, enlarged LNs
Signs of malignancy on Mammogram
Margins: Spiculation (also seen in scar tissue - resolves in less than 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 (less than 2% risk malignacy) - 6 month follow-up 4 = suspicious; consider biopsy 5 = cancer >95% certainty; needs biopsy / excision 6 = biopsy proven malignancy
Malignant features of calcifications
Size less than 1 mm
Less than 5 calcs/cm3
Clustered (not scattered)
Wild, fine linear branching (dot-dash)
Breast calcifications types
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 - less than 0.5 mm and with mass = intraductal cancer
Fine linear - comedonal carcinoma
Breast MRI - timing, malignancy
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
Enhancing breast lesions on MRI
Cancer Fibroadenomas Fibrocystic change (including sclerosing adenosis) Fat necrosis Radial scars Mastitis Atypical hyperplasia Lobular neoplasia Normal breast tissue
Breast cysts - definition, association, imaging
Usually dilatation of lobular acini, less often distended ducts; less than 3 mm microcyst, >3 mm macrocyst
Rarely (less than 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 - risk
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 - CFs, imaging
Commonest benign breast lesion, usually less than 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 - CFs, imaging, metastases location
AKA 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
