IMAGING OF THE AXILLA Dr. Varda Stahl-Kent Department of Radiology and the M. Fanny Breast Institute ASSAF HAROFE MEDICAL CENTER
WHY IS IMAGING OF THE AXILLA AN IMPORTANT PART OF BREAST IMAGING? • In cases of breast cancer axillary adenopathy has high correlation with prognosis. • The number of nodes • The level of axillary involvement . • Extranodal extention
THE AXILLA -ANATOMIC BOUNDARIES • Anterior wall:pectoralis major and minor. • Posterior wall:subscapularis, latissimus dorsi and teres major muscles. • Medial wall: serratus anterior muscle. • Lateral wall: bicipital groove of humerus.
CONTENTS OF THE AXILLA • Fat, lymph nodes, arteries, veins and nerves. • Dense connective tissue that surrounds nerves and vessels. • May contain accessory breast tissue.
SURGICAL LYMPH NODE LEVELS • Level 1- low axillary group • L.N. lateral/inferior to pectoralis minor • Includes scapular, axillary vein and pectoral LOWER L.N. IN THIS GROUP ARE “SENTINEL” • Level 2 – Rotter nodes – mid-axillary group • Deep/posterior to pectoralis minor • Includes central and interpectoral and portions of subclavicular • LEVEL 1 AND 2 ARE INCLUDED IN ALND. • Level 3 – high or apical axillary group • Medial and superior to pectoralis minor
LYMPH NODES AND LYMPHATICS • 75% of drainage via lateral and medial trunks extending from areola to axilla • 25% via internal mammary chain • Anastomotic lymphatic channels may communicate with contralateral skin and breast.
IMAGING OF THE AXILLA • Should include axillary vein and artery, fat or breast tissue, lymph nodes and possible abnormality. • Accessory (ectopic) breast tissue in the axilla – common. • Benign and malignant primary tumors may occur in the axilla.
PHYSIOLOGY OF THE NORMAL LYMPH NODE • Blood enters and is drained through the hilum. • Afferent lymphatic channels enter through the capsule. • The fluid then flows to the subcapsular sinus, the cortical sinuses, and the l.n. mediastinum, to enter the medullary sinusoids. • When transcapsular arteries develop, it means that the l.n. bears metastases.
IMAGING AXILLARY L.N. WITH ULTRASOUND • Level 1, 2 and sometimes level 3 axillary nodes, and sometimes also internal mammary nodes can be seen. • Normal lymph node appearance • Usually elliptical, with long and short axes, hypoechoic cortex , hyperechoic fatty hilus. • May be longer than 2 cms. • Normal hilar vessels on Doppler exam. • Internal mammary nodes smaller than axillary, and morphology difficult to assess.
METASTASES TO AXILLARY L.N. • Malignant cells travel from breast to axilla in stepwise fashion. • Level 1 affected first, followed by 2 then 3. • Skip metastases <5%. • Likelihood of axillary involvement varies with location of breast primary. • Upper outer • Lower outer • Upper inner • Lower inner.
AXILLARY ADENOPATHY - IMAGING • Enlarged (usually >2 cm). • Absent or diminutive fatty hilum. • On mammography: Dense, rounded or irregular. • On ultrasound: Cortical thickening • Asymmetric - favors metastatic disease. • Uniformly thickened cortex - favors reactive adenopathy. • Spiculated margins suggest extranodal extension. • SHAPE IS MORE IMPORTANT THAN SIZE. • LONG TO SHORT AXIS RATIO <1.4 - PATHOLOGIC
AXILLARY ADENOPATHY – IMAGING (2) • Sensitivity for metastases 56 – 72%, specificity 70 – 90%. • Color Doppler: • Peripheral flow, transcapsular vessels favor malignancy (50% of nodes with peripheral flow – malignant, low likelihood of benign L.N)
D.D. OF AXILLARY ADENOPATHY • Metastases from breast ca. • Other metastases – melanoma, lung, ovary, thyroid • Primary breast ca. • Silicone from current or prior rupture. • HIV • Lymphoproliferative diseases • Rheumatoid arthritis / collagen vascular diseases • Previous granulomatous infection – T. B., Histoplasmosis • Gold deposits • MALIGNANT ETIOLOGIES 55% • F.N.A. PERFORMED FOR EVALUATION
WORKUP OF AXILLARY ADENOPATHY • Clinical presentation of breast ca. as palpable axillary lymph nodes is rare (0.3 – 0.8%) • If F.N.A. positive for breast ca. and primary is not demonstrated, M.R.I should be performed • Even if primary is not demonstrated, the patient is treated as having an ipsilateral breast ca. • If F.N.A does not diagnose the cause for adenopathy, follow-up in 3 months.
DIAGNOSIS AND TREATMENT OF PATIENTS WITH AXILLARY METASTASES FROM BREAST CANCER • Sentinel lymph node biopsy performed intraoperatively if lymph nodes are not proven to contain metastases (by F.N.A or trucut biopsy) • If sentinel lymph node is affected- continue to ALND. • If more than 4 nodes affected – irradiation of the axilla
INTERNAL MAMMARY LYMPH NODES • Lie between the pleura and the intercostal muscles in the first to third intercostal spaces, within 1-2 cm of the lateral sternal border. • Adjacent to the internal mammary artery and veins. • Smaller than axillary L.N., about 0.6 cm. • About 20% of patients may have metastases to internal mammary lymph nodes, but usually axillary metastases occur first.
ACCESSORY BREAST TISSUE IN AXILLA • Ectopic breast tissue – mammary tissue that persists along the embriologic “milk line.” Accessory nipples and breasts may occur. • Physiologic changes may occur during menstrual cycle, pregnancy and postpartum. • Adenomas and fibroadenomas may occur. • Carcinoma may occur (less than 1% of breast carcinomas occur in the axilla)
CALCIFICATION WITHIN AXILLARY LYMPH NODES - D.D. • Granulomatous diseases – T.B, Histoplasmosis, sarcoidosis; fat necrosis. Usually coarse. • Metastatic breast ca. – amorphous and in peripheral location. • Extramammary metastases: ovarian, thyroid. • Gold deposits – can be punctate. • Silicone deposits.