Atlas of breast cancer early detection

Normal axillary lymph nodes
Axillary lymph nodes in both axillae facilitate the lymphatic drainage of the breast as discussed earlier (Breast anatomy).

Level I axillary lymph nodes can be evaluated on breast ultrasound and mammography. Level II and III axillary lymph nodes are not commonly seen on ultrasound, though large reactive level II nodes may sometimes be visualized.
Ultrasound is the first-line examination for imaging the axillae.
High-frequency ultrasound examination evaluates level I nodes located in the lower part of the axilla, posterolateral to the lateral edge of the pectoralis major muscle. The evaluation of the node includes:

• size of the node;
• morphological features, including shape, contour, uniformity of the cortex, integrity of the hilum, perinodal fat plane; and
• hilar vascularity on Doppler.

A normal axillary lymph node is oval in shape with smooth, well-delineated contours, a wide central fatty hilum, and uniform peripheral cortex. The normal node measures < 10 mm in diameter and the cortex is < 3 mm thick with central hilar vascularity seen on colour Doppler ultrasound.

Abnormal axillary lymph nodes
Diseases of the lymph node begin from the periphery and an abnormal axillary lymph node will show altered morphological features such as:

• increase in size;
• loss of oval shape, maybe becoming round or irregular shape;
• cortical thickening measuring > 3 mm, with areas of focal cortical thickening > 6 mm being highly suspicious features;
• loss of fatty hilum;
• non-hilar cortical blood flow; and
• loss of contours and features of perinodal fat infiltration.

Differential diagnoses of axillary lymphadenopathy include:

• breast cancer with metastatic axillary lymph nodes ;
• infection ;
• Hodgkin lymphoma or non-Hodgkin lymphoma;
• inflammatory mastitis ;
• metastatic nodes from distant malignancy; and
• lymphoid hyperplasia.

Other causes include local infection, pet scratches, recent vaccination, injury, fungal infection, HIV, leukaemia, and melanoma.

Breast cancer with axillary metastatic node
The morphological characteristics of metastatic lymph nodes are enlarged size, round shape, absence of the fatty hilum, and concentric or focal cortical thickness greater than 3 mm.

Case 1