**4.3 Better identification of the pathological lymph nodes**

he analysis of the lymph nodes through echography and elastography requires a good deal of experience and a thorough exploration of all the zones of the breast where these nodes are to be found (axillary, para-sternal intra-mammary, intrapectoral, supra-clavicular, mediastinal, contralateral axillary and internal mammary zones)

Most lymph nodes (75%) are to be found in the axillary zone.

90% of the lymph nodes larger than 5 mm can be identified [6].

The modifications of the lymph nodes can be inflammatory, related to a systemic disease, to granulomatosis, or lastly to a metastasis of melanoma, lymphoma or breast cancer. There is a subtle classification of the metastatic criteria of the lymph nodes which are often difficult to identify Axillary metastatic nodes are to be found in half the number of breast cancers.

Lymph node elastography has a 42% sensitivity. There is a significant number of false positives. The correct positioning of the elasticity box is essential in the case of small lymph node structures.

In the case of metastatic lymph nodes, elasticity is around 20–25 kPa.

#### **Figure 7.** *SWE + 3D malignant tumour =110 kPa.*

A perfectly round lymph node without hyperechoic hilum is highly suspicious. To analyse it, it is important to make use of a Doppler examination.

A lymph node less than 2 mm large bears micro-metastases which will have but little influence on the evolution of the disease.

Lymph nodes larger than 3 mm or more bear macro-metastases which will modify significantly the general evolution of the patient.

90% of the metastatic nodes over 5 mm are thus analysed for an accurate preoperative stage, with a significant saving of time, diagnostic accuracy and cost effectiveness.

The identification of the sentinel node is important if it can be carried out.

The taking of sample cells through fine needle aspiration or core biopsy makes it possible to assert there is an invasion of the lymph nodes, thus avoiding unnecessary complete axillary lympho-node dissection.
