Lymph node metastases from thyroid cancer

Lymph node ultrasound plays a very important role in the initial preoperative diagnosis of thyroid cancer with lymph node metastasis and in postoperative monitoring in search of lymph node metastases or local recurrence.

Before the operation, it is important to carry out a complete assessment of the thyroid and the various lymph node territories in search of metastases.

The study of the lymph nodes is very useful especially for the lateral territories which will modify the extent of the surgical intervention.

The study of the central territories is more difficult with the thyroid in place.

Semiology

Adenomegaly is an increase in the dimensions of a lymph node without predicting its benign or malignant character.

On the other hand, an adenopathy is a pathological hypertrophy of a ganglion (inflammatory or metastatic).

Robbins Surgical Classification

Territories of thyroid drainage are territories IIa, III, IV, V and VI.

Central groups I and VI.

I territory above the hyoid bone

Side territories II III IV and V

Territory II:above the carotid bifurcation.

Territory III:above the crossing of the omohyoid muscle and the internal jugular vein.

Territory IV:above crossing of omohyoid muscle.

Territory V:posterior to the posterior edge of the SCM muscle.

The diagram is mandatory, which allows easier identification during surgery.

Criterion of malignancy of lymphadenopathy

Major signs:

The form.
Echostructure and echogenicity.
Microcalcifications.

Minor signs:

Size.
The absence of a central hilum.
Peripheral vascularization.

The major signs

1. Rounded shape

Inflammatory adenopathies are oval in shape, on the other hand metastatic adenopathies are rounded.

Non-rounded lymphadenopathy in favor of inflammatory lymphadenopathy

Round lymphadenopathy, a sign of lymph node metastasis

Round lymphadenopathy, a sign of lymph node metastasis

2. Echostructure and echogenicity

Two elements in favor of a metastasis of thyroid origin:

The presence of a liquid component.
Echogenicity close to the thyroid (thyroid like).

Nîmes University Hospital, Dr Haitham Sharara

Thyroid like and fluid component

3. Micro calcifications, a sign of lymph node metastasis

Nîmes University Hospital, Dr Haitham Sharara

Minor signs

1. Size

The diameter of the minor axis of the adenopathy is taken into account as a sign of metastasis according to the lymph node territories.

Territories close to the thyroid compartment (territories VI and IV):

The diameter of the minor axis greater than 5 mm is a minor sign in favor of lymph node metastasis.

The other territories (II III and V):

The diameter of the minor axis greater than 7 mm is a minor sign in favor of lymph node metastasis.

Territory II

The diameter of the minor axis greater than 7 mm at the level of the lymph node territory II

Territory IV

The diameter of the minor axis greater than 5 mm at the level of the lymph node territory IV

2. The absence of a central hilum

The absence of a hyperechoic central hilum is a minor sign in favor of lymph node metastasis.

At least one associated major sign is required to classify lymphadenopathy as suspicious and the absence of a hilum alone does not make lymphadenopathy a secondary location.

Hyperechoic central hilum

Inflammatory adenopathy without hilum

Metastatic adenopathy without central hilum

3. Peripheral vascularization

Peripheral vascularization is a sign of lymph node metastasis.

Inflammatory adenopathy is weakly vascularized at the level of the central hilum, on the other hand metastatic adenopathy has a strong peripheral vascularization.

Peripheral vascularization (metastasis)

Central vascularization (inflammatory)

Round lymphadenopathy without central hilum with strong peripheral and central vascularization

Indication for cervical ultrasound

Before thyroidectomy for suspected cancer, an ultrasound should be performed.

After total thyroidectomy and before IRA, a cervical ultrasound is recommended to check the lateral compartments.

6-12 months after initial treatment, a cervical ultrasound should be performed.

During follow-up and regardless of the level of risk, a cervical ultrasound is recommended in case of elevated Si Tg worsening.

After lobectomy (microcarcinoma), ultrasound monitoring is recommended for 7 years.

In low-risk patients: it is advisable to repeat the ultrasound annually (for 7 years) if the Tg is undetectable under stimulation and the ultrasound satisfactory during the first check-up at 6-12 months.

Lymph node aspiration cytology

Fine-needle aspiration under ultrasound guidance is an easy technique to perform and it confirms the metastatic nature of the lymphadenopathy.

At least two samples are necessary to measure the thyroglobulin and for a cytological analysis.

For the TG assay, the needle must be rinsed with 1 cc of NaCl.

Increase in thyroglobulin in an adenopathy compatible with a secondary localization.

The charcoal tattoo

This technique has been described to mark cervical metastases which could be difficult to detect by the surgeon intraoperatively, because of their deep location or their small size.

Main advantage = persistence for 3 months after injection.

Only complication described = Skin patch along the scar (3.6% of cases).

Injection of 0.3-0.5 ml in and around the lesion.

Injection