Ultrasound of the Neck

Ultrasound (5-12 MHz) supplemented with fine needle aspiration of the neck lymph nodes is the most reliable technique to detect occult cervical lymph node metastases

  • The specificity approaches 100% in the untreated neck
  • The sensitivity for N0 disease is between 20-50% depending on the group of patients studied and the sonographer
  • For deep structures, a 5 MHz probe can be optimal

In clinical N + neck it is in general not necessary to aspirate other lymph nodes on the tumor positive side, except in exceptional cases when explicitly asked to assess metastases in other levels (eg. To determine extent of surgery or radiotherapy)

In a clinical N0 neck ultrasound-guided aspiration is indicated when there is a significant risk of occult metastases and when this has implications for treatment:

  • > T1 laryngeal
  • all other HNSCC > CIS
    • also attention to contralateral side for tumors that grow near / over the median line
  • skin tumors (SCC), greater than 2 cm
  • melanomas > 1 mm
  • malignant tumors salivary glands (ipsilateral)

Lymph nodes are aspirated:

  • Ultrasound suspicious nodes (spheric, hypo-echogenic, focal cortical thickening, etc.) always fine needle aspiration (basically whatever minimal axial diameter)
  • Ultrasound unsuspected lymph nodes:
    • Level I: if minimum axial diameter ≥ 5 mm
    • Level II: if minimum axial diameter ≥ 7 mm
    • Level III t / m VI: if minimum axial diameter ≥ 5 mm
  • When there is an obvious suspicious lymph node present, only this one is punctured (8-11 mm, etc.). When there are only unsuspicious nodes present (4-6 mm), multiple nodes are punctured up to 2-3  per side in the first echelons.

Guideline for the lymph node selection

  • In oral cavity and nose (sinus) tumors levels I-II
  • In oropharynx- hypo pharynx and larynx cancer levels II and III
  • In hypopharynx- and larynx tumors moreover paratracheal regions (level VI)
  • Skin cancer often spread to more superficial nodes (also occipital and level V) and parotid nodes
  • Level IV and V are rarely affected (unlike in thyroid or skin tumors)
  • After radiotherapy and previous neck surgery aberrant patterns of metastases occur
  • Midline tumors, but also unilateral tumors can present with contralateral metastases, especially when ipsilateral metastases are present
  • CT, PET-CT and MRI may point to borderline lymph nodes that can be aspirated using US-FNAC.

Indications for US-FNAC follow-up

  • When a N0 neck is not treated
    • After transoral excision of T1-2 oral cavity, oropharynx or larynx carcinomas (except T1 glottic): at 3 months interval for one year.
    • Occasionally the untreated contralateral neck with a midline tumor involving a unilateral treatment (not routinely)
  • If a N+ neck has been treated with radiotherapy/chemoradiation, there is a good indication of US-FNAC follow-up at 3 months (specificity << 100%)
  • In thyroid cancer: for follow-up of high risk patients at 6 months post treatment (see guidelines in oncoline)
  • In case of palpable lesions, cytology without ultrasound can be tried first, and ultrasound guidance is indicated in case of non-diagnostic cytology.

When the neck has been treated surgically or by neck dissection with radiotherapy, routine radiological follow-up is not indicated because the chance of a neck recurrence is limited (<10%) and rarely curative options exist when there is a recurrence.

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