Type:
Educational Exhibit
Keywords:
Head and neck, CT, Structured reporting, Neoplasia
Authors:
A. S. D. Costacurta
DOI:
10.26044/ecr2023/C-22543
Findings and procedure details
1- Describe the usual thyroidectomy neck aspect
- A) Types of surgery
- Total thyroidectomy: larger than 4 cm nodule, extrathyroidal extension, or metastatic disease.
- Hemithyroidectomy: less than 1 cm nodule, no extrathyroidal extension or metastatic disease.
- B) Surgical Bed
- Preservation of strap muscles and sternocleidomastoid muscle.
- Complete absence of glandular tissue.
- Fibrofatty connective tissue fills the surgical cavity with loss or haziness of paratracheal fat planes.
- Slight loss of volume in the central compartment.
- C) Cervical dissection
- Central dissection or removal of level VI lymph nodes is performed if a positive node is found (N1) either in the central or lateral compartments (levels II to V ).
- Lateral dissection is performed whenever a positive node (II-V) is found.
- D) Lateral compartment
- Selective lateral neck dissection for DTC metastases includes levels IIA, III, IV, and VB.
- Levels IIB and VA are spared unless imaging reveals suspicious nodes in these locations. Level I is rarely involved.
2-Discuss recurrence mimics in the surgical bed.
- Remnant of thyroid tissue, normal-appearing or diseased.
- Small indeterminate nodules.
- Small reactive lymph nodes.
- Suture granulomas and chronic granulomatous lesions.
3-Review anatomic characteristics and surgical landmarks related to recurrence patterns.
- Anatomic features may contribute to incomplete gland tissue resection.
- The surgeon may deliberately leave behind some tissue to avoid damaging important nerves.
- Anatomic variants like the Zuckerkandl tubercle (ZT) and the Pyramidal lobe, may be hard to identify during surgery.
- Advanced knowledge of the presence of ectopic tissue prevents misinterpretation later during surveillance and better planning of Radioactive Iodine Ablation (RAI).
- RAI can be administered for remnant ablation, adjuvant treatment, or treatment of known disease.
A)Thyroid gland capsule
- The thyroid gland capsule is not a well-defined anatomical fibrous capsule, but rather a pseudocapsule, derived from the midline-deep cervical fascia, and as such thyroid boundaries may be hard to delineate at surgery.
- Some “blind” spots are the posterior margin of the isthmus
, upper poles of the thyroid lobes, and tracheoesophageal groove.
- B) Thyroid anatomic variations
- The Pyramidal lobe is found in 55-65 % of patients
.
- ZT is a posterior projection of the thyroid lobe present in most patients and of variable size.
- Thyroid ectopic tissue
.
- C) Surgical landmarks for high nerve injury risk
- The upper poles of the thyroid gland are very close to the external branch of the superior laryngeal nerve (SLN). Injuries to the SLN result in poor quality voive with reduced voice pitch.
- Berry’s ligament attaches to the cricoid cartilage and extends inferomedially onto the trachea.
- It marks the laryngeal entrance point of the Recurrent Laryngeal Nerve (RLN) where most injuries occur.
4-Emphasize structural report
- A) Central compartment
- By the American Thyroid Association (ATA) consensus, the central compartment comprises the VI lymph node cervical level (visceral)
, including the surgical bed, but also the VII (superior paratracheal).
- It is bounded by the hyoid bone above and innominate artery below, laterally by the common carotid arteries, posteriorly by the deep layer of the deep cervical fascia, and anteriorly by the superficial layer.
- Residual cancer in lymph nodes is the most common cause of recurrent thyroid cancer and is frequently found in the central compartment.
Lateral compartment spread occurs later.
- Suspicious lymph node features include loss of bean shape and hilar fat, calcifications, or cystic degeneration.
Size is not a good discriminator, however central nodes >8 mm or lateral nodes >10 mm in the greater dimension in the setting of elevated serum Thyroglobulin(Tg) levels are suspicious.
- Lymph node recurrence is easily diagnosed by US-guided fine-needle aspiration biopsy and the Tg titer in the washout of the needle (FNAB-Tg), but in many cases, patients with stable lymph nodes and Tg levels are followed clinically.
- B) Lateral compartment
- Includes cervical lymph nodes levels I to V.
- C) Report
- Thyroidectomy: any remnants?
- Post-operative abnormalities?
- Suspicious nodules/masses in the surgical bed ?
- Is there an invasion of adjacent structures ?
- Presence of lymph nodes? Suspicious or not? In which compartment?