Thyroid pathology
Key points
Thyroid physiology
T3 and T4 - produced in thyroid follicles from iodide under the influence of Thyroid Stimulating Hormone (TSH) then attached to thyroglobulin
Ectopic thyroid tissue is poorly functioning
Will enlarge and become cystic under influence of TSH
Thyroid blood supply
Superior thyroid artery - from external carotid
Inferior thyroid artery - from thyrocervical trunk - from subclavians
Superior thyroid veins - internal jugular
Middle + inferior - brachiocephalic
Autoimmune hypothyroidism - Hashimotos
Low T3/4, raised TSH
Thyroid peroxidase and thyroglobulin antibodies may be raised
Common in Trisomy 21 + Turners
Risk for thyroid papillary cancer + thyroid lymphoma
Autoimmune hyperthyroidism - Graves disease
TSH receptor antibodies - stimulating
Most common hyperthyroidism cause in childhood
More common in adolescents
F:M 5:1
Congenital happens in 1% of babies of mothers with active Graves - causes neonatal thyrotoxicosis
Toxic multinodular goitre
Low iodine - TSH increase - thyroid cell hyperplasia - most often simple goitre
Medical treatments - carbimazole, propylthiouracil
Thyroid uptake scan
Goitre surgery for failed medical management or compression symptoms
If 'Hot nodule' found - operate
Management:
Render euthyroid + β blockade
Give lugols iodine to limit blood supply to gland + reduce risk of thyroid storm
Check PTH 4 hours post op - if normal - no need for supplements
Simple goitre
More common than TMN in children
Mostly euthyroid and surgery not indicated
Acute suppurative thyroiditis
Infective - possibly from pyriform sinus fistula
Thyroglossal cysts
Failure of thyroglossal tract to normally atrophy during week 5-10 of gestation can result in thyroglossal remnants
Lined by columnar or stratified squamous epithelium
Contains ectopic thyroid tissue in 8%
Risks inflammation and infection, in addition 1% of adult thyroid carcinomas arise in a thyroglossal cyst
Sistrunk's procedure:
Cyst invested in strap muscles
Dissect out without rupturing
Follow tract, excise middle of hyoid bone
May need to ask anaesthetist to put pressure on base of tongue to allow resection of tract at origin
10-20% recurrence - will need dissection to thyroid isthmus and larger excision of hyoid
In rare cases an incidental papillary carcinoma is found in the resection specimen
If well differentiated with no invasion or metastasis - observe
If remnants - radionuclide scan + ablation - may need thyroidectomy
References
Hirschl, Ron, et al., editors. "Thyroid Disease." Pediatric Surgery NaT, American Pediatric Surgical Association, 2020. Pediatric Surgery Library, www.pedsurglibrary.com/apsa/view/Pediatric-Surgery-NaT/829132/all/Thyroid_Disease.
Mincer DL, Jialal I. Hashimoto Thyroiditis. [Updated 2023 Jul 29]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459262/
Pokhrel B, Bhusal K. Graves Disease. [Updated 2023 Jun 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448195/
Hirschl, Ron, et al., editors. "Thyroglossal Duct Cyst." Pediatric Surgery NaT, American Pediatric Surgical Association, 2020. Pediatric Surgery Library, www.pedsurglibrary.com/apsa/view/Pediatric-Surgery-NaT/829081/all/Thyroglossal_Duct_Cyst.
Balalaa N, Megahed M, Ashari MA, Branicki F. Thyroglossal duct cyst papillary carcinoma. Case Rep Oncol. 2011 Jan 29;4(1):39-43. doi: 10.1159/000324405. PMID: 21526005; PMCID: PMC3082488.