Thyroid Disorders Flashcards
Thyroid develops from
endoderm
Blood supply of thyroid
-arterial supply
-venous drainage
-nerve supply
Arterial supply
-superior thyroid artery - arise from ECA
-inferior thyroid artery - arise from thyrocervical branch
Venous drainage
-superior thyroid vein - IJV
-middle thyroid vein - IJV
-inferior thyroid vein -left brachiocephalic vein
Nerve supply
-innervated by autonomic nervous system
-sympathetic supply - superior ,middle,inferior cervical sympathetic ganglia
-parasympathetic supply - vagus nerve
How thyroid gland form ?
the gland descends from the foramen cecum via thyroglossal duct which resorb by 6 weeks of age
If fail to resorb –> thyroglossal cysts
What is the investigation you want to order in thyroid case
Thyroid Function Test
-to assess thyroid status
Ultrasound thyroid
-to assess the nodule size , nodule consistency and lymph node enlargement
FNAC
-to identify benign or malignant mass - look for capsular invasion
FNAC - cannot differentiate follicular carcinoma and follicular adenoma
Solitary Thyroid Nodule , differential diagnosis
-Dominant nodule of multinodular goitre
-thyroglossal cyst
-follicular adenoma
-thyroid cancer
Thyroglossal cyst , what is the commonest site
Near hyoid bone - located in the anterior neck
What is the treatment for thyroglossal cyst
Sistrunk operation - excision of cyst with the whole thyroglossal duct
Presentation of thyroiglossal cysts
-asymptomatic > can be symptomatic when the cyst becomes infected by oral bacteria
-painless/painful
-smooth , round , well defined mass
-move with deglutition and protrusion of tongue
Complication of thyroid disease
Local complication
-pain
-compressive sym[toms -dysphagia ,dyspnea , dysphonia
-hoarseness of voice
Systemic complication
-high output cardiac failure - ask about dyspnea ,effort tolerance
Treatment for thyroid disease
3 modalities
-anti-thyroid drugs
-surgery
-radioisotope ablation
State anti-thyroid drugs
Carbimazole - inhibit iodination and coupling of tyrosine residues on thyroglobulin
Prophythiouracil - inhibit peripheral conversion of T4 and T3
Others : reduce sympathetic stimulation - beta blocker
What is the indication of surgery (6C)
Cancer
Compressive symptoms
Cannot be treated medically
Compliance proble - in the case where the pt need long term therapy so they might struggle with this
Child bearing age -can increase the risk of preterm birth
Cosmesis - cosmetic concern
Pre-operation preparation
1)direct laryngoscopy
-to assess the vocal cord
2)make the patient euthyroid - to avoid thyroid storm (severe thyrotoxicosis) post operation
What is the mechanism of radio-iodine ablation
destroys thyroid tissue
Name the nerve that can be injured and the msucle which is supplied
Recurrent laryngeal nerves ; laryngeal muscle
Complication of the surgery
Early
-hematoma
-injury to the recurrent / superior laryngeal nerve
-tracheomalacia -floppiness of trachea
-thyrotoxic storm
Intermediate
-hypoparathyrodism leading to hypocalcemia
Late
-hypothyrodism
-permanent hypoparathyroidism
-keloid formation
-tumour recurrence
Thyroid cancer , what is the commonest and non-common one
Papillary carcinoma
Follicular carcinoma
Medullary carcinoma
Lymphoma
Anaplastic carcinoma
Papillary carcinoma of thyroid
-histopathology
-Spread
-Metastatic sites
Histopathology (PONT)
-Psamomma bodies
-Orphan Annie nuclei
-Nuclear pseudoinclusion
-Tall cell variant
Spread
-Lymphatic spread to cervical LNs
Metastatic sites
-Bone , Lung ,
Follicular carcinoma of thyroid
-histopathology
-Spread
-Metastatic sites
Histopathology
-capsular / vascular invasion by tumour cell ( follicular adenoma)
-Hurthle cell variant
Spread
-hematologic spread to lung ,bone ,brain
Metastatic sites
-lung ,bone ,brain
Medullary carcinoma of thyroid
-histopathology
-Spread
-Metastatic sites
Histopathology
-Arise from thyroid parafollicular
C cells (which produce calcitonin
→ flushing and diarrhoea
- Pathology: deposits of acellular
amyloid material – altered
calcitonin collections (shown with
Congo red stain)
- Multicentric C-cell hyperplasia (in
familial cases)
Spread
-lymphatic and hematogenous
Metastatic sites
-lung , liver ,bone ,brain
Complication of thyroglossal cyst
-thyroglossal fistula
-infection
-papillary carcinoma of thyroid
