Download Congenital anomalies of the face

Thyroid gland
Embryology:
Thyroid gland develops from the thyroglossal duct which passes from the foramen
caecum to the isthmus of thyroid. Parafollicular cells (C-cells) develops from the
neural crest.
Surgical anatomy:
The gland is formed from two lateral lobes, isthmus, and pyramidal lobe.
Weight is about 20-25 gm.
The lobe if formed from multiple follicles.
Arterial supply: superior and inferior thyroid arteries and rarely thyroid imma artery,
and anastomotic branches from trachea and oesophagus
Venous drainage: superior middle and inferior thyroid veins.
Lymphatic drainage: Pretracheal, paratracheal and nodes along thyroid veins to the
deep cervical group.
Anomalies of the thyroglossal tract:
It is residual thyroid tissues at the course of the thyroglossal duct  ectopic gland.
Lingual thyroid:
It is arrested gland at the back of tongue at the foramen caecum interfering
with speech, respiration and swallowing.
Median ectopic thyroid:
At any site of the course of thyroglossal duct.
Lateral aberrant thyroid:
The thyroid tissue never separate laterally. It is metastases in a lymph node
from thyroid malignancy.
Thyroglossal cyst:
It is at any site of course of the duct due to dilatation and obstruction at any site
of the duct.
Sites:
1. Beneath foramen caecum.
2. floor of the mouth.
3. suprahyoid.
4. subhyoid.
5. On thyroid cartilage.
6. At level of the cricoid cartilage.
Thyroglossal fistula:
Never congenital it is due to infection or incomplete removal of a thyroglossal
cyst. It presents by a midline fistula discharging purulent discharge. It is treated
by Sis-trunk operation.
Physiology of the thyroid gland:
Pituitary thyroid axis:
Thyroid stimulating hormone (TSH) from the anterior pituitary stimulates the
thyroid gland to secrete T3 and T4 which have a negative feedback on TSH.
Thyrotropin releasing hormone from the hypothalamus stimulates the release
of TSH.
Thyroid Stimulating Antibodies:
IgG immunoglobulin bind with TSH receptors at the thyroid gland and activate
its function. it is responsible for thyrotoxicosis.
Thyroid enlargement:
Gutter = Throat = Goiter
Simple goiter:
diffuse:
physiological
Colloidal
Nodular:
Solitary thyroid module
Multinodular goiter
Toxic goiter:
diffuse:
Graves disease
Nodular:
Solitary toxic module
Multinodular goiter (Plummer disease)
Neoplastic:
Benign
Malignant
Inflammatory:
Autoimmune disease.
Composition of follicles:
Cubical cells around central colloid.
Hyperplastic follicles: columnar cells around small area of colloid.
Hypoplastic flat cell around large area of colloid.
Then areas of active and inactive follicles leading to heamorrhage and necrosis
leading to fibrosis ending in a nodule which is inactive surrounded by active
follicles.
Simple goiter:
Complications:
 heamorrhage
 Tracheal obstruction.
 Secondary thyrotoxicosis
 Carcinoma.
Diagnosis:
 Clinically
 Investigation.
Retrosternal goiter:
Occurs commonly in males due to strong muscles where the thyroid passes
downward behind the sternum leading to airway and vascular obstruction.
Thyroid cyst:
Occurs as a complication in thyroid enlargement. Heamorrhage inside the cyst
leads to severe pain due to muscle spasm. It is treated by rapid aspiration by a
wide bore canula followed by thyrodectomy.
Thyrotoxicosis
(Hyperthyroidism)
types:
Diffuse toxic goiter (Graves' disease)
Toxic nodular goiter
Toxic nodule
Rare causes.
1- Graves' disease:
Diffuse, highly vascular occurs in young age.
Female to male ratio 8:1
Associated with eye signs.
Aetiology: high level of thyroid stimulating antibodies leading to diffuse
hypertrophy and hyperplasia of the gland.
2- Toxic nodular goiter:
It is toxic transformation in simple nodular goiter. It occurs in older age
females. Rarely associated with eye signs.
Aetiology autonomous activity due to long standing goiter. The internodular
thyroid tissue is over active.
3- Toxic nodule:
It occurs at any age rarely associated with eye signs.
Aetiology autonomous activity in the nodule the rest of the gland is
suppressed.
Histology:
Tall columnar cells and empty acini.
Clinical picture:
Symptoms: tiredness, fatigability, emotional disturbance, hyperexitability,
heat intolerance, weight loss and increased appetite, tremors, anxiety and
palpitation.
Signs: Tachycardia, sweating, moist hand, exophthalmus, lid lag and thyroid
swelling.
Complications:
Eye problems
Cardiac problems: Arrhythmia, extrasystole
Myopathy: weakness of proximal limb muscles.
Investigations:
T3, T4, TSH and thyroidscan.
Treatment:
Medical:
Antithyroid drugs: carbimazole
 adrenergic blockers : Propranolol.
Iodides : lugol's iodine.
Durations: 18-24 months
Advantages : no operation
Disadvantages : long duration - not sure of remission.
Surgical:
Operation subtotal thryoidectomy
Preoperative preparations: antithyroid drugs until the patient is euthryoid
then Lugol's iodine for 10 days before the operation.
Extent of resection depends on the size of the gland. Sometimes total
thyroidectomy and thyroid replacement is needed.
Radioactive iodine:
It destroys the thyroid cells = thyrodectomy
Advantages : No operation.
Disadvantages : difficult - carcinogenic.
Indications: old high risk patient.
Neoplasm of the thyroid
Benign:
Follicular adenoma
Rare papillary adenoma.
Malignant:
Follicular carcinoma: occurs as a malignant transformation in a long standing
simple nodular goiter.
papillary carcinoma: occurs in young age, it is of good prognosis.
Anaplastic carcinoma: occurs in old age, it is of bad prognosis.
Medullary carcinoma: arises from C-cells, it is a functioning tumour
secreting serotonin.
Lymphoma.
Treatment:
Surgical: total thyroidectomy
Thyroxin: postoperative as a replacement and to depress TSH to prevent
recurrence.
Radioactive iodine: to control metastases.