Anatomy and brief description on benign thyroid swellings

1. BENIGNTHYROID
SWELLINGS
ROSSHINI JAGATHESWARAN

2. CONTENTS
■ Surgical anatomy
■ Physiology
■ Tests of thyroid function
■ Thyroid enlargement
- Simple goiter
- Clinically discrete swellings
■ Hyperthyroidism
-Thyrotoxicosis
■ Thyroiditis

3. Thyroid gland
ANATOMY

4. ■ Location:
Lower part of front and sides of neck
opposite C5,6 & 7.
■ Parts:
 Two lateral lobes, right and left (extend
from middle of thyroid cartilage to 4th
tracheal ring)
 Joined by isthmus (isthmus extends from
2-3 tracheal rings).
 Sometimes a third pyramidal lobe may
project upward from the isthmus.
■ Coverings (capsules):
 Inner true capsule, condensation of
connective tissue.
 Outer false capsule, derived from
pretracheal fascia of deep cervical
 False capsule is thickened to form
ligament of Berry (connects medial
surface of lateral lobe to cricoid cartilage.)

6. Thyroid gland (relations)
1. Lobes- are conical having apex,base and 3 surfaces -
lateral,medial and posterolateral.
 Lateral surface: Sternothyroid, sternohyoid, superior belly
omohyoid and sternocleidomastoid.
 Medial surface:
- 2 tubes :Trachea, oesophagus.
- 2 muscles : inferior constrictor, cricothyroid
- 2 nerves : external laryngeal and recurrent laryngeal.
 Postero lateral surface: Carotid sheath and common carotid
artery.
2. Isthmus – 2 surfaces:
 Anterior surface related to sternohyoid and sternothyroid
muscles.
 Posterior surface is related to 2nd and 3rd tracheal rings.

8. Arterial Supply:
■ Superior and inferior
thyroid arteries.
■ Thyroidea ima (when
present) originates
from aortic arch or
brachiocephalic trunk,
enters the thyroid at
inferior border of
isthmus.

9. ■ Superior thyroid artery is closely
related to external laryngeal nerve.
■ Inferior thyroid artery is closely
related to recurrent laryngeal
nerve.
■ Surgical importance: Careful
ligation in thyroid surgery.

10. Venous drainage
3 pairs of veins:
1.Superior thyroid vein – ascend
along superior thyroid artery
and drains into the internal
jugular vein.
2.Middlle thyroid vein – directly
lateral  drains into the
internal jugular vein.
3.Inferior thyroid vein (variable):
– Right – drainage right or
left brachiocephalic vein.
– Left – drainage  left
brachiocephalic vein.

11. Thyroid gland
Lymphatic drainage:
■ Prelaryngeal, pretracheal and paratracheal lymph nodes.
Nerve supply:
Principally from autonomic nervous system.
■ Parasympathetic fibers – from vagus
■ Sympathetic fibers – from superior, middle, and inferior
ganglia of the sympathetic trunk
Enter the gland along with the blood vessels.

12. Normal anatomy of the recurrent
laryngeal nerve.
A) Note that on the right side the recurrent
laryngeal nerve hooks around behind the
subclavian artery.
while on the left side this nerve passes
around behind the aortic arch before
ascending in the neck.
B)When there is a vascular anomaly of the
right subclavian artery, the recurrent
laryngeal nerve no longer "recurs" around
this artery but proceeds from the vagus
nerve in a more transverse direction to the
larynx. In such a situation, the nerve is much
more likely to be damaged during surgery
unless care is taken to visualize its course in
the neck.
Thyroid gland- Surgical anatomy
R L

13. The location of 204 recurrent laryngeal nerves in dissection of 102 cadavers. Note that the recurrent
laryngeal nerve was found anterior to the tracheoesophageal groove in 42 percent of cases and within
the thyroid gland in 3(8 percent).
In both of these locations, the nerve is more prone to be damaged if its course is not carefully
visualized by the surgeon.
Thyroid gland- Surgical anatomy

14. The dramatic case of Maria Richsel, the first patient to have come to Kocher’s attention with
postoperative myxedema following total thyroidectomy. A. The child and her younger sister before
the operation. B. The changes nine years after the operation. The younger sister, now fully grown,
contrasts vividly with the dwarfed and stunted patient. Also note Maria’s thickened face and fingers,
which are typical of myxedema. Because of this and other patients with the same problem, Kocher
stopped performing total thyroidectomies. For this work, demonstrating the physiological importance
of the thyroid gland in man, Professor Kocher was awarded the Nobel prize.
Thyroid gland- Surgical anatomy
A B
MARIA
MARIA

15. PHYSIOLOGY

17. Thyroid peroxidase

21. Regulation ofThyroid Function

22. Blood Investigations
■ Thyroid-Stimulating Hormone (TSH) : essential.
If normal, no need to check freeT3 &T4 levels.
■ FreeT3 &T4 : only ifTSH level is abnormal.
■ Anti-Thyroid Antibodies (antibodies against thyroid
peroxidase & thyroglobulin) : for diagnosis of autoimmune
(lymphocytic) thyroiditis.

23. Thyroid Imaging
Chest X-ray (include thoracic inlet) :
■ Widening of superior mediastinum.
■ Tracheal deviation & compression.

24. Ultrasound scan :
■ Gives good image of thyroid &
regional lymph nodes .
■ More targeted needle aspiration
for cytology.
ComputerizedTomography (CT),
Magnetic Resonance Imaging (MRI),
Positron EmissionTomography
(PET) :
■ Only for selected cases, eg.
known malignancy, retrosternal
goitre, recurrent goitre.

25. Isotope scanning :
■ Unable to distinguish benign
from malignant.
■ Low dose of radioactive
iodine or technetium.
■ Localisation of hyperactivity
in hyperthyroid patient with
single nodule (solitary toxic
nodule) or nodularity (toxic
multinodular goitre).
■ Whole body scanning to
locate distant metastases
after total thyroidectomy
for thyroid carcinoma.

26. Fine Needle Aspiration Cytology
■ Investigation of choice for discrete thyroid swelling.
■ Diagnostic
■ Ultrasound guidance improves accuracy.
■ Cytology results :
Thy 1 : non-diagnostic.
Thy 2 : non-neoplastic.
Thy 3 : follicular (can be adenoma or carcinoma).
Thy 4 : suspicious of malignancy.
Thy 5 : malignant.

29. CLASSIFICATION
Simple
goiter
(euthyroid)
Diffuse
hyperplastic
Physiological, Pubertal, Pregnancy
Multinodular
Toxic Diffuse Graves’ disease
Multinodular
Toxic adenoma
Neoplastic Benign
Malignant
Inflammator
y
Autoimmune Chronic lymphocytic thyroiditis, Hashimoto’s disease
Granulomatous De Quervain’s thyroiditis
Fibrosing Riedel’s thyroiditis
Infective Acute (bacterial, viral, ‘subacute’),
Chronic (TB, syphilitic)
Other Amyloid

30. THYROID
ENLARGEMENT
Goitre – (Latin) guttur = the throat

31. SIMPLE GOITER
 Etiology
■ Stimulation of the thyroid gland byTSH
- Iodine deficiency
- Dyshormonogenesis
- Goitrogens (cabbage, anti-thyroid drugs)

32. SIMPLE GOITER
 Natural history (Stages)
1. Persistent growth stimulation → diffuse hyperplasia (all
lobules composed of active follicles with uniform iodine
uptake)
■Occurs in childhood in endemic goiters
■Occurs during puberty in sporadic cases ; high
metabolic demands
■Soft, large  discomfort
■TSH stimulation ceases, goiter regress, then recur
during times of stress, i.e pregnancy

33. 2. Fluctuating stimulation  mixed pattern of active & inactive
lobules
3. Active lobule – more vascular and hyperplastic  hemorrhage
 central necrosis (leaving ring of active follicles)
4. Necrotic lobules coalesce form inactive lobules
■Formation of colloid goitre
5. Continual repetition  NODULARGOITRE
■Multiple  multinodular
■Common in females (oestrogen receptors in thyroid tissue)

36.  Diagnosis
- painless, palpable nodules (smooth, firm)
- moves on deglutition
 Investigations
-Thyroid function test
-Thyroid antibodies
- Chest X-ray
- *USG,CT scan, FNAC
 Complications
- tracheal obstruction
- respiratory obstruction
- secondary thyrotoxicosis
- carcinoma

37.  Prevention and treatment
- Mostly asymptomatic and do not require operation
- Indications of surgery
- cosmetic
- relieve pressure symptoms
- patient’s anxiety
- retrosternal extension
-Types of surgery
-Total thyroidectomy
- Subtotal thyroidectomy
-Total lobectomy
- Replacement of thyroxine

40. CLINICALLY DISCRETE SWELLINGS
Isolated/solitary (70%)
Impalpable gland
Dominant (30%)
Palpable contralateral lobe
Generalised mild nodularity

41. Investigations
Thyroid function To look for toxicity
Autoantibody titres Thyroiditis
Isotope scan Functional activity
USG For FNAC and assess malignant
lymphadenopathy
FNAC Colloid nodules, thyroiditis, papillaryCA,
medullary CA, anaplasticCA, lymphoma
CXR, thoracic inlet Tracheal deviation, retrosternal extension
CT, MRI No role in first line of investigation
Laryngoscopy Mobility of vocal cords
Core biopsy Histological assessment

42. Retrosternal Goitre
■ Mostly arise from lower pole of
nodular goitre.
■ Can be asymptomatic, found on
chest X-ray.
■ Dyspnoea, cough, stridor,
dysphagia, congested veins of
face, neck & upper chest wall.
Treatment of Retrosternal Goitre :
■ Usually via cervical approach.
■ Rarely need median sternotomy.

43. Hyperthyroidism /Thyrotoxicosis
■ Grave’s Disease (diffuse toxic goitre) :
- Primary thyrotoxicosis, young females, eye signs.
- Auto-immune disease with abnormal thyroid-
stimulating antibodies (TSH-RAbs).
■ Toxic Nodular Goitre :
Secondary thyrotoxicosis, less eye signs, more cardiac
rhythm abnormalities, overactive internodular thyroid
tissue, sometimes overactive nodule.
■ Toxic Nodule : solitary overactive nodule.
■ T3-thyrotoxicosis.

44. Symptoms & Signs ofThyrotoxicosis :
Tiredness Tachycardia, bounding pulse
Irritable mood Agitation, fine hand tremors
Heat intolerance Warm moist palms, sweating
Weight loss Exophthalmos, ophthalmoplegia
Good appetite Lid lag, lid retraction
Palpitations Proximal myopathy
Diarrhea Pre-tibial myxoedema
Thyroid goitre & bruit
Grave’s Ophthalmopathy : auto-immune disorder.

45. Eye Signs ofThyrotoxicosis
1. Lid lag –VonGraefe’s sign
2. Lid retraction
Lid Retraction

46. 3. Exophthalmos
4. Chemosis (edema of conjunctiva)
5. Opthalmoplegia
6. Absence of wrinking of forehead – Joffrey’s sign

47. Treatment ofThyrotoxicosis :
■ Anti-thyroid drugs.
■ Surgery.
■ Radio-iodine.
Anti-thyroid Drugs : carbimazole 5 mg / tab or
propylthiouracil 50 mg / tab.
Start with 10 mg carbimazole 3 times / day, allow 7 to 14 days
latent interval before clinical effects, then maintain at 5 mg 3
times /day for 6 to 24 months, but failure rate 50 %.
Side-effects : agranulocytosis / allergic rash.
Propranolol (beta-blocker) 40 mg daily to reduce
cardiovascular effects of hyperthyroidism, blocks peripheral
conversion ofT4 toT3.

49. Thyroidectomy :
for toxic nodular goitre, toxic nodule, or Grave’s Disease
(failed medical control).
Pre-operative preparation :
■ euthyroid
■ oral (Lugol’s) iodine given 10 days to reduce gland vascularity,
■ laryngoscopy to check vocal cords,
■ thyroid function tests,
■ serum calcium
■ thyroid antibodies.

50. Complications :
■ haemorrhage, haematoma.
■ respiratory obstruction, tracheomalacia.
■ thyrotoxic crisis (thyroid storm).
■ voice change, laryngeal nerve palsy
■ wound infection, stitch granuloma, keloid.
■ hypocalcaemia, hypoparathyroidism.
■ hypothyroidism.
■ recurrent hyperthyroidism.

52. Radio-iodine :
■ Radio-isotope facilities available.
■ Not carcinogenic/ teratogenic.
■ Not for pregnant ladies due to congenital goitre or
hypothyroidism in newborn child.
■ Slow response, may need additional doses.
■ Require follow-up for life.
■ Appropriate for patients above 45 years old.

57. Thyroiditis
■ Chronic lymphocytic thyroiditis
(autoimmune or Hashimoto’s thyroiditis).
■ Granulomatous thyroiditis (subacute
thyroiditis or de Quervain’s thyroiditis).
■ Riedel’s thyroiditis.

58. Chronic lymphocytic
(autoimmune) thyroiditis
■ Females above 50 years old.
■ Very variable in onset, type of goitre & function.
■ Diffuse or nodular goitre with ‘bosselated’ feel.
■ Family history of other auto-immune diseases.
■ Initially may have hyperthyroidism, eventually
hypothyroidism.
■ Can be associated with papillary carcinoma &
lymphoma.
■ Raised thyroid antibodies in 85 % of cases.
■ FNAC, thyroidectomy & biopsy if in doubt or if
compression symptoms.
■ Replacement oral thyroxine if hypothyroidism.

59. GranulomatousThyroiditis
■ Caused by virus infection.
■ Sub-acute neck pain, fever, malaise, enlarged
one both lobes of thyroid gland.
■ Raised ESR but no thyroid antibodies.
■ Self-limiting disease, may have hypothyroidism.
■ Take months to recover thyroid function.
■ FNAC for diagnosis.
■ Oral prednisolone for severe acute cases.

60. Riedel’sThyroiditis
■ Very rare, probably a collagen disease.
■ Cellular fibrosis replacing thyroid follicles, with local
infiltration of vessels, nerves, muscles, etc..
■ Hard fixed nodular goitre.
■ Difficult to distinguish from anaplastic carcinoma.
■ Confirmed by biopsy.
■ Treat with high-dose steroids (prednisolone) &
thyroxine replacement.