The thyroid gland is located in the neck and produces hormones that regulate metabolism. It has two lobes connected by an isthmus. The gland contains follicles that produce thyroid hormones. Hashimoto's thyroiditis is the most common cause of hypothyroidism. It is an autoimmune disease where the immune system attacks the thyroid, destroying follicles and causing lymphocytic infiltration. This leads to decreased thyroid hormone production and symptoms like weight gain and fatigue. Treatment involves thyroid hormone replacement therapy.

1. THYROID ANATOMY AND
PATHOLOGY
Muni Venkatesh.P
Group 2

2. ANATOMY
 It is an endocrine gland.
 Located in the anterior region of the neck at C5-
T1, overlays 2nd – 4th tracheal rings.
 Anterior & lateral to larynx and trachea.
 Average width: 12-15 mm (each lobe)
 Average height: 50-60 mm long
 Average weight: 25-30 g in adults.

4.  It has two lobes,
which are
connected by
isthumus.
 1.25 cm x 1.25 cm
 Crosses tracheal
rings between 2
and 4
 Occasionally
absent
 Pyramidal lobe
may be present

5. PYRAMIDALLOBE
 Often ascends from the isthmus or the adjacent
part of either lobe up to the hyoid bone
 May be attached by a
fibrous/fibromuscular
band “levator” of the
thyroid gland.

7. STRUCTURE
 Gland is covered by
capsule.
 Capsule extensions within
the gland form septae,
dividing it into lobes and
lobules.
 Lobules contains
follicles(structural units of
the gland).
 Follicles are surrounded by
dense plexuses of
fenestrated capillaries,
lymphatic vessels, and
sympathetic nerves.

8.  Lobules are attached to cricoid cartilage by
ligaments
 Medial surface adapted to larynx and trachea
 Lobes related posteriorly to the esophagus
 Posterolateral surface
a. related to carotid sheath
b. overlaps carotid artery.

9. Epithelial cells = 2
types:
 principal (ie:
follicular) – formation
of colloid
(iodothyroglobulin)
 parafollicular (ie: C
cells -clear, light), lie
adjacent to follicles
w/in basal lamina 
produce calcitonin

10. MUSCULARLANDMARKS
a. Sternocleidomast -
oid muscles lie
laterally
b. Longus colli
muscles lie
posteriorly
c.Strap muscle,
omohyoid muscle and
sternohyoid muscles
lie anteriorly

11. BLOODSUPPLY
 Highly vascular gland supplied by four large
arteries
a. Right & Left inferior thyroid artery
b. Right & Left superior thyroid artery
 Drained by Right & Left superior, middle and
inferior thyroid veins
a. Veins arise from plexus
b. on anterior surface of gland
c. Extend over anterior surface of
trachea

13. LYMPHVESSELS
1. In interlobular connective tissue between lobes.
2. Connect with network in wall of gland
3.Terminate in thoracic and right lymphatic ducts.

14. AUTONOMICINNERVATION
a.Cervical portion
of sympathetic
trunk
b.Parasympathetic
fibers arise from
Vagus X

15. DISEASESOFTHETHYROIDGLAND
 Congenital diseases
 Inflammation
 Functional abnormality
 Diffuse and Multinodular goiters
 Neoplasia

16. INFLAMMATION
Thyroiditis
 Acute illness with pain
 Infectious
 Acute
 Chronic
 Subacute or granulomatous (De Quervain’s)
 Little inflammation with dysfunction
 Subacute lymphocytic thyroiditis
 Fibrous (Riedel) thyroiditis
 Autoimmune
 Hashimoto thyroiditis

17. HASHIMOTOTHYROIDITIS
 Most common cause of hypothyroidism
 Autoimmune, non-Mendelian inheritance
 45-65 years, F:M = 10-20:1
 Painless symmetrical enlargement
 Risk of developing
 B-cell non-Hodgkin’s lymphoma
 Other concomitant autoimmune diseases
Endocrine and non-endocrine

19. HASHIMOTOTHYROIDITIS
PATHOGENESIS
 Immune systems reacts against a variety of
thyroid antigens
 Progressive depletion of thyroid epithelial cells
which are gradually replaced by mononuclear
cells → fibrosis
 Immune mechanisms may includes:
 CD8+ cytotoxic T cell-mediated cell death
 Cytokine-mediated cell death
 Binding of antithyroid antibodies → antibody
dependent cell-mediated cytotoxicity

20. Outcome: progressive depletion follicular cells with
replacement by mononuclear inflammation and

22. HASHIMOTOTHYROIDITIS
 Diffuse
enlargement
 Firm or rubbery
 Pale, yellow-tan,
firm & somewhat
nodular cut surface

23. HASHIMOTOTHYROIDITIS
 Massive
lymphoplasmcytic
infiltration with
lymphoid follicles
formation
 Destruction of
thyroid follicles
 Remaining follicles are
small and many are
lined by Hurthle cells
 Increased interstitial
connective tissue

24. FUNCTIONALABNORMALITY
 Hyperfunction
  in level of hormone → toxic effects
Due to:
Diffuse hyperplasia
Hyperfunctioning multinodular goiter
Hyperfunctioning adenoma
Subacute lymphocytic (painless)
thyroiditis

25. FUNCTIONALABNORMALITY
 Hypofunction
  in level of hormone → impair development in infants
and slowing of physical and mental ability in adults
 Due to:
 Postablation
 Surgery
 Radiation
 Autoimmune thyroiditis
 Drugs
 Dyshormonogenetic

26. SYMPTOMS
 Myxedematous psychosis, weight
gain, depression, mania, sensitivity to heat
and cold, paresthesia, chronic fatigue,
panic attacks, bradycardia, tachycardia,
high cholesterol,reactive hypoglycemia,
constipation, migraines, muscle weakness,
joint stiffness, menorrhagia, cramps,
memory loss, vision problems, infertility
and hair loss.

28. LABORATORY
 Serum TSH level.
 Free serum T3 and T4.
 Detection of anti-thyroid peroxidase
autoantibody.
 Detection of TSH receptor-blocking antibody.
 By ultrasound.

30. TREATMENT
 The normal thyroid
hormone level is
maintained by giving
thyroxine therapy
which will also help to
reduce side of thyroid
gland.
 Complications of
Hashimoto’s thyroiditis
are changes in
menstrual cycle,
increse risk of
abortions etc.