Thyroid Gland-1

Question 1

Describe demographic distribution of Hashimoto thyroiditis

Answer 1

Females 45-65 yrs, f:m ration =10:1
Most common cause of hypothyroidism In areas with adequate iodine intake

Question 2

Describe pathogenesis of Hashimoto’s thyroiditis

Answer 2

Autoimmune disease chch by breakdown of self tolerance leading to circulating auto-Abs, damage is mediated by:
1. Cytotoxic CD8+ cells
2. Cytokine-mediated cell death by helper CD4+ cells which secrete IFG, & activate macrophages
3. Binding antithyroid Abs (antithyroglobulin, antithyroid peroxidase)

Question 3

Describe G&M features of Hashimoto

Answer 3

G, diffusely & symmetrically enlarged, cut surface fleshy, pale, grey-tan
M, diffuse infiltration by lymphocytes & plasma cells with lyphoid follicles showing germinal centers,
Atrophy of follicles with diminished amount of colloid
Hürthle or Askanazy metaplasia where follicles become lined with metaplastic large cells with intensely eosinophilic, granular cytoplasm
Less commonly it is atrophic, fibrosing variant

Question 4

Possible cause & morphology of DeQuervain’s thyroiditis

Answer 4

Viral or post-viral inflammatory process
G: enlarged tender gland
M: disruption of thyroid follicles with colloid extravasation leading to PMN infiltrate which is replaced by lymphocytes, plasma cells & macrophages. Extravasated colloid triggers granulomatous reaction & foreign body giant cells.

Question 5

Describe clinical course of Hashimoto

Answer 5

1. Hypothyroidism
2. Thyromegaly absent in fibrosing variant
3. Hyperthyroidism early & transient
4. Other autoimmune dieases (B-cell non-Hodgkin lymphoma, papillary carcinoma

Question 6

Simple goiter is most commonly caused by……
Explain its pathogenesis

Answer 6

Dietary iodine deficiency
Impaired thyroid hormone synthesis leads to inc TSH causing follicular cell hypertrophy & hyperplasia followed by gross enlargement of thyroid gland

Question 7

Mention the condition of each of the follwoing:
1. Diffuse parenchymatous goiter
2. Diffuse colloid goiter
3. Multinodular goiter

Answer 7

1. Eary in disease when iodine supply is inadequate
2. When iodine supplement becomes adequate
3. After repeated cycles of hyperplasia & involution

Question 8

Mention the morphology of each of the follwoing:
1. Diffuse parenchymatous goiter
2. Diffuse colloid goiter
3. Multinodular goiter

Answer 8

1. G, diffuse gland enlargement. M, hypertrophy & hyperplasia of thyroid follicles & epithelial lining with colloid deficiency
2. G, diffuse gland enlargement with brown cystic gelatinois cut surface. M, follicles are distended with colloid with flattened epithelium.
3. G, nodular enlargement, firm consistency. Cut surface shows nodules separated by fibrous tissue. Areas of hemorrhage, necrosis, cystic degeneration & calcification may be seen. M, multiple nodules of thyroid follicles many of them filled with colloid, seprataed by fibrous tissue with variable shape & size.

Question 9

Describe clinical features of multinodular goiter

Answer 9

1. Pressure symptoms: on trachea causing dyspnea, on esophagus causing dysphagia, on great vessels causing SVC syndrome
2. In a minority of patients hyperfunctioning nodule may develop leading to hyperthyroidism
3. Malignant potential is low

Question 10

List the 3 chch features of Grave’s disease

Answer 10

Thyrotoxicosis, ophthalmopathy, dermopathy.

Question 11

Describe pathogenesis of Grave’s disease

Answer 11

Auto-immune disease due to breakdown of self-tolerance to TSH receptor & production of muliple auto-Abs:
1. Thyroid stimulatig Ig: IgG binds to TSH receptor, stmulated adenyl cyckase & thyroid hirmone release
2. Thyroid growth-stimulating Ig: against TSH receptor has been implicated in proliferation of thyroid hyroid follicular epithelium.
3. TSH-binding inhibitor Ig: prevent normal TSH binding, may dec thyroid function.
T-cell-mediated autoimmune is involved in ophthalmopathy

Question 12

GR: Occurrence of ophthalmopathy in Grave’s disease

Answer 12

As volume of retro-orbital CT & extra-ocular muscles is inc by edema, fat cells & lymphocytes mostly T-cell & accumulation of ECM.

Question 13

Describe microscopic features of Grave’s disease

Answer 13

1. There is marked epithelial hyperplasia, cells are tall columnar appear in mote than one layer with many small papillae
2. Follicles show little pale colloid with scallooped margins
3. Stroma shows inc vascularity & marked lymphocytic infiltration throughout the interstitium with formation of lymphoid follicles with germinal centers

Question 14

Describe microscopic features of 2ry toxic goiter

Answer 14

There are nodules of thyroid tissue, where thyroid follicles are lined by columnar epithelial cells, filled with colloid, scallooping at periphery
Hyperplasia of epithelium with papillae formation may be seen

Question 15

List causes of hyperthyroidism

Answer 15

Granulomatous thyroiditis, subacute lymphocytic thyroiditis, struma ovarii