3.3.2 Thyroid Gland Pathology

Question 1

What are some of the sources of hypothyroidism?

Answer 1

Autoimmune disease

Endemic iodine deficiency

Exogeneous goitrogenic agents

Diffuse non-toxic goiter

Ablation of thyroid gland

Question 2

What is this an image of?

Answer 2

Follicular Adenoma of Thyroid

Microscopically, the constituent cells often form uniform-appearing follicles that contain colloid (Fig. 24-15). The follicular growth pattern within the adenoma is usually quite distinct from the adjacent non-neoplastic thyroid. This is another feature distinguishing adenomas from multinodular goiters, in which nodular and uninvolved thyroid parenchyma may have similar growth patterns.

Question 3

What is this an image of?

Answer 3

Riedel struma, gross

Question 4

Why is medullary carcinoma a WMBK?

Answer 4

It has familial tendencies and can be prevented by prophylactic surgery

Question 5

What is granulomatous thyroiditis?

Answer 5

granulomatous thyroiditis or De Quervain thyroiditis, occurs much less frequently than does Hashimoto disease

Sub-acute thyroiditis is believed to be caused by a viral infection or a post-viral inflammatory process (molecular mimicry? – see I2 notes on theories of autoimmunity). The majority of patients have a history of an upper respiratory infection just before the onset of thyroiditis.

Question 6

What is this an image of?

Answer 6

Riedel struma, micro slide

Question 7

What type of HF can be a result of graves?

Answer 7

High output HF

Ventricles beating too fast leading to inability of atria to refill

Question 8

What is this an image of?

Answer 8

Diffuse toxic goiter – Graves Disease.

Question 9

What is Hashimoto’s thyroidosis?

Answer 9

Most common goitrous hypothyroidism in areas with sufficienct iodine

The vast majority of cases of autoimmune hypothyroidism are due to Hashimoto thyroiditis. Circulating autoantibodies, including anti-TSH receptor autoantibodies, are commonly found in Hashimoto thyroiditis.

Question 10

What is this an image of?

Answer 10

Follicular carcinoma

It is important to note the absence of these details because some papillary carcinomas may appear histologically to be almost entirely follicular

Question 11

What is this an image of?

Answer 11

The typical follicular thyroid adenoma is a solitary, spherical, encapsulated lesion that is well demarcated from the surrounding thyroid parenchyma (Fig. 24-14). Follicular adenomas average about 3 cm in diameter, but some are smaller and others are much larger (up to 10 cm in diameter). In freshly resected specimens, the adenoma bulges from the cut surface and compresses the adjacent thyroid. The color ranges from gray-white to red-brown, depending on the cellularity of the adenoma and its colloid content. The neoplastic cells are demarcated from the adjacent parenchyma by a well-defined, intact capsule. These features are important in making the distinction from multinodular goiters, which contain multiple nodules on their cut surface (even though the patient may present clinically with a solitary dominant nodule), produce less compression of the adjacent thyroid parenchyma, and lack a well-formed capsule.

Question 12

What is this an image of?

Answer 12

Medullary carcinoma of the thyroid

Medullary carcinoma, high power. Typical C cells, which would stain for calcitonin with an immunostain.

Question 13

What is this an image of?

Answer 13

Hashimotos Thyroiditis

Anti-microsomal antibody

Question 14

What is this an image of?

Answer 14

Papillary carcinoma

Morphology. Papillary carcinomas are solitary or multifocal lesions. Some tumors may be well-circumscribed and even encapsulated; others may infiltrate the adjacent parenchyma with ill-defined margins. The lesions may contain areas of fibrosis and calcification and are often cystic. On the cut surface, they may appear granular and may sometimes contain grossly discernible papillary foci. The definitive diagnosis of papillary carcinoma can be made only after microscopic examination. The characteristic hallmarks of papillary neoplasms include the following (Fig. 24-17):

Papillary carcinomas can contain branching papillae having a fibrovascular stalk covered by a single to multiple layers of cuboidal epithelial cells.

“Orphan Annie” or “optically clear” nuclei

Concentrically calcified structures termed psammoma bodies are often present within the lesion, usually within the cores of papillae.

Question 15

What is this an image of?

Answer 15

Hashimoto thyroiditis is an autoimmune disease in which the immune system reacts against a variety of thyroid antigens. The overriding feature of Hashimoto thyroiditis is progressive depletion of thyroid epithelial cells (thyrocytes), which are gradually replaced by mononuclear cell infiltration and fibrosis. Multiple immunologic mechanisms may contribute to the death of thyrocytes (Fig. 24-9). Sensitization of autoreactive CD4+ T-helper cells to thyroid antigens appears to be the initiating event. The effector mechanisms for thyrocyte death include the following: CD8+ cytotoxic T cell-mediated cell death: CD8+ cytotoxic T cells may cause thyrocyte destruction by one of two pathways: exocytosis of perforin/granzyme granules or engagement of death receptors, specifically CD95 (also known as Fas) on the target cell

Question 16

What is the most common invasion location of anaplastic carcinoma?

Answer 16

Trachea invasion is most common

Question 17

Endocrine hyperfunction tends to be due to?

Answer 17

Increased trophic hormone

Neoplasms of the pituitary or target gland

Exogeneous artificial hormone

Question 18

What is endemic cretenism?

Answer 18

Hypothyroidism in newborns and infants

Pathogenesis - Iodine deficiency during intraurerine life and infancy

Question 19

What is this an image of?

Answer 19

Anaplastic carcinomas of the thyroid are undifferentiated tumors of the thyroid follicular epithelium. In striking contrast to the differentiated thyroid carcinomas, anaplastic carcinomas are aggressive tumors, with a mortality rate approaching 100%.

Typically occurs with a p53 mutation

Question 20

What is Riedel’s thyroiditis?

Answer 20

Fibrous proliferation of connective tissue of thyroid extending into surrounding tissues

Question 21

What is this an image of?

Answer 21

Follicular Carcinoma

Follicular carcinomas are single nodules that may be well circumscribed or widely infiltrative (Fig. 24-18). Sharply demarcated lesions may be exceedingly difficult to distinguish from follicular adenomas by gross examination.

Question 22

What is this an image of?

Answer 22

Microscopically, medullary carcinomas (Linked to MEN2) are composed of polygonal to spindle-shaped cells, which may form nests, trabeculae, and even follicles. Small, more anaplastic cells are present in some tumors and may be the predominant cell type. Acellular amyloid deposits, derived from altered calcitonin molecules, are present in the adjacent stroma in many cases

Question 23

What is this an image of?

Answer 23

Papillary Carcinoma of the Thyroid

Question 24

What is this an image of?

Answer 24

Graves disease, micro. Note hyperplastic follicular cells, with resorption of colloid.

Question 25

Medullary carcinoma comes from what cells?

Answer 25

Derived from parafollicular C cells that release calcitonin

Question 26

What is this an image of?

Answer 26

Hashimotos thyroiditis ## Footnote Microscopic examination reveals extensive infiltration of the parenchyma by a mononuclear inflammatory infiltrate containing small lymphocytes, plasma cells, and well-developed germinal centers (Fig. 24-10). The thyroid follicles are atrophic and are lined in many areas by epithelial cells distinguished by the presence of abundant eosinophilic, granular cytoplasm, termed Hürthle cells

Question 27

What is this an image of?

Answer 27

Nodular goiter Diffuse non-toxic (simple) goiter specifies a form of goiter that diffusely involves the entire gland without producing **nodularity.** Because the enlarged follicles are filled with colloid, the term colloid goiter has been applied to this condition. This disorder occurs in both an endemic and a sporadic distribution.

Question 28

What is the clinical triad of Graves disease?

Answer 28

Hyperthyroidism owing to hyperfunctional, diffuse enlargement of the thyroid Infiltrative ophthalmopathy with resultant exophthalmos Localized, infiltrative dermopathy, sometimes called pretibial myxedema, which is present in a minority of patients

Question 29

What is the pathogenesis of Grave's Disease?

Answer 29

Auto-antibodies IgG which activate the TSH receptor

Question 30

What is this an image of?

Answer 30

Follicular adenoma ## Footnote The hallmark of all follicular adenomas is the presence of an intact, **well-formed pseudocapsule** encircling the tumor. Careful evaluation of the integrity of the capsule is critical in distinguishing follicular adenomas from follicular carcinomas, which demonstrate capsular and/or vascular invasion.

Question 31

What is this an image of?

Answer 31

The term **myxedema** is applied to hypothyroidism developing in the older child or adult.