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SBL Exam 1 WBCs, Spleen, and Thymus > Thymus > Flashcards

Flashcards in Thymus Deck (7)
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1

What is the embrologic origin of the thymus?

third (occasionally fourth) pharyngeal pouch 

2

What age-related changes occur in the thymus ?

-grows from birth to puberty

-reaches max size during puberty

-involutes, becomes replaced with fibrous/fatty tissue, following pubtery

 

*this involution is accompanied by decreased function

3

What are causes of thymic involution other than age?

-HIV infection

-severe stress

4

What are the functions of the thymus?

-T cell maturation and development of T cell central tolerance

5

What developmental abnormalities of the thymus exist?

What is their significance if any?

Thymic hypoplasia (DiGeorge syndrome)

-del 22q11

-severe cell-mediated immunte deficits, accompanied by hypoparathyroidism

 

Thymic cysts:

-uncommon

-benign and frequently incidental findings

-thymic neoplasms can appear similar to cysts; should rule out if experiencing symptoms

 

Thymic hyperplasia:

-grossly normal size, microscopic hyperplasia of the follicle

-due to germinal centers containing B cells

-can occur in myasthenia gravis and other autoimmune disorders 

 

6

What is the most common primary cancer of the thymus?

thymoma (neoplasm of thymic epitheliual cells)

7

What is the common presentation of a thymoma?

-adult >40 y/o; rare in children

-frequently found incidentally in work-up of autoimmune disease (myasthenia gravis)

-signs of impingment of mediastinal structures (40%)

-most commonly located in anterosuperior mediastinum