Thoracic and Cardiovascular Questions

Question 1

How does IHC help you differentiate between SFT and Schwannoma?

(may look similar morphologically)

Answer 1

• SFT: CD34 + and S100 -
• Schwannoma: CD34 + and S100 +

The difficulty (morphologically) arises when a schwannoma is cellular.

Question 2

What is the immunohistochemical staining pattern for Schwannomas?

Answer 2

• S100: strong and diffusely positive
• EMA: highlights the perineurial cells in the capsule
• CD34: positive in the intralesional fibroblastic cells
• NOTE: GFAP and Cytokeratin may be positive

Question 3

What is the difference of immunostaining patterns between Schwannoma and Synovial Sarcoma?

Answer 3

Synovial Sarcoma

• 90% positive for cytokeratin
  
  • Note: keratin can be positive in Schwannomas with glandular differentiation, but otherwise should be negative
• EMA +
• S100: positive in 30% of cases, only focal

Question 4

What is the translocation characteristic of synovial sarcoma?

Answer 4

• t(X;18)(p11;q11)
• This is NEVER seen in a Schwannoma

Question 5

What enzyme is responsible for glycogen storage disease type I (von Gierke disease)?

Answer 5

Glucose-6-Phosphatase

25% of all GSDs

Question 6

What enzyme is responsible for glycogen storage disease type II ?

Answer 6

Lysosomal acid maltase

15% of all GSDs

Question 7

What enzyme is responsible for glycogen storage disease type III ?

Answer 7

Debranching enzymes

25% of all GSDs

Question 8

What enzyme is responsible for glycogen storage disease type IV ?

Answer 8

Branching enzyme

Question 9

What enzyme is responsible for glycogen storage disease type VII ?

Answer 9

Phosphofructokinase

Question 10

What is the most common primary malignant tumor of the heart and what is the immunophenotype?

Answer 10

Angiosarcoma–> most commonly seen within the right atrium

• FLi-1 +
• CD31 and CD34 +
• Vimentin +
• Calretinin and S100 -

Question 11

What is the immunophenotype of cardiac myxomas?

Answer 11

• Positive
  
  • Calretinin
  • CD31 and CD34
  • S100

Question 12

What is the immunophenotype of thymomas?

Answer 12

Positive:

• Cytokeratins: 34BetaE12 (HMW) and Cam5.2 (LMW)
• p63
• Lymphocytes: show a thymic phenotype
  
  • CD3, CD1a, TdT and CD99 positive
  • these lymphocytes are present even in metastatic thymomas

Note:

• CD20 positive lymphocytes can be seen in micronodular thymomas and spindle shaped thymomas

Question 13

When would you expect to see CD5 and CKIT positive in thymic-like tissue?

Answer 13

These markers are usually expressed by thymic carcinomas and rarely by thymomas.