Thymoma

Question 1

What percent of dogs with thymoma were labs and goldens in a retrospective of 116 dogs

Answer 1

38%

Question 2

What is the most common form of thymoma in cats and what is its reported metastatic rate

Answer 2

Cystic
Met rate as high as 20%

Question 3

What % of dogs and cats with a thymoma have a paraneoplastic syndrome?

Answer 3

67%

Question 4

What is the most common paraneoplastic syndrome in dogs? Cats?

Answer 4

Dogs = myasthenia gravis and megaE - 40%
Cats = exfoliating dermatitis

Question 5

Concurrent megaE and aspiration pneumonia have been reported in as many as __% of dogs with thymoma

Answer 5

40

Question 6

What percent of dogs with thymoma have a concurrent second tumor

Answer 6

27%

Question 7

What percent of dogs with thymoma are hypercalcemic

Answer 7

34%

Question 8

Neoplastic epithelial cells on cytology confirm a diagnosis. Unfortunately they are only present in __% of cases

Answer 8

61%

Question 9

Presumptive diagnosis of thymoma after cytology ranges from what percent over three studies

Answer 9

20-77%

Question 10

What cytoplasmic structures present in thymocytes can be used to aid cytologic diagnosis? Can you see them with Wright’s Giemsa stains on cytology? What about H&E on histo?

Answer 10

Hassal’s corpuscules

Can’t usually see them with Wright Giemsa

Can see them with H&E

Question 11

What is the flow Immunophenotype for thymoma

Answer 11

CD4+ CD8+

Question 12

What percentage of lymphocytes need to be CD4+ CD8+ to diagnose lymphoma

Answer 12

10%

(Will be <2% in lymphomas)

Question 13

What quadrant of the flow plot should have the highest concentration of dots with thymoma? (CD8 on the x axis, CD4 on the y axis)

Answer 13

Upper right hand quadrant

(Lymphoma will be upper left, carcinoma bottom left, normal has a little everywhere but mostly bottom right)

Question 14

MST for dogs and cats tx with surgery alone

Answer 14

Dogs: 790d (26.3m)
Cats: 1825d (60.8m)

Question 15

What are the 1 and 3y survival rates for dogs and cats tx with surgery

Answer 15

Dogs: 1y = 64%, 3y - 42%
Cats: 1y = 89%, 3y =74%

Question 16

MST for dogs tx with sx vs no sx

Answer 16

With: 635d (21.1m)
W/out: 76d (2.5m)

Question 17

RT +/- surgery: response rate and MSTs for dogs and cats

Answer 17

Response rate 75% overall

Dogs: MST 248d (8.2m)
Cats: MST 720d (24m)

Question 18

RT only: 8 dogs treated with hypofx RT, what was the overall response rate and 1y survival

Answer 18

ORR: 50%
1y survival 75%

Question 19

Periop mortality rates for dogs and cats with thymoma

Answer 19

Dogs 20-27%
Cats 11-22%

Question 20

Prognostic factors for thymoma in dogs?

Answer 20

Presence of myasthenia gravis - although not in a more recent and larger retrospective

Low percentage of intratuoral lymphocytes

Question 21

How does Masoaka-Koga stage correlate with thymoma in dogs

Answer 21

Lower stage (I or II) correlates with significantly longer STs than stages II or higher

Stage I = grossly encapsulated, no capsular invasion noted microscopically
Stage II = gross invasion to surrounding fatty tissue or mediastinal pleura; microscopic invasion of capsule
State III = gross invasion into neighboring organs (pericardium, great vessels, lungs)
Stage IVa = pleural or pericardial dissemination
Stage IVb = lymphatic or hematogenous metastasis