Mast Cell Tumors

Question 1

What’s the most common cutaneous tumor in dogs and the SECOND most common cutaneous tumor in cats?

Answer 1

Mast cell tumors!

Question 2

What’s the mean age at presentation for dogs and cats with MCT?

Answer 2

8-9 years

Question 3

Where do cats most commonly get cutaneous MCTs?

Answer 3

Head/neck (pinnae/earbase)

Question 4

What’s the most common location for cutaneous MCTs overall?

Answer 4

Trunk (50%)

Question 5

T or F: Thoracic metastasis evaluation should always be performed, including cases of MCT.

Answer 5

False! MCTs don’t metastasize to the lungs!!

Question 6

What are the two distinct types of mast cell tumors in cats?

Answer 6

1. Mastocytic (more common) —>compact (50-90% of cases) - act benign —>diffuse (anaplastic) - aggressive (like dogs)
2. Histiocytic - characterized by histiocyte-like MCs - can spontaneously regress over 4-24 months

Question 7

What would be the best treatment for a patient with disseminated MCT disease w local tumor?

Answer 7

Adjunctive chemotherapy alone or in combination w surgery/RT to control bulky disease

Question 8

What are important patient related prognostic factors?

Answer 8

Breed (the “B’s”: boxers, bull/boston terrier, bulldog);

Systemic signs,
Location (Subungual, oral, mm associated w high grade tumors and worse px; preputial and scrotal do worse),
Stage,
Size,
Recurrence,
molecular markers,
proliferation rate,
histologic grade…

Question 9

If mast cells are gonna get crazy and metastasize, what organs will they tend to go to?

Answer 9

Liver and spleen! (They move from the local area, to the local lymph nodes, to the abdomen…)