Mast Cell Tumors Flashcards
What breeds are predisposed to developing MCTs? What is characteristic of their development?
BRACHYCEPHALICS - Boxers, Pugs, Boston Terriers
frequently develop multiple over their lifetime associated with lower grades and metastasis
What 4 products do mast cells release upon degranulation?
- histamine
- hepatin
- proteases
- cytokines
What are 4 common results upon mast cell degranulation?
- GI ulcers
- bleeding
- poor wound healing
- anaphylactoid reactions - vasodilation, hypotension, collapse
What is used to grade MCTs? What 3 things are evaluated?
Patnaik system –> only grades MCTs arising from the skin
- cell differtentiation
- mitotic figures
- invasion into surrounding tissue
What do Patnaik grades predict?
likelihood for recurrence and metastasis
- Grade 3 = most aggressive
- Grade 2 = intermediate (most common)
- Grade 1 = least aggressive
How do MCTs typically present?
GREAT PRETENDER
- skin plaque
- nodule
- rash
- lipoma-like
What is considered the least invasive way of diagnosing MCTs? What else may be seen?
FNA –> CANNOT grade
eosinophils
When is a biopsy recommended for possible MCTs?
if FNA is non-diagnostic
What type of sample is required for grading MCTs?
biopsy
What more invasive diagnostics may be recommended in cases of MCTs? Why?
AUS + thoracic radiographs
evaluates abdominal LNs, liver, spleen, and thoracic LNs in cases of highly aggressive MCT metastasis
What type of surgical removal is recommended for MCTs? When is this treatment preferred?
excision with 2-3 cm lateral margins and 1 fascial plane deep
if metastasis is not present
When is radiation therapy recommended in cases of MCTs?
adjuvant treatment to surgery if complete margins cannot be obtained
What are 3 options for chemotherapy in cases of MCTs? When is this type of treatment indicated?
- Vinblastine
- CCNU
- alkylating agents - Cisplatin, Carboplatin, Chlorambucil
if metastasis is present, if there is a high risk of metastasis/recurrence, or if surgery or radiation are not plausible options
What are 3 important parts of supportive care in cases of MCTs?
- Prednisone - cytotoxic to mast cells, stabilizes mast cell membranes, reduces associated inflammation
- H1 blocker - Diphenhydramine
- H2 blocker - Famotidine, Ranitidine
What is the first FDA-approved drug for canine cancer in the US? How does it work?
Palladia (Toceranib)
inhibits aberrant cell signaling pathways found in MCTs (KIT, VEGFR-2, PDGFR-beta)
