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SA DX & TX II > Exam 2 - Mast Cell Tumors > Flashcards

Exam 2 - Mast Cell Tumors Flashcards

1
Q

what is the most common skin tumor in the dog?

A

mast cell - 16-21% of all skin tumors

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2
Q

what breeds are predisposed to mast cell tumors?

A

brachycephalic breeds, labs, beagles, & schnauzers

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3
Q

what is the average age of an animal affected by a mast cell tumor?

A

9 years old - but can be seen in dogs as young as 3 weeks old

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4
Q

what are the 3 forms of mast cell tumors in dogs?

A
  1. dermal form
  2. visceral form
  3. intestinal form
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5
Q

what are the clinical signs of dermal mast cell tumors in dogs?

A

variable signs

release of bioactive constituents result in - gi ulcers, hypotension, coagulation abnormalities, & delayed wound healing

solitary vs. multiple masses

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6
Q

what is darier’s sign?

A

local reaction seen when a mast cell tumor degranulates

urticaria, erythema, hives, & edema

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7
Q

what is shown here?

A

dermal MCT showing darier’s sign - urticaria, edema, erythema, & hives

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8
Q

where do MCT almost never metastasize to?

A

the lungs

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9
Q

what are the common sites of metastasis of mast cell tumors?

A

lymph nodes, spleen, liver, & bone marrow

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10
Q

what is the prognosis of a low grade mast cell tumor? what is the rate of metastasis seen?

A

MST > 2 years

<18% metastatic rate

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11
Q

what is the prognosis of a high grade mast cell tumor? what is the rate of metastasis seen?

A

MST < 4 months

metastatic rate >70%

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12
Q

what are the characteristics that signify a high grade mast cell tumor?

A

mitotic index >/= 7

> 3 multinucleate cells in 10 HPF

> 3 bizarre nuclei in 10 HPF

karyomegaly - abnormally enlarged cell nucleus, at least 10% of cells that have a 2 fold increase in size to qualify for this

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13
Q

what is the 2 tier grading system of mast cell tumors? what does it apply to?

A

only applies to cutaneous MST - 96.8% consistency & 99.3% agreement

broken up into low grade (90% of tumors we see are considered to be low grade) & high grade

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14
Q

using WHO staging, what is a stage 0 MCT?

A

1 tumor that is incompletely excised from the dermis, identified histologically without regional lymph node involvement

0a - no systemic signs
0b - systemic signs present

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15
Q

using WHO staging, what is a stage I MCT?

A

1 tumor confined to the dermis without regional lymph node involvement

1a - no systemic signs
1b - systemic signs present

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16
Q

using WHO staging, what is a stage II MCT?

A

1 tumor confined to the dermis with regional lymph node involvement

IIa - no systemic signs
IIb - systemic signs present

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17
Q

using WHO staging, what is a stage III MCT?

A

multiple dermal tumors

large, infiltrating tumors with or without regional lymph node involvement

IIIa - no systemic signs
IIIb - systemic signs present

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18
Q

using WHO staging, what is a stage IV MCT?

A

any tumor with distant metastasis including blood or bone marrow involvement

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19
Q

how are cutaneous MCT diagnosed?

A

FNA - often bleed & swell

biopsy - pre-medicate the animal with benadryl, famotidine, +/- steroids to avoid side effects of histamine release

IHC

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20
Q

what special stains are used for diagnosing MCT?

A

wright stain commonly used

t-blue, vimentin, a-1-antitrypsin, & CD117 (c-kit)

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21
Q

what is the mast cell tumor prognostic panel? what is included?

A

a panel of factors known to help predict MCT behavior - has to be done on biopsied tissue

Ki67, AgNOR, c-kit (staining pattern & PCR for mutations)

c-kit - will tell you how much you have on the surface, but doesn’t tell you if it is mutated!!!!

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22
Q

what staging is used for MCT?

A

bloodwork - cbc, chemistry, & UA

regional lymph node aspirates

chest rads

abdominal ultrasound

23
Q

what are some prognostic factors evaluated for MCT?

A

histological grade - best predictor for dermal tumors!!!!!

clinical stage

location - mucocutaneous junctions are worse

cell proliferation

growth rate

recurrence - always will come back more aggressive than the first time

systemic signs - indicates more severe disease/stage

breed of the animal - boxers tend to get low grade MCT & labs tend to get high grade MCT

c-kit mutation - exxon 11 mutations have a worse prognosis vs no mutations or exxon 8 mutation

tumor size - bigger the tumor, the harder it is to get local control

24
Q

how is surgery used to treat cutaneous MCT?

A

premedicate the animal - diphenhydramine & steroids

get 2-3cm margins & 1 fascial plane deep - look for enlarged lymph nodes

may use cytoreduction or amputation

25
Q

when is radiation therapy used for cutaneous MCT?

A

only in microscopic disease!!!!!!!! worried about massive anaphylactic reaction due to mass degranulation of tumor, so used after surgery to clean up margins

definitive therapy with 85-95% cure rate for grade I tumors & 50% 1 year control rate for grade III tumors

26
Q

what long term radiation effects are seen in animals with cutaneous MCT?

A

depigmentation at most intense site of treatment, hyperpigmentation around the general area, alopecia, & hair changes colors in the areas that received the least amount of radiation

27
Q

what chemo drug will you never use for an animal with cutaneous MCT? why?

A

doxorubicin - main side effect is mast cell degranulation causing a hypersensitivity like reaction

28
Q

when is chemo used for MCT? what drugs can be used?

A

high grade tumors, microscopic setting after surgical removal, & non-resectable tumors

vinblastine (blasts mast cells, #1 drug), lomustine, cyclophosphamide, & chlorambucil - use all concurrently with prednisone!!!!

all drugs here are cytotoxic - will kill cells, always start with a cytotoxic drug

29
Q

how does torceranib phosphate (palladia) work for treating cutaneous MCT? what are some side effects associated with it?

A

good class of drug for treating MCT with c-kit mutations - receptor tyrosine kinase inhibitor that inhibits VEGF, PDGFR, c-kit, & FGFR

gi ulcers, muscle pain, neutropenia, thrombocytopenia, & proteinuria

30
Q

how does masitinib mesylate (kinavet) work for treating cutaneous MCT? what are some side effects associated with it?

A

receptor tyrosine kinase inhibitor that inhibits PDGFR, c-kit, & mutated FGFR

gi ulceration, neutropenia, & proteinuria

31
Q

what are some treatment options for ancillary therapy for a patient with MCT?

A

diphenhydramine, h-2 blockers, sucralfate, pain meds, & protamine

32
Q

what is the MST for intestinal mast cell tumors in dogs & cats with aggressive therapy? why?

A

<120 days - very aggressive tumor type with a very high metastatic rate

33
Q

what treatment is recommended for intestinal mast cell tumors in dogs & cats?

A

surgical removal with 10cm margins & always followed with chemotherapy

34
Q

what is the visceral form of MCT in cats?

A

spleen, liver, lymph nodes, & bone marrow are involved

35
Q

what is the cutaneous form of MCT in cats?

A

of the dermis - head & neck, non-haired areas, fleshy, & often in multiples

36
Q

what cat breed/signalment is predisposed to cutaneous MCT?

A

young male siamese cats

37
Q

what is the 2nd most common skin tumor in cats?

A

cutaneous mast cell tumor - makes up 20% of all skin tumors

38
Q

what is the typical age of a cat seen with a mastocytic cutaneous MCT?

A

10 years old - similar to MCT found in dogs

39
Q

what is the typical age of a cat seen with a histiocytic cutaneous MCT?

A

young cats - 2.4 years old, histiocytic mast cells that act like histiocytomas in dogs, look like eosinophilic plaques

need to do a biopsy to differentiate mast cell tumor from rodent ulcer

40
Q

T/F: cats rarely show systemic signs with cutaneous MCT

A

true

41
Q

what are some clinical signs associated with visceral MCT in cats?

A

weight loss, anorexia, diarrhea, melena, vomiting, collapse, & death

42
Q

what clinical signs are seen with cutaneous MCT in cats?

A

rare to see systemic signs - usually a lesion noticed by the owner that may be ulcerated

43
Q

how are MCT diagnosed in cats?

A

FNA or biopsy

pre-medicate if aspirating the spleen - full of MAST CELLS!!!!!

44
Q

how are MCT staged in cats?

A

CBC/chemistry/UA

FNA of regional lymph nodes

chest rads & abdominal ultrasound

45
Q

what is the treatment used for cutaneous MCT in cats?

A

surgery - narrow margins are necessary

benign neglect - tumors often regress

46
Q

what is the MST of visceral MCT in cats treated with splenectomy/surgery?

A

11-24 months

47
Q

is chemotherapy used in cats with visceral MCT? what drugs?

A

it is but it is untested - used prednisolone, diphenhydramine, famotidine & watch it

vinblastine, lomustine, & chlorambucil

48
Q

T/F: there is no worked out grading system for any type of MCT apart from dermal MCT

A

true - no grading established for tumors in the SQ

49
Q

what organs are most commonly implicated in the visceral form of MCT?

A

liver & spleen

50
Q

what is the only form of MCT that is the same in dogs & cats?

A

intestinal MCT

51
Q

T/F: if CD117 is negative, it is not a mast cell tumor

A

true - all MCT will stain with CD117

52
Q

what kind of receptors are tyrosine kinase? why are they a good target for drug therapy?

A

growth factor receptors

95% of protein interactions in the cell will not be affected by the inhibitor

53
Q

instead of grading in cutaneous MCT in cats, what is provided instead?

A

whether the tumor is compact vs. diffuse

compact - lower grade, well circumscribed

diffuse - infiltrative, higher grade

54
Q

why is a splenectomy done for a cat with visceral MCT?

A

every time the animal jumps/is picked up/squeezed - the mass degranulates further exacerbating clinical signs

SA DX & TX II (62 decks)

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