Mast Cell Tumors Flashcards by jared Jensen

What is the most common malignant skin tumor in the dog

Mast Cell tumor

-it has a wide range of histology and behavior
-majority (60-81%) low or intermediate grade

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The majority (60-81%) of mast cells tumors are what grade

low or intermediate grade

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What are the breed specific significance of mast cell tumors

Brachycephalic breeds (but typically tends to not be that bad
-Boxer
-Bullmastiff
-Pug

Also: Rhodhesian Ridgeback, Vizla, Weimaraner

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What breed of dog have mast cell tumors that are typically malignant and bad (70%)

Sharpei

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T/F: Mast cells have multiple appearances on the skin

True- that is why doing cytology is so important

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What are the effect of vasoactive amines in granules of mast cell tumors

local swelling, erythema, urticaria
tumor can shrink or grow
increase in systemic histamine levels (GI ulceration)

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How might animals with very significant mast cell disease present

GI ulceration- from the high levels of histamine levels being released

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What are the visceral forms of MCT, that arent cutaneous lesions

1) Abdominal organs: Liver, Spleen, intestines (rarely lung)
2) Bone Marrow
3) Mast cell leukemia
4) Significant GI signs

very poor prognosis

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How do you diagnose Mast cell tumors

1) PE- abdominal palpation (splenomegaly, hepatomegaly) and cutaneous
2) FNA (in 10%, granules will not stain with Diff Quick)
3) Local LN palpation + FNA
4) Additional diagnostics if indicated

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When doing an FNA for mast cell tumor, how often will the granules not be stained with Diff Quick

10%- for these can send to pathologist who has a different stain but still leaves you with about 5% that dont stain

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In mast cell tumors, you should consider skipping additional pre-surgical staging if what is met *

All of the following need to be met
1) Lymph node is negative
2) No negative prognosis factors (location, breed, recurrence, ulceration, GI signs
3) Appropriately large surgery is feasible and will not require radical or very expensive procedures

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What are historical prognostic factors with mast cell tumors

1) Histologic grade: most of the high grade will spread and need to do systemic tx
Stage- worse if in LN

2) Clinical stage

3) Location: mucous membrane sites are bad: nailbed, oral cavity, perneum, prepuce (exception is conjunctiva)

4) Growth/proliferation rate/ ulceration

5) Local recurrence: selecting cells that survive

6) High number of Mitotic Index

Also: age, sex, breed

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What location of mast cell tumors is a bad prognostic factor

mucous membrane sites are bad: nailbed, oral cavity, perneum, prepuce

(exception is conjunctiva)

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What are the characteristic of canine MCT with a histologic grade of low/ intermediate

1) Low risk of metastasis
2) Aggressive local invasion of tissue
3) Still needs aggressive local therapy

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What are the characteristic of canine MCT with a histologic grade of high grade

1) Higher risk of metastasis
2) Shorter historical survival post-surgery
3) Local therapy alone suboptimal

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Do MCT on haired skin or mucous membrane has worse outcomes

Mucous membranes - 326 dd after treatment survival

Haired skin - 1374 dd after treatment survival

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With canine MCT, how is mitotic index important

tells prognosis

ex: a grade 2 with a high mitotic count is more likely to kill the patient and should be treated like a grade 3 when trying to treat

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Does the 3-tier or 2-tier grading scheme for MCT factor in mitotic count

2-tier

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When grading canine cutaneous mast cell tumors, what factors go into the cytological grading

-Number of mitotic figures
-Multinucleated cells
-Bizarre nuclei
-Karyomegaly

Mitoses >1, multinucleation and karyomegaly is the most sensitive

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What diagnostics can you use for staging a dog with MCT

-CBC/ CHEM/ UA
-Thoracic radiographs (lung rare, check out LNN) - esp if tumor is on front half of dog
-FNA of regional lymph node (even if palpates normally)
-Abdominal ultrasound
-+/- Tumor biopsy

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T/F: buffy coats are helpful in MCT staging

False
-Mastocythemia often more severe in dogs with other diseases than in dogs with MCT

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When do you consider tumor biopsy for canine MCT

if it changes how you treat
ex: deciding to amputate leg or treat
knowing if low or high grade is very important

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T/F: aspirates of structurally normal spleens/ livers are not clinically useful in managing a dog with MCT

True

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T/F: bone marrow aspirates are helpful in staging MCT if all other staging tests are negative

False

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What is the treatment choice of MCT if they are solitary

Surgical excision - needs to be wide margin incision (3cm if possible)

For canine MCT, how much do you need to surgically excise

3 cm if possible

What should you consider if you cannot do a large enough surgery to remove all of the extensions of canine MCT

radiation therapy post cytoreduction = 90% 5 year control for grade 1 or 2

When should you consider chemotherapy for mast cell tumors

for high risk or if radiation therapy / surgical excision is not an option

What ancillary therapy can you use for canine mast cell tumors

1) H1 and H2 blockers 2) Sucralfate if ulcers

T/F: Benadryl is good for dogs with mast cell tumors

false- it has really bad oral availability use other H1 blockers

With canine MCT, surgery is often a sufficient therapy if it is

low or intermediate grade MCT

How much margins should you get for canine MCT

3 cm margins in all directions may be sufficient if necessary for smaller, lower grade tumors

What radical procedures can you consider for MCT if necessary

Amputation Body wall resection

You have a grade I-II MCT with clean margins. After surgery what additional therapy(s) are recommended

None recommended - just rechecks

You have a grade I-II MCT with dirty margins. After surgery what additional therapy(s) are recommended

Additional surgery or radiation therapy

You have a grade III MCT with clean margins. After surgery what additional therapy(s) are recommended

Chemotherapy

You have a grade III MCT with dirty margins. After surgery what additional therapy(s) are recommended

Additional Surgery or Radiation Therapy AND Chemotherapy (if can only do one then Chemo is best) because we are worried it will come back AND spread

What are the pros and cons of radiation therapy for canine MCT

it is very effective in context of microscopic disease for incompletely resected, intermediate-grade MCT but if it is high grade then it is not as effective

what are the indications of using chemotherapy for canine MCT

1) Risk of metastasis: high grade tumors, unfavorable location, lymph node metastasis, multiple tumors? 2) Other therapy (surgery, RT) declined or not feasible

What chemotherapy protocol is typically used post-operatively for canine MCT

Prednisone- 2mg/kg; taper to 1 mg/kg QOD until chemo finished AND Vinblastine- 2-2.5 mg/m^2 rapid IV bolus q1-2weeks; standard is weekly x4, biweekly x4

T/F: multiple cutaneous tumors influence the outcome of the patient

False - 85% 2 to 5 year survival with surgery alone for multiple 2-6 low-intermiediate grade MCT unusual form of spread or are some dogs just programmed to make MCT

What are the two forms of feline MCT

Cutaneous and Visceral

Are feline MCT more common in males or females

Males

What breed of cat is at the highest risk of feline MCT

Siamese

Where do the majority of feline MCTs occur

60% on the head and the neck

T/F: excisions of MCTs in cats can be less aggressive than with dogs

True

How do you grade mast cell tumors in cats

if >5 mitoses in 10 HFP then it is low grade if yes, then if it has 2/3 tumor diameter >1.5cm, irregular nuclear shape, or nucleolar prominence/chromatin clusters then it is high grade

Histiocytic MCT of cats are generally seen in

young siamese cats and oriental breeds multifocal - usually on the head and neck

What are the characteristics of histiocytic MCT of cats

-young siamese cats and oriental breeds -multifocal - usually on the head and neck -Full of macrophages -Spontaneously regress

What do you do for histiocytic MCT in cats

you can just wait, often spontaneously regress but you can send to a pathologist to confirm

What are the two forms of feline visceral mastocytosis

1) Splenic (hemolyphatic) 2) Gastrointestinal

What are the characteristics of splenic MCT in cats

aint doing right cat huge, meaty spleen (15% nodular) -palpable peripheral mastocytosis common MST following splenectomy - live 18 months

Intestinal MCT in cats are typically not associated with what

mastocytosis

Characteristics of intestinal MCT in cats

Non-specific signs with a palpable abdominal mass 2/3 metastatic at diagnosis chemotherapy may improve outcome MST= 240 d in cats receiving any specific therapy

What can you use for chemotherapy for Feline MCT

-CCNU (Lomustine) - oral -Palladia

What is palladia's mechanism of action

interferes with KIT receptor tyrosine kinase expressed on normal and malignant mast cells that tells for proliferation and survival signals constitutively activated KIT and mutations in c-kit gene detected in 20-40% of canine MCT KIT expression appears more common, more intense, more likely to be cytoplasmic in high grade K9 MCT

What are the adverse effects of Palladia *

1) GI: diarrhea, vomiting, anorexia, GI bleed are the most common effects * 2) Myelosuppression- neutropenia 3) Protein-losing nephropathy 4) Muscle cramping 5) Depigmentation 6) Weight loss 7) Others rarely -liver enzymes watch for the first 6 weeks

Can Palladia be combined with chemo?

Yes- chemo dose reductions required

Can palladia be combined with radiation therapy

Yes- 75-85% response rate, MPFI = 10 months

Can palladia work for other cancers, aside from MST

Yes- may be through other kinases

What is the name of Palladia

Toceranib

isolated from the seed of Fontainea picrosperma for intratumoral treatment of canine mast cell tumors uses protein kinase C activator signalling molecules stimulates rapid tumor destruction and site healing with good cosmetic outocme

Tigilanol Tiglate

What another name for Stelfonta

Tigilanol Tiglate

What are the indications for Tigilanol Tiglate

non-metastatic cutaneous mast cell tumors non-metastatic SQ mast cell tumors located at or distal to the elbow or the hock in dogs -tumors may be any cytological grade <10cm -must be accessible to intratumoral injection