Mast Cell Tumors Flashcards

1
Q

What is the most common cutaneous tumor in cats?

A

1. Basal cell tumor
2. Mast cell tumor

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1
Q

What is the most common cutaneous tumor in dogs?

A

MCT

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2
Q

True or False: Mast cell tumors are generally very treatment responsive

A

TRUE

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3
Q

What dog breeds are predisposed to getting mast cell tumors?

A
  • The B breeds, boxers and brachycephalics
  • Boxers
  • Bulldogs
  • Boston terriers
  • Bull terrier

(Luckily they get lower grade/less aggressive variants of MCTs)

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4
Q

What cat breeds are predisposed to getting mast cell tumors?

A
  • Siamese cats
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5
Q

Why are MCT’s known as the “great imitators”?

A
  • Lots of different appearances
  • Ill defined, soft and edematous (often misdiagnosed as lipoma)
  • Tends to be solitary but can have multiple on presentation
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6
Q

Where are cutaneous MCTs usually located on dogs vs cats?

A

Dogs: Trunk and extremities
Cats: Head and Neck

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7
Q

What is the Darriers sign?

A
  • Disturbance of mast cell tumors leads to degranulation causing erythema, swelling, anaphylaxis and hypotension

(This is why we pre med with Diphenhydramine before poking with needle for FNA)

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8
Q

What are the effects of Degranulation with MCTs?

A
  • GI ulcers (histamine increases HCL in stomach)
  • Delayed wound healing / Surgical dehiscence
  • Hypotension
  • Local hemorrhage
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9
Q

How would you work up and stage for a MCT?

A

1. MDB
2. Regional LN aspirate

(Only 2 tests needed to stage if no negative prognostic factors and amendable to wide excision! No thoracic rads needed bc doesn’t met to lungs!)

  1. ABD Ultrasound to check mets to liver and spleen
  2. BM aspirate if visceral MCT
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10
Q

What can be found on AUS when working up and staging for a MCT?

A
  • Looking for mets to liver and spleen
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11
Q

List the histological classifications of MCTs in cats

A

1. Mastocytic (most common)
(2 subtypes: Compact of Diffuse, compact most common in cats)

  1. Histiocytic (seen in young Siamese) - rare
  2. Splenic / Visceral MCT
  3. Intestinal MCT
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12
Q

What is known about histiocytic MCTs in cats?

A
  • Seen in young siamese cats
  • Requires wide surgical excision
  • Can spontaneously regress over 4-24 months (ok to wait it out and see in this case only)
  • Rare overall (most common is the mastocytic type)
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13
Q

A siamese cat is presenting for recheck of a cutaneous lesion on the neck, first noticed 5 months ago. On PE today, there is no evidence of a mass. Which type of MCT in cats has the possibility of spontaneous regression?

A. Compact mastocytic MCT
B. Histiocytic MCT
C. Splenic / Visceral MCT
D. Intestinal MCT

A

B. Histiocytic MCT

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14
Q

What systems are used to grade MCTs in dogs?

A
  • Patnaik 3 tier system (Grade 1,2,3)
  • Kiupiels 2 Tier system (Low grade 2 vs High grade 2)
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15
Q

Your biopsy came back as a Grade 1 MCT. What does this mean?

A
  • Well differentiated
  • No mitotic figures
  • Minimal stromal rxn or necrosis
16
Q

Your biopsy came back as a Grade 2 MCT. What does this mean?

A
  • 0-2 mitotic figures/ hpf
17
Q

Your biopsy came back as a Grade 3 MCT. What does this mean?

A
  • Poorly differentiated
  • 3 to 6 mitotic figures
  • Areas of hemorrhage, edema, necrosis and hyalinized collagen
18
Q

What locations of MCTs are associated with a poor prognosis?

A
  • Subungual (toe)
  • Oral/Perioral (muzzle region)
  • Preputial & scrotal do worse
  • Visceral MCT
  • Bone marrow MCT
19
Q

Treatment options for a MCT in a dog?

A
  • Wide surgical excision with 2-3cm margins + fascial plant deep = gold standard if localized skin tumor
  • If comes back low grade = tx done
  • If comes back high grade = add Vinblastine as adjunct chemo + Prednisone
  • If localized but non-resectable: Neoadjuvant chemo + sx
  • Palladia
20
Q

You planned a curative excision for a cutaneous MCT in a dog, but biopsy comes back as unsuccessful with incomplete margins. How do you proceed with treatment?

A
  • Scar revision via surgical excision of scar with 2-3cm margins
21
Q

Before considering starting treatment for a MCT, what test can be done in high risk dog breeds that will help determine prognosis?

A

MCT prognostic panel via biopsy to determine CKIT mutation

CKIT mutation favors palliative tx vs surgery

22
Q

What chemotherapeutics yields long survival times in dogs with MCTs?

A

Vinblastine + Prednisone

23
Q

________ is an intralesional chemotherapy approved for all grades of mast cell tumors

A

Tigilanol Tiglate (Stelfonta)

not a #1 line tx option, used sometimes for non-resectable MCTs

24
Q

List the negative prognostic factors associated with MCTs in dogs

A
  • LOCATION predicts aggressiveness (subungual, oral, scrotal, spleen, liver or BM is worse)
  • CKIT Mutation
  • Tumors > 5cm
  • Recurrance
  • Histo grade via Kiupel grading scale
25
Q

How does surgical excision of a cutaneous MCT differ in dogs vs cats?

A

Wide surgical excision with 2-3cm margins + fascial plant deep usually NOT required in CATS since most are compact mastocytic MCTs

26
Q

Where do cutaneous MCTs like to metastasis to?

A

Liver and spleen

Do AUS!