Mast cell tutors

Question 1

How can mast cells degranute?

Answer 1

1. IgE dependant
2. IgE independant
   -pressure, sunlight, heat, cold, excericse, stress, chemicals
   -IgG and complement

+Mrgrprx2 (G protein coupled receptor)=ANAPHYLAXTOID REACTION /pseudo-allergic reactions

Question 2

Is the p53 altered in MC tumors and correlated with survival time

Answer 2

-presence of mutant p53 protein in 13.75% to 44.6%

BUT mutant p53 immunoreactivity has NO CORRELATION with overall survival time and NOT an accurate predictor of biological behavior.

Question 3

c- kit receptor mutations are confirmed in how many cases

Answer 3

in 40% of canine mast cell tumor lines

Question 4

Why are c-kit mutations important

Answer 4

-result in constitutive (constant) activation -> unregulated intracellular signaling ->cell proliferation- >tumor formation

-RTKs (receptor tyrosine kinase) have implicated in angiogenesis and the process of metastasis

Question 5

In wich breeds we have good prognosis with MCT

Answer 5

Boxer + Pug (hind limbs, multiple lesions )

Question 6

What is different between well differentiated and poorly differentiated

Answer 6

Well differentiated: slow grow + hairless + solitary + for months
Poorly differentiated: rapid grow + ulcerated + pruritic + often satellite lesions +/- go to LFN

Question 7

What are signs suggestive of agressive lesions

Answer 7

1) Rapid growth
2) Local irritation/inflammation
3) Local infiltration/poor demarcation from adjacent tissues
4) Ulceration
5) Satellite nodules
6) Paraneoplastic signs

Question 8

Name special stains

Answer 8

1. toluidine blue,
2. pinacyanol,
3. Wright’s or Wright-Giemsa stain (good to evaluated granules) whereas Diff-Quick best for nucleus

Question 9

In wich species is histiocytic subtype seen and what is apperanace

Answer 9

-Siamese kitten
- often has a granulomatous appearance (many histio) -> confirm only by TEM

Question 10

What does staging do

Answer 10

• defines nature (degree) and extent (LFN, liver, spleen, BM, satellite lesions)
• recommended if extensive or expensive tx is planned or a poorly differentiated or evidence of metastasis
• Most MCT are unlikely to metastasize
• Full staging = FNAs of draining LFN + Abd USG

Question 11

Can we have mast cells in lymp nodes

Answer 11

• Up to 25% normal dogs have few normal masts in LFN ->up to 0,1% cells in healthy; up to 0,55% in CAD
• Plus, the cytologist may not tell if they are reactive or neoplastic.

Question 12

How can we assume mast cells in LN are metastatic

Answer 12

->as a general rule, if mast cells appear in clusters or sheets -> suggestive of metastatic disease.
-> increased nº or abnormal morphology or effacement of normal LFN architecture on histology - all point to metastatic disease

Question 13

Can we use buffy coat for diagnosis of MCT

Answer 13

• Buffy coat smears: probably poor value in dogs (questionable)

BUT appropriate in CAT with certain presentations of mast cell disease ->may incerase peripheral mast - bad PX!!

Question 14

What is recommended if nodal metastais is seen

Answer 14

full staging w/ Abd US (w/ FNA of spleen and liver)
+ FNA of BM
+ Lung XRAY

Question 15

Explain Grade I of Patnaik classification

Answer 15

well-differentiated- at dermis and interfollicular spaces
<10% metastasis
-slow grow, ↓death

Question 16

Explain grade II Patnaik

Answer 16

intermediate-@ lower dermis + SC
-5-22% metastasis
-some can be cure with excisional surgery alone
-17–56% die of due to local treatment failure or metastatic disease
- Unpredictable behaviour
-subjective histopathological grading between pathologists -difficult to give Px

Question 17

Grade III Patnaik

Answer 17

anaplastic- at SC + deeper tissues
>80% metastasis
-aggressive growth
-high recurrence
-↑ death

Question 18

Kiupel 2 tier grading system HIGH vs LOW

Answer 18

High grade:
- 7 or > mitosis/10 hpf
- at least 3 multinucleate (3 or more nuclei) cells/10 hpf
- at least 3 bizarre nuclei/ 10 hpf
- Karyomegaly (i.e. nuclear diameters of at least 10% of neoplastic cells vary by at least two-fold)

Question 19

What are other bad prognostic criteria

Answer 19

• LFN metastasis (!! interpretation is challenging)
• Anatomic location
  -mucocutaneous junctions + inguinal region: more malignant regardless of histological grade, but this is controversial
  -viscera or BM
• Clinical features and recurrence after treatment

Question 20

How can c-kit mutation be confirmed and has it correlation with good or bad prognosis

Answer 20

• IHC or PCR

-increased metastasis risk increased local recurrence incerased tumor proliferation index

• RTK c-Kit is dysregulated in 15–40% of canine MCT

Question 21

Name proliferation markers

Answer 21

1. Mitotic index (no mitosis / 10hpf)
2. Ki-67 protein
3. AGNOR
4. PCNA

Question 22

What is AgNOR

Answer 22

Argyrophilic Nucleolar Organizing Region-associated proteins
- bind silver molecules, thus can be visualized using a silver-based histochemical stain
- the incresed nº of AgNOR dots/nucleus the more rapidly is cell division = more proliferative tumor

Question 23

What is Ki-67

Answer 23

marker for proliferation, expressed during the cell cycle
- IHC
-increased Ki-67 = more proliferative tumor

Question 24

What is PCNA

Answer 24

Proliferating Cell Nuclear Antigen = protein required for DNA synthesis.
- associated with cell proliferation

Question 25

What are surgical recommendations for MCT removal

Answer 25

* 2cm/1 fascial plane recommended for tumors <4cm * 3cm/deep fascial plane to grade III * < or = 0.5 cm @ distal limbs -> 2-year recurrence-free rate of 93%.

Question 26

What are 1st and 2nd line of chemoth

Answer 26

1st-line: vinblastine and prednisolone 2nd-line: lomustine

Question 27

What is recommended supportive th

Answer 27

* medication to counter the effects of histamine -H2 antagonists to treat gastric ulceration: cimetidine (4 mg/kg PO q8h), ranitidine (2 mg/kg PO q12h), famotidine (0.5–1mgkg−1 PO q12–24h) -proton pump inhibitor omeprazole (0.5–1mgkg−1 PO q24h) -H1 antagonists to decrease adverse effects of histamine release on peripheral vasculature and wound healing: diphenhydramine (2–4mg kg−1 PO q12h). * sucralfate is recommended in cases with GI signs.

Question 28

Are COX-2 ihibitors indicated

Answer 28

* Cox 2 is overexpressed in high grade mastocytoma

Question 29

Indication of toceranib phosphate

Answer 29

* approved for use in recurrent, nonresectable grade II/III -> no need to test for c-Kit mutation * Side effects: GI, neutropenia, muscle cramping

Question 30

Indications for masitinib

Answer 30

* approved for use in nonresectable grade II/III MCT with established c-Kit mutation * Side effects: GI, neutropenia, muscle protein losing nephropathy

Question 31

What are 2 clinical presentation of MCT in cats

Answer 31

1. Mastocytic a)nodule b)plaque c)multiple SC nodules 2. Histiocytic

Question 32

Desribe mastocytic MCT disease in cats

Answer 32

-10 years >>> kittens can be affected -Male and Siamese ++ head & neck -3 types +++ Nodule: solitary, firm, well-circumscribed, hairless or ulcerated, dermal Plaque: flat, pruritic, resemles eosinophilic granuloma (may be multiple) Multiple SC nodules

Question 33

How is mastocytic MCT subdivided

Answer 33

-well-differentiated (formally compact form): 50–90% of cases, + benign -pleomorphic (formally diffuse form): histologically + anaplastic; clinically + malignant, poor Px

Question 34

What are prognostic factors in cats

Answer 34

-multiple cutaneous MCT carry a more guarded prognosis (contrary to dog) -pleomorphic phenotype is worse -KIT immunoreactivity score -MI -Ki67

Question 35

High vs low grade in cats

Answer 35

Question 36

Histiocytic MCT in cats

Answer 36

-From 2M-old to <4y Siamese -kittens (2 litters, same mum) suggesting a genetic influence -multiple firm, pink papules and nodules @ head and pinnae -eventually spontaneously regress. -Easy to confuse with histiocytoma or lymphoma!!!

Question 37

MCT in ferrets

Answer 37

-44% of all cutaneous and subcutaneous neoplasms in ferrets -typically benign and neither local recurrence after surgical excision nor metastatic disease has been reported -Histologically, most ferret MCTs consist of well‐differentiated mast cells where mitotic figures are rare and, similar to cats, few eosinophils are present - there was no relationship between Kit immunostaining and prognosis

Question 38

MCT in horses

Answer 38

- 3.4% of all cutaneous equine tumours (2006) -head as a single nodule; -multiple lesions are not indicative of malignant disease and may occur in any anatomical area of the skin -Arabian horses at risk, but no sex predilection -follow a benign disease course and appear histologically well differentiated with a low mitotic rate -Aberrant cytoplasmic Kit staining is detected by immunohistochemistry in 15% of cases but is not correlated to malignant disease or a worse prognosis, -Surgery alone is curative

Question 39

MCT in bovine

Answer 39

-less than 1% of all bovine neoplasms -neoplastic mast cells appear well differentiated in cattle, even in cases with metastasis

Question 40

MCT in pigs

Answer 40

-from well differentiated, benign lesions to malignant and metastatic cancer

Question 41

Name 4 MC driven disorders in humans

Answer 41

1- Urticaria 2- type I allergy 3- Mastocytosis 4- MC activation syndrome (MCAS)

Question 42

In a study by Daniel, 2019 how did the tumor collagen index influenced mortality and survival in MCT

Answer 42

-quantity of intratumoral collagen was LOWER in high-grade MCT -dogs with low Colagen MCT had incerased risk of death and shorter survival -ECM plays a protective role?

Question 43

Locations of MCT in horse

Answer 43

Head (lip, nostril, jaw, periorbital area) neck, trunk and limbs (near joints) Hard, immovable Also, nasal cavity, trachea, conjunctiva, sclera, nictitans, globe.