Dermatology skin tumours and mast cell tumours

Question 1

What are the different types of epithelial tumours

Answer 1

Cutaneous papillomas; can see oral ones in dogs, these regress

Basal cell tumour: common

Squamous cell carcinoma

Question 2

Characteristics of basal cell tumour

Answer 2

Middle aged animals
Head and neck typically
May be pigmented
Usually benign; cure via surgery

Question 3

What is the most common pigmented mass on the head of a cat

Answer 3

Basal cell tumour NOT melanoma

Question 4

Key difference between SCC on the nose vs other parts of body in dogs

Answer 4

Ones elsewhere don’t usually metastasise; local invasion more of an issue

In nasal planum SCCs in dogs = highly malignant as well as locally invasive
[cats not that malignant]

Question 5

KEy difference in aetiology of SCC of nasal planum in dogs vs cats

Answer 5

In cats = related to UV light exposure
In dogs = genetic; see more in retrievers and collies; quite metastatic

Question 6

What do SCC look like and where do they arise

Answer 6

Arise in lightly pigmented parst of body, assocaited with UV light exposure
Can look like cauliflower lesion or more like a non-healing ulcer

Question 7

How can we treat superficial SCC of nasal planum in cats

Answer 7

Strontum brachytherapy

Could also try photodynamic therapy

Question 8

How does SCC of nail bed present

Answer 8

Sore swollen toe; often misdiagnosed as a nail beg infection but antibiotics don’t work

Question 9

Where might adnexal tumours come from

Answer 9

Sebaceous gland
Hair follicle
Perianal/hepatoid gland adenoma

Question 10

What must be on our differential list for any epithelial lesion which is ulcerated or erosive

Answer 10

Squamous cell carcinoma

Question 11

Characteristics of primary cutanoue lymphoma

Answer 11

T cell
PResents as multiple cutaneous nodules/plaqes
Aggressive with widespread disseminatino
Poor prognosis

Question 12

PResentation of epitheliotrophic lymphoma

Answer 12

Can manifest in many ways
Often intesnse pruritis and scale
Can get nasal planum depigmentation

(there is also a muco-cutaneous form which looks like proliferating red velvet tissue through the mouth)

Question 13

Treatment of epitheliotrophic lymphoma

Answer 13

Poor
Don’t respond to chemo
CAn give steroids to help pruritis
Mouth lesions can have radiotherapy and respond well

Question 14

WHat is a plasmactyoma

Answer 14

Solitary skin tumour with benign behaviour; cure via sugerical excision

Question 15

What is canine cutaneous histiocytoma

Answer 15

Common benign tumour of young dogs; see rapidly growing lesion on head mostly
Then spontaneous regression related to cytotoxic T lymphocte influx

Question 16

How does reactive histiocytosis present

Answer 16

Can be skin only
Or systemic
INfiltration with histiocytes/antigen-presenting cells

Lesions wax and wane but slowly proress

Question 17

What breeds are predisposed to disseminated histiocytic sarcoma and what is the prognosis like

Answer 17

Bernese mountain dogs
Retriever
Rottweiler

Very poor prognosis

Question 18

BReed predisposition for histiocytic sarcoma

Answer 18

Flat coated retriever

Question 19

What organism is associated with oesophageal sarcoma

Answer 19

Spirocerca lupi encysting there
Thought to be related to chronic inflammation aetiology

Question 20

Feline injection site sarcoma characteristics

Answer 20

YOung animals
Very aggressive
High rate of local recurrenace so need huge margins

Must consider whenever we see a cat with mass betewen shoulders

Question 21

Why might soft tissue sarcomas feel like they are well encapsulated but don’t actually shell out well

Answer 21

This is just pseudoencapsulation due to compression of normal tissue around the tumour

Question 22

What soft tissue sarcomas are much more likely to metastasise

Answer 22

Haemangiosarcoma
Osteosarcoma

Question 23

Management options for soft tissue sarcoma

Answer 23

Radical surgical resection best
PLanned marginal debulking surgery can give good survival times e.g 1 year without recurrence for older dogs

Adding on radiotherapy can increase survival times a lot

Question 24

What grade are most soft tissue sarcomas and is local invasion or metastasis more of an issue

Answer 24

Most are low/intermediate grade
Local invasion more of an issue

Question 25

What breeds are predisposed to melanoma

Answer 25

Terriers Cocker NB: cutaneous melanome normally quite benign

Question 26

How do mast cell tumours present (what layers of skin)

Answer 26

Most are in dermis 15% are in subcutis; must not mistake these for a lipoma

Question 27

General prognosis of cutaneous mast cell tumours

Answer 27

80% cured by simple surgery Later stage disease has much poorer survival time

Question 28

Local and systemic effects of degranulation of mast cell tumours

Answer 28

Locally: get change in tumour size, bruising, wound breakdown Systemically: vomiting/hyporexia, hypotension, oedema, collapse possible

Question 29

When is massive histamine/heparin release from mast cell granules more likely

Answer 29

With large tumours Heavy handling of the mass Self-trauma Mastocytosis

Question 30

Which breeds are more likely to have low risk mast cell tumours vs intermediate risk

Answer 30

Pugs overrepresented; more so low risk Boxers, goldies, labs: intermediate risk Generally younger dogs have better prognosis

Question 31

Out of dermal and subcut mast cell tumours which has a better prognosis

Answer 31

Subcut But don't mistake with a lipoma

Question 32

Poor prongostic indicators of cutaneou s mast cell tumours

Answer 32

ulceration Size >3cm systemic effects High patnaku/kiupel grade Recurrence Rapid growth Lymphadenopathy

Question 33

What are the patnaik vs kiupel grades

Answer 33

Patnail = grades 1, 2, 3; using cell morphology and tissue/stromal involvement Kiupel = high vs low grade just using cell morphology

Question 34

What are some problems with the official staging guide for mast cell tumours

Answer 34

Multiple dermal tumours called a stage 3 but actually these are generally de novo tumours NOT metastases so not that useful e/g in pugs often have multiple tumours but not poor prognosis

Question 35

What does staging of mast cell tumours involve

Answer 35

Sentinel/regional LN aspiration ABdo ultrasound Liver/spleen FNA (could do thoracic xray but not that useful)

Question 36

Is mitotic count in mast cell tumours useful

Answer 36

Yes; correlates with grade. metastasis and survival > or = 2 = high risk

Question 37

Treatment for mast cell tumours; medical and surgical

Answer 37

Medical: antihistamine H1 blocker CHLORPHENAMINE Gastric protectants e.g omeprazole, H2 blockers Surgical removal with proportionate lateral margin and 1 fascial deep planeH

Question 38

How to do a proportionate margin for mast cell tumour removal

Answer 38

Take diameter of mass as circumferential margin from centre out But must have minimum margin 0.5cm and maximum 2cm + one deep fascial plane This gives a very low recurence rate

Question 39

How can we downsize a bulky mast cell tumour before srugery

Answer 39

Use prednisolone for 10 days +/- chlorphenamine

Question 40

Why might we do a planned marginal resection of mast cell tumours

Answer 40

If the lateral margings needed would need radical surgery e.g in lower limb would require amputation Or Where can't get deep plane Then send to hsitopath and wait - If low grade probably won't recur - If high grade can follow up with radioation or revision surgeryW

Question 41

What adjuvant therapies might be used in mast cell management

Answer 41

Want local control with surgery + can add in vinblastine/prednisolone Lomustine is cheaper but risk of liver damage/myelosuppression Chlorambucil/prednisolone cheaper alternative to euthanasia Coudl try tyrosine kinase inhibitors

Question 42

What are tyrosine kinase inhibitors and how might they be useful in mast cell mtumours management

Answer 42

= cytostatic drugs Work because KIT often activated on mast cell causing survival, proliferation, migration Masitinib Toceranib Can be used in face of metastatic disease or where NB: expensive and toxicity risk; GI/haematological/hepatic/renal + slow onset anaemia/thrombocytoaeia

Question 43

What is stelfonta

Answer 43

Tigilanol tiglate = novel intra-tumour therapeutic agent Licensed for non-metastatic cutaneous/subcut MCT below elbow (since inoperable there) Leaves skin deficit which heals by second intention

Question 44

How common are mast cell tumours incats

Answer 44

Not very KIT mutations in most; could use tyrosine kinase inhibitors off label

Question 45

Forms of mast cell tumours in cats

Answer 45

Cutaneous; solitary dermal plaques or masses mostly on head/ears; pruritis Often benign , esp siamese May be atypical histiocytic in which case they spontaneously regress Non-cutaneous form: weight loss, vomiting, abdo mass = poor prognosis

Question 46

Is grading useful in feline cutaneous mast cell tumour

Answer 46

No

Question 47

What age dogs are cutaneous histiocytomas seen in

Answer 47

young

Question 48

WHen is clinical staging of tumours indicated

Answer 48

Only if pretty certain it is malignant