Dermatology skin tumours and mast cell tumours Flashcards
What are the different types of epithelial tumours
Cutaneous papillomas; can see oral ones in dogs, these regress
Basal cell tumour: common
Squamous cell carcinoma
Characteristics of basal cell tumour
Middle aged animals
Head and neck typically
May be pigmented
Usually benign; cure via surgery
What is the most common pigmented mass on the head of a cat
Basal cell tumour NOT melanoma
Key difference between SCC on the nose vs other parts of body in dogs
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]
KEy difference in aetiology of SCC of nasal planum in dogs vs cats
In cats = related to UV light exposure
In dogs = genetic; see more in retrievers and collies; quite metastatic
What do SCC look like and where do they arise
Arise in lightly pigmented parst of body, assocaited with UV light exposure
Can look like cauliflower lesion or more like a non-healing ulcer
How can we treat superficial SCC of nasal planum in cats
Strontum brachytherapy
Could also try photodynamic therapy
How does SCC of nail bed present
Sore swollen toe; often misdiagnosed as a nail beg infection but antibiotics don’t work
Where might adnexal tumours come from
Sebaceous gland
Hair follicle
Perianal/hepatoid gland adenoma
What must be on our differential list for any epithelial lesion which is ulcerated or erosive
Squamous cell carcinoma
Characteristics of primary cutanoue lymphoma
T cell
PResents as multiple cutaneous nodules/plaqes
Aggressive with widespread disseminatino
Poor prognosis
PResentation of epitheliotrophic lymphoma
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)
Treatment of epitheliotrophic lymphoma
Poor
Don’t respond to chemo
CAn give steroids to help pruritis
Mouth lesions can have radiotherapy and respond well
WHat is a plasmactyoma
Solitary skin tumour with benign behaviour; cure via sugerical excision
What is canine cutaneous histiocytoma
Common benign tumour of young dogs; see rapidly growing lesion on head mostly
Then spontaneous regression related to cytotoxic T lymphocte influx
How does reactive histiocytosis present
Can be skin only
Or systemic
INfiltration with histiocytes/antigen-presenting cells
Lesions wax and wane but slowly proress
What breeds are predisposed to disseminated histiocytic sarcoma and what is the prognosis like
Bernese mountain dogs
Retriever
Rottweiler
Very poor prognosis
BReed predisposition for histiocytic sarcoma
Flat coated retriever
What organism is associated with oesophageal sarcoma
Spirocerca lupi encysting there
Thought to be related to chronic inflammation aetiology
Feline injection site sarcoma characteristics
YOung animals
Very aggressive
High rate of local recurrenace so need huge margins
Must consider whenever we see a cat with mass betewen shoulders
Why might soft tissue sarcomas feel like they are well encapsulated but don’t actually shell out well
This is just pseudoencapsulation due to compression of normal tissue around the tumour
What soft tissue sarcomas are much more likely to metastasise
Haemangiosarcoma
Osteosarcoma
Management options for soft tissue sarcoma
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
What grade are most soft tissue sarcomas and is local invasion or metastasis more of an issue
Most are low/intermediate grade
Local invasion more of an issue
What breeds are predisposed to melanoma
Terriers
Cocker
NB: cutaneous melanome normally quite benign
How do mast cell tumours present (what layers of skin)
Most are in dermis
15% are in subcutis; must not mistake these for a lipoma
General prognosis of cutaneous mast cell tumours
80% cured by simple surgery
Later stage disease has much poorer survival time
Local and systemic effects of degranulation of mast cell tumours
Locally: get change in tumour size, bruising, wound breakdown
Systemically: vomiting/hyporexia, hypotension, oedema, collapse possible
When is massive histamine/heparin release from mast cell granules more likely
With large tumours
Heavy handling of the mass
Self-trauma
Mastocytosis
Which breeds are more likely to have low risk mast cell tumours vs intermediate risk
Pugs overrepresented; more so low risk
Boxers, goldies, labs: intermediate risk
Generally younger dogs have better prognosis
Out of dermal and subcut mast cell tumours which has a better prognosis
Subcut
But don’t mistake with a lipoma
Poor prongostic indicators of cutaneou s mast cell tumours
ulceration
Size >3cm
systemic effects
High patnaku/kiupel grade
Recurrence
Rapid growth
Lymphadenopathy
What are the patnaik vs kiupel grades
Patnail = grades 1, 2, 3; using cell morphology and tissue/stromal involvement
Kiupel = high vs low grade just using cell morphology
What are some problems with the official staging guide for mast cell tumours
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
What does staging of mast cell tumours involve
Sentinel/regional LN aspiration
ABdo ultrasound
Liver/spleen FNA
(could do thoracic xray but not that useful)
Is mitotic count in mast cell tumours useful
Yes; correlates with grade. metastasis and survival
> or = 2 = high risk
Treatment for mast cell tumours; medical and surgical
Medical: antihistamine H1 blocker CHLORPHENAMINE
Gastric protectants e.g omeprazole, H2 blockers
Surgical removal with proportionate lateral margin and 1 fascial deep planeH
How to do a proportionate margin for mast cell tumour removal
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
How can we downsize a bulky mast cell tumour before srugery
Use prednisolone for 10 days +/- chlorphenamine
Why might we do a planned marginal resection of mast cell tumours
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
What adjuvant therapies might be used in mast cell management
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
What are tyrosine kinase inhibitors and how might they be useful in mast cell mtumours management
= 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
What is stelfonta
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
How common are mast cell tumours incats
Not very
KIT mutations in most; could use tyrosine kinase inhibitors off label
Forms of mast cell tumours in cats
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
Is grading useful in feline cutaneous mast cell tumour
No
What age dogs are cutaneous histiocytomas seen in
young
WHen is clinical staging of tumours indicated
Only if pretty certain it is malignant
