Equine Neoplasia & chemotherapy Flashcards
Describe what sarcoids are?
Fibroblastic transformation of equine dermis
- Locally invasive
- Non-ùetastatic
- rarely regress spontaneously
What aetiology of sarcoids?
Association with BPV 1 & 2
- BPV DNa and viral oncogenes can be detected in sarcoid tissues
- harder ot induce dx with BPV
Who are affected by sarcoids?
2-8% of horses - all members of equid family worldwide
Disease severity associated with?
- Viral load
- Individual immune response
What are the 6 different types of sarcoids?
- Occult
- Verrucose
- Nodular
- Fibroblastic
- Mixed
- Malevolent
Describe occult sarcoids?
- Represent earliest form of
the disease. - Can remain stable for many
years. - Usually appear as a roughly
circular hairless area or
altered hair quality. - DDx: Ringworm
Describe verrucose sarcoid?
- Grey, scaly or warty
appearance. - Frequently coalesce into
larger lesions. - DDx: Ringworm or rubs
Describe Nodular sarcoids?
- Easiest to see and identify.
- Discrete firm nodules under
the skin. - Categorised on whether
adherent to overlying skin or
bound to deeper structures.
Describe Fibroblastic sarcoids?
- Fleshy and aggressive
appearance. - Ulcerative.
- Quick to grow.
- Often pedunculated.
Described mixed sarcoids?
- Very common presentation.
- Often verrucose that develop
nodular component.
what common locations of sarcoids?
- Head and Neck (around eyes, ears and lips)
- Extremities
- Axilla
- Ventral abdomen
- Inguinal region
Where do they usually arise?
areas of previous skin trauma ddx:proud flesh but also spontaneous
What tx options for sarcoids?
- surgical
- Immune modulation
- Chemo
Radiotherapy - Cryotherapy
Describe surgical tx?
o Ligation (‘banding’)
o Sharp resection
o Laser surgery
o SMART surgery
o (combination therapy)
Describe immune modulation?
o Topical (Imiquimod)
o Intralesional (BCG: Mycobacterium
cell wall fraction)
Describe chemo?
o Topical (5-FU, AW4-LUDES,)
o Intralesional (5-FU, cisplatin)
Make a table of pros and cons for tx options of sarcoids?
ligation sx?
cheap and easy
sharp resection?
- Wide mrgins rq (9-16mm reported to be sufficient)
- Recurrence common w/in 6 months
SMART surgery?
one cut one blade
Electrosurgery?
high success rate when performed under GA with 12mm margins
Laser surgery?
(diode or Carbon laser)
o 60-80% success rate reported (Diode better than CO2).
o Recurrence common particularly with verrucous sarcoids.
o Often favoured over sharp resection.
o Wound heals by secondary intention- prolonged healing
What is used in immunotherapy against sarcoids?
Imiquimod - >immune modifier - amplifies local immune response
How good is Imiquimod?
Good responses reported
60% resolution
80% reduction in size
Side effects of immunotherapy?
minimal -> alopecia, erythema, depigmentation
How to admin imiquimod?
Long course therapy
- Applied 2-3 x weekly for 4-6 months
- Can be applied by owner (PPE!)
Describe AW5 Ludes Cream?
“liverpool cream”
- Heavy metals
- 5-fluorouracil & thiouracil
How does it work (AW5Ludes)?
caustic - causes cell necrosis of sarcoid
Considerations of Ludes cream?
- Varying strengths - 3-5 days
- Not licensed, compounded product
- Only available through Equine Medical solutions and cannot be dispensed to owners
Describe the use fo 5-Fluorouracil (5-FU) 5% topical cream?
- Anti-metabolite (inhibits DNa replication with limited effect on normal skin
- Only penetrates to depth approx 2mm -> superficial lesions (Verrucose or occult sarcoids)
How to apply/ use 5-Fluorouracil?
Daily application for 3-4 weeks
- Variable success
- Safe for owners to use with precautions
-> Carcinogenic an dmutagenic -> gloves, lesion dressings & biological disposal
T/F there is an injectable formulation of 5-FU for intra-lesional admin?
TRUE
Describe Cisplatin use for intralesional chemo?
- Heavy metal comoiunds which inhibits DNa synthesis
- Used to treat small solid tumours or act as adjunct following debulking
What two approaches for use fo cisplatin?
- 1 ml of an aqueous solution of 10 mg cisplatin/ml and 2 ml sesame oil, used
at a dose rate of 1 mg cisplatin/cm3 of tumour. 4 injections at 2 wk intervals. - Cisplatin impregnated beads, implanted in each 1cm3 of tissue. 2
applications, 1 month interval.
How is intralesional chemo done?
- Under GA
- Careful with human health
what side effects of cisplatin impregnated beads?
alopecia, swelling, scarring
-> BUT improved safety profile to intra-lesional injection
Describe Cisplatin Electrochemotherapy
- Utilises electrical field pulses to increase cell membrane permeability
(electroporation). - Increases cisplatin delivery to tumour.
- Requires GA.
- No. of treatment depends on size, location and depth of infiltration
What is intra-lesional tx with mycobacterium cell wall fraction immunostimulant ?
BCG - attenuated strain of M.bovis
- Stimulates local cell mediated immune response
- Hard to obtain
What product / How to admin for Mycobacterium cell wall intra-lesional tx?
- Immunocidin
- Special import license
- Injected at 2 week intervals repeated as required
Success with mycobact tx?
reasonable 52.9% complete resolution
-> good for peri-ocular sarcoids where laser or topical nto an option
Describe raidotherapy?
Brachytherapy with gamma radiation -> Gold standard?
Describe low and high dose RadioT?
Low dose-> iridium wires implanted into tissues for 2-3 weeks
High dose - gamma radiation source delivered in pulses within single treatment period
High success rates with or without debulking
Limitations of radiotherapy?
- Very expensive
- Limited availability
- Major safety restrictions
- May require long tiem to see effect
What else can be used for Radiotherapy?
=> STRONIUM PLESIOTHERAPY
- Locally applied
- Superficial form of radiotherapy
- Limited penetration
- Only suitable for small, superficial lesions
Benefits of strontium?
- isolation not required
- Performed under standing sedation
- Cost effective
Cryotherapy ?
- Appplication of liquid nitrogen/ C2 to destroy tumor cells
- 3 freeze thaw cycles, bringing sarcoid tissues to -20 to -30°C
=> induces cell rupture
=> include margin of normal skin
When is cryotherapy helpful?
- For occult or verrucose sarcoids
- combo therapy to treat tissue following surgical/ laser resection
Describe SCC in horses
- Primary SCC is the 2nd most common equine tumours
- Metastases common
- Restricted to squamous epithelium -> proliferative form, uclerative form
What locations most commonly seen?
- Periorbital and genital SCC
- Mucous and muco-cutaenous junctions
What risk factors to SCC?
- UV light exposure -> non pigmented skin
- Also Equine papillomavirus-2
- Genetics
Describe Periorbital SCC?
- Mean age 13 yrs
- Account for 72% of mucocutaenous SCC
- Inc prevalence in Paint, quarterhorses, Apaloosas & draught
- Most arise from conjunctiva or cornea
- Raised, pink white mass with irregular surface
Describe Genital SCC ?
Mean age 19-21yrs
- Genital forms in younger animals tend ot have higher rate of malignancy
- Evidence that there may be an association with Equine Papillomavirus
- Very rare to see ins tallions vs geldings
SCC diagnosis?
- Based on clinical presentation
- Biopsy required for definitive diagnose (often exisional)
DDX for SCC?
- Sarcoid
- Papilloma
- Proud flesh
- Melanoma
Tx options for SCC?
- Radiation (Gold standard in suitable sites)
- Surgical excision with wide margins.
- High recurrence rate.
- Cryosurgery
- Topical/intralesional chemotherapy
- 5FU/Cisplatin/Mitomycin-C
How to treat 3rd eyelid lesions?
Surgical excision (resect entire nictitating membrane).
How to treat palpebral lesions?
Palpebral lesions – Surgical excision + Cryotherapy/radiotherapy.
How to treat corneal lesions?
Lamellar keratectomy + chemotherapy after cornea healed.
– Mitomycin C solution.
Hwo to treat genital form SCC?
- Surgical resection + adjunctive therapy (cryotherapy). => En-bloc resection of glans penis.
- Prolonged topical treatment with 5-fluoruracil.=> Early intervention better – treat when small
SCC prognosis depends on what?
- The site of the lesion and its suitability for any effective therapy
- The malignancy of the tumour itself
- The duration of the lesion and failed attempts to treat it
- The extent of secondary consequences arising from the tumour.
T/F SCC in horses tend to be more malignant than in other species?
False - less!
T/F Gastric carcinoma, oropharyngeal carcinoma and penile carcinoma in younger geldings usually more malignant than others
true
What three different melanomas can we come across?
Detail dermal melanoma?
- Affects older grey horses almost exclusively. (Approx 80% prevalence in aged populations)
- Single (DM), multiple or coalescent cutaneous spherical
nodules. - Most prevalent in perineal skin. (Can also develop in parotid LN and salivary glands.)
How does melanoam behave?
- SLOW growth
- Can reach considerable size
- Ulceration is common
Tx for melanoma?
Limited for large lesions - surgical resection early otherwise close monitoring
tx for isolated lesions?
Can be treated as soft tissue neoplasm =>
- Surgical excision +/- adjunctive chemo
- Intralesional chemo (cisplatin beads)
What si the Melanoma Vaccine?
- Limited evidence to support the use at thsi time but anecdotal evidence promising
- Combine with surgical resection
Prognosis for melanoma?
- Good if uncomplicated and not inconvenient site
- Unpredictabel progression
Noeplasia in donkeys?
MSOT common is sarcoid
How common is use of systemci chemo in equine therapy?
- RARE
- Lymphoma most common to use for
- usually prednisolone palliatively 1-2mg PO SID
