Exam 1 - Equine Skin & Eyelid Neoplasia Flashcards
what are the 3 most common types of skin tumors in horses?
sarcoid
squamous cell carcinoma
melanoma
other than the most common types of skin tumors, what are 3 nodular diseases affecting horses?
eosinophilic granulomas - insect related
papilloma
aural plaques
what is the number one most common skin tumor in the horse?
the sarcoid
what is the suggested pathogenesis of equine sarcoids?
- a bovine papilloma virus or some closely related virus
- some horses appear genetically predisposed
- synergistic exposure to virus & genetic susceptibility
what is this lesion?
flat, occult sarcoid - do not biopsy!!!!! you will anger it
what are the 6 sarcoid classifications?
nodular
fibroblastic
verrucous
occult
malevolent
mixed
what is the only way to diagnose a sarcoid?
skin biopsy
what’s the problem with biopsies & certain sarcoid classifications?
flat/occult sarcoid types will be exacerbated by biopsies
what is important to remember in sarcoid treatment?
all sarcoids will respond differently to treatment
what is your basic treatment plan for sarcoids?
debulking combined with local infusion of chemotherapy - mitomycin C
topical irritants - acyclovir & DMSO
what tumor type develops in dark skinned horses?
melanomas
T/F: over 80% of flea bitten gray horses develop melanomas as they age
true
what are the 3 variants of melanoma biological behavior?
tumor persists for years, grows slowly, & doesn’t metastasize
tumor persists for years, becomes malignant, & metastasizes
tumor grows rapidly & metastasizes quickly
what are your treatment options for melanomas?
benign neglect, radical surgical excision, chemo - cisplatin, bleomycin, cryosurgery, & vaccine?
what is new with cimetidine in regards to melanoma treatment?
H2 blocker that has been reported to reduce the mass size by greater than 50% in some cases
papillomas are most commonly, verrucous warts that occur in horses less than how old?
3 years old
how do you treat papillomas?
you don’t really - they are self-limiting with no treatment necessary
autologous vaccine option
what is this?
aural plaque
what is this?
papillomas
what is an aural plaque?
depigmented plaques that coalesce & can become scaly - often irritated by black flies
similar lesions to aural plaques can occur at what other locations?
anus & vulva
what is the treatment for aural plaques?
there is no treatment required
T/F: there is curative treatment for aural plaques
false - there isn’t
what is the most common ocular/periocular tumor in the horse?
periocular squamous cell carcinoma
periocular squamous cell carcinomas are highly invasive & often lead to what treatment?
enucleation
what is your first treatment option you should utilize in a periocular squamous cell carcinoma?
surgical debulking!!! topical/injectable chemotherapy, cryotherapy, & radiation
what is this lesion? what is it in humans?
solar elastosis - precancerous lesion in people
T/F: solar elastosis is probably a precancerous lesion in horses because of their shorter lifespan turning it into SCC in all cases
true
how do you treat solar elastosis?
reduce sun exposure!!!! fly mask with uv protection, shade, night turn out, children’s sun screen
what is the treatment for 3rd eyelid SCC? adjunctive therapy?
surgical removal with a clean margin - can be curative
chemo - cisplatin & 5-fluorouracil
cryotherapy
if I see this lesion, what are my 2 differentials?
SCC & habronemiasis
what can be a potential problem with removing a 3rd eyelid SCC?
potential for scarring can lead to enucleation
what is the technique for treatment of 3rd eyelid SCC tumors with photodynamic dye therapy?
tumor is debulked down to the surface level - clean margins are not the goal!!!
tumor bed is injected with verteporfin & a light source/laser is used to activate the dye
chloramphenicol ophthalmic ointment is applied topically after
flunixin meglumine is used for pain control/swelling post-op for 2-5 days
why is it important to continue with photodynamic dye therapy when using it on a SCC 3rd eyelid tumor?
must continue until you get normal tissue - only marker of success
T/F: a tumor on the upper eyelid is harder to remove than the lower eyelid
true
what is a periocular sarcoid?
fibrous tumor that is extremely locally invasive & hard to resolve with recurrence being common regardless of the treatment protocol
what is this?
periocular sarcoid
what are some options for treatment of periocular sarcoids?
surgical excision, cryotherapy, radiation, mistletoe extract, & medical treatments (cisplatin, 5-fluorouracil)
what is a common treatment used for periocular sarcoid?
mitomycin c & acyclovir
what is the relation between photosensitization & SCC?
develops secondary to liver disease!!!
or can be caused by toxic plant ingestion
what is this lesion?
photosensitization & possible SCC
