Exam 1 - Equine Skin & Eyelid Neoplasia

Question 1

what are the 3 most common types of skin tumors in horses?

Answer 1

sarcoid

squamous cell carcinoma

melanoma

Question 2

other than the most common types of skin tumors, what are 3 nodular diseases affecting horses?

Answer 2

eosinophilic granulomas - insect related

papilloma

aural plaques

Question 3

what is the number one most common skin tumor in the horse?

Answer 3

the sarcoid

Question 4

what is the suggested pathogenesis of equine sarcoids?

Answer 4

• a bovine papilloma virus or some closely related virus
• some horses appear genetically predisposed
• synergistic exposure to virus & genetic susceptibility

Question 5

what is this lesion?

Answer 5

flat, occult sarcoid - do not biopsy!!!!! you will anger it

Question 6

what are the 6 sarcoid classifications?

Answer 6

nodular

fibroblastic

verrucous

occult

malevolent

mixed

Question 7

what is the only way to diagnose a sarcoid?

Answer 7

skin biopsy

Question 8

what’s the problem with biopsies & certain sarcoid classifications?

Answer 8

flat/occult sarcoid types will be exacerbated by biopsies

Question 9

what is important to remember in sarcoid treatment?

Answer 9

all sarcoids will respond differently to treatment

Question 10

what is your basic treatment plan for sarcoids?

Answer 10

debulking combined with local infusion of chemotherapy - mitomycin C

topical irritants - acyclovir & DMSO

Question 11

what tumor type develops in dark skinned horses?

Answer 11

melanomas

Question 12

T/F: over 80% of flea bitten gray horses develop melanomas as they age

Answer 12

true

Question 13

what are the 3 variants of melanoma biological behavior?

Answer 13

tumor persists for years, grows slowly, & doesn’t metastasize

tumor persists for years, becomes malignant, & metastasizes

tumor grows rapidly & metastasizes quickly

Question 14

what are your treatment options for melanomas?

Answer 14

benign neglect, radical surgical excision, chemo - cisplatin, bleomycin, cryosurgery, & vaccine?

Question 15

what is new with cimetidine in regards to melanoma treatment?

Answer 15

H2 blocker that has been reported to reduce the mass size by greater than 50% in some cases

Question 16

papillomas are most commonly, verrucous warts that occur in horses less than how old?

Answer 16

3 years old

Question 17

how do you treat papillomas?

Answer 17

you don’t really - they are self-limiting with no treatment necessary

autologous vaccine option

Question 18

what is this?

Answer 18

aural plaque

Question 19

what is this?

Answer 19

papillomas

Question 20

what is an aural plaque?

Answer 20

depigmented plaques that coalesce & can become scaly - often irritated by black flies

Question 21

similar lesions to aural plaques can occur at what other locations?

Answer 21

anus & vulva

Question 22

what is the treatment for aural plaques?

Answer 22

there is no treatment required

Question 23

T/F: there is curative treatment for aural plaques

Answer 23

false - there isn’t

Question 24

what is the most common ocular/periocular tumor in the horse?

Answer 24

periocular squamous cell carcinoma

Question 25

periocular squamous cell carcinomas are highly invasive & often lead to what treatment?

Answer 25

enucleation

Question 26

what is your first treatment option you should utilize in a periocular squamous cell carcinoma?

Answer 26

surgical debulking!!! topical/injectable chemotherapy, cryotherapy, & radiation

Question 27

what is this lesion? what is it in humans?

Answer 27

solar elastosis - precancerous lesion in people

Question 28

T/F: solar elastosis is probably a precancerous lesion in horses because of their shorter lifespan turning it into SCC in all cases

Answer 28

true

Question 29

how do you treat solar elastosis?

Answer 29

reduce sun exposure!!!! fly mask with uv protection, shade, night turn out, children's sun screen

Question 30

what is the treatment for 3rd eyelid SCC? adjunctive therapy?

Answer 30

surgical removal with a clean margin - can be curative chemo - cisplatin & 5-fluorouracil cryotherapy

Question 31

if I see this lesion, what are my 2 differentials?

Answer 31

SCC & habronemiasis

Question 32

what can be a potential problem with removing a 3rd eyelid SCC?

Answer 32

potential for scarring can lead to enucleation

Question 33

what is the technique for treatment of 3rd eyelid SCC tumors with photodynamic dye therapy?

Answer 33

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

Question 34

why is it important to continue with photodynamic dye therapy when using it on a SCC 3rd eyelid tumor?

Answer 34

must continue until you get normal tissue - only marker of success

Question 35

T/F: a tumor on the upper eyelid is harder to remove than the lower eyelid

Answer 35

true

Question 36

what is a periocular sarcoid?

Answer 36

fibrous tumor that is extremely locally invasive & hard to resolve with recurrence being common regardless of the treatment protocol

Question 37

what is this?

Answer 37

periocular sarcoid

Question 38

what are some options for treatment of periocular sarcoids?

Answer 38

surgical excision, cryotherapy, radiation, mistletoe extract, & medical treatments (cisplatin, 5-fluorouracil)

Question 39

what is a common treatment used for periocular sarcoid?

Answer 39

mitomycin c & acyclovir

Question 40

what is the relation between photosensitization & SCC?

Answer 40

develops secondary to liver disease!!! or can be caused by toxic plant ingestion

Question 41

what is this lesion?

Answer 41

photosensitization & possible SCC