Equine Skin Tumors Flashcards
(82 cards)
1
Q
Take home messages for skin tumors in horses
A
- No one shot cure for cancer
- Pick your battles - not every tumor needs to be treated
- SKin tumors in horses are different than small animal and human
- Don’t make a situation worse (wide margins may not be indicated in areas with limited skin; widen margins with adjunct therapy)
2
Q
How are skin tumors in horses different than in people?
A
- Very slow to metastasize
- Unusual for a horse to die of cancer
3
Q
If you are going to biopsy a tumor in a horse, what should you be ready to do?
A
- Be ready to treat
- Often do excisional biopsies in horses
4
Q
Keys to success with skin tumors
A
- Be more aggressive than the tumor
- Be more stubborn/persistent than the tumor
- Make sure owners are committed to the fight before you start
- Have multiple tools in your toolbox
5
Q
What % of skin tumors of all equine neoplasms?
A
- 50%
6
Q
What is the most common skin tumor?
A
- Sarcoid
7
Q
When are most sarcoids diagnosed?
A
- at necropsy
8
Q
Are most sarcoids impactful on the horse?
A
- No, they are often incidental findings
9
Q
Cell origin for sarcoids
A
- Fibroblastic tumors
- If it’s a fibrosarcoma diagnosis or nerve sheath tumor, he will treat it like a sarcoid
10
Q
Invasiveness and metastatic potential of sarcoids
A
- Locally invasive
- Non -metastatic
- Often benign and considered incidental finding
11
Q
What’s the biggest problem with sarcoids?
A
- May disrupt eyelid functio nor indirectly damage the eye
- May be in locations on the body that inhibit normal use or function
12
Q
Age of horses with sarcoids
A
- Horses 3-6 years of age
- 70% less than 4 years
- Diagnosed in yearlings**
- Risk drops off after 15 years
13
Q
Breeds of horses with sarcoids
A
- Quarter Horses, APpaloosas, Arabians
14
Q
Heritability of sarcoids
A
- Increased incidence in certain families, and a genetic link with specific major histocompatibility complex genes has been demonstrated
15
Q
Bovine papillomavirus and sarcoids
A
- No intact viral particles have been demonstrated in sarcoids so far, DNA, RNA, and proteins of the virus can be found
- Detected in both normal skin and tumors
- Detected in peripheral blood mononuclear cells of sarcoid bearing horses
- Aggressive tumors have a higher viral load
16
Q
Transmission of bovine papillomavirus to horses
A
- Unknown
- Direct or indirect?
- In donkeys it is known that animals having close contact with affected animals are at a higher risk for development of sarcoids
17
Q
Flies and BPV and sarcoids
A
- Flies or other insects may play an important role as a mechanical vector in BPV infection of the horse
- presence of BPV-1 and 2 in Musca autumnalis face flies infestning sarcoid affected horses
18
Q
What are the 6 different types of sarcoid?
A
- Occult
- Verrucose
- Nodular
- Fibroblastic
- Mixed
- Malevolent
19
Q
What is the most benign type of sarcoid?
A
- Occult sarcoid
20
Q
What can happen if you biopsy a sarcoid?
A
- It can come back more aggressive
21
Q
Occult sarcoid locations
A
- Around mouth, eyes, neck or other hairless areas
22
Q
Appearance of occult sarcoids
A
- Areas with mild hyperkeratosis, slightly thickened skin +/- color change
- Can occasionally be mistaken for ringworm or even rub marks from tack
23
Q
Occult sarcoids - can they ever change?
A
- Yes, they may convert
- They may also be worsened by biopsy
24
Q
What is the most common type of sarcoid?
A
- Verrucose or warty sarcoid
25
Location for verrucose or warty sarcoid?
- Face, body, and groin/sheath areas
26
Appearance of verrucose or warty sarcoid?
- Rough, hyperkertatotic appearance and scaling
| - Sessile (flatbased) or pedunculated
27
Growth of verrucose or warty sarcoid
- Often slow growing and not very aggressive until injured or insulted
- Change to fibroblastic sarcoid
28
WHere do nodular sarcoids occur?
- Groin, sheath, or eyelid areas
29
Appearance of nodular sarcoid
- Firm, well-defined subcutaneous, spherical nodules
- Nodules usually lie under apparently normal skin and may be freely movable
- May have dermal and deep attachments
30
Treatment for nodular sarcoids
- He likes to make an incision, take them out, and then close the incision over the top
31
Fibroblastic sarcoid - where do they occur?
- Groin, eyelid, lower limbs and wounds
| - Sites of other types of sarcoid subjected to trauma or insult
32
Appearance of fibroblastic sarcoid
- Characteristic fleshy appearance
| - Pedunuclated and extensive
33
Appearance of fibroblastic sarcoid
- Looks like proud flesh
| - sessile tumors with ulceration
34
How can you differentiate exuberant granulation tissue (proud flesh) from sarcoids?-
Anywhere above the hock or knees you should think sarcoids
35
Mixed sarcoids
- Progressive/transient state between the occult/verrucous types and fibroblastic/nodular types
36
Where do malevolent sarcoids appear?
- Jaw, face, elbow, and medial thigh areas
| - History of repeated trauma to other types of sarcoid (e.g. surgical
37
Aggressiveness and metastasis of malevolent sarcoids
- VERY aggressive, spread rapidly
- Infiltrate in lymphatic vessels resulting in multiple in multiple nodular or fibroblastic masses along these vessels
- Local lymph nodes might also be involved
38
What should you do if you have a non-healing wound anywhere not responding to treatment?
- Biopsy the skin margins
| - Could be SCC or sarcoids
39
Management of Tumors
- Surgical excision
- Laser ablation
- Cryotherapy
- Hyperthermia
- Chemotherapy
- Topical cytotoxic drugs
- Electrochemotherapy
- Immunologic methods
- He usually likes to see every 2-3 weeks for it to start healing but not too much
- He gets rid of anything abnormal
40
Type of margins for tumors
- Reasonable but not excessive
| - If the skin moves above it, he leaves it in
41
What can be a side effect of cryotherapy?
- Turns the skin white
42
What is the drug of choice for electrochemotherapy/chemotherapy?
- Cisplatin
| - Can enhance its uptake with electrochemotherapy
43
What can happen if you have multiple sarcoids related to a virus and you take care of one?
- The rest can fall off
| - In 10% of the cases
44
What is the second most common tumor in horses?
- Squamous cell carcinoma
- 20-25% of equine skin tumors
- Most common tumor of the equine eye and ocular adnexa as well as external genitalia
45
Age of horses with squamous cell carcinoma
- 11-19 years
46
Metastasis with SCC
- As high as 20%
- 10% of horses with ocular tumors have a second mass at a different site
- SLow but steady
47
Where on the body do SCCs tend to occur (external forms) ?
- White, light colored skin
- Eye, conjunctiva, ocular adnexal structures
- Penis, vulva, eyes, lips
48
Where in the body do SCCs tend to occur (internal forms)?
- Stomach, esophagus
- nasal passages, pharynx, larynx
- Perianal tissue
- Lungs
49
Risk factors for SCC
- Sun damaged skin (high altitude)
- Light pigmented skin (white, grey, cremello)
- Breed (Draft, Appaloosa, Paint)
- Persistent phimosis, smegma, trauma to the external genitalia
- maybe papilloma virus?
50
What to do for treatment of TEL SCC?
- Surgical excision of the TEL
- Follow up and remove it all
- Subpalpebral lavage and treat with mitomycin C for one course of treatment
51
Penile SCC treatment options
- He often starts off with treatment of 5-FU
- Drug will stick around long enough in the penis
- May be more aggressive in young horses
- Surgical amputation of the penis can be treatment of choice
- You can amputate or remove the whole penis and PU
- Chemo and laser therapy don't work very well
- Radiation therapy if he could, but it would be like 15-18 anesthesias
52
Melanocytic tumor cell origin
- Melanocytes, dendritic cells of neuroectodermal origin, or melanoblasts
53
% of skin tumors for melanocytic tumors
- 3.8-15% of all skin tumors
54
Which horses get melanocytic tumors?
- Grey horses
- Other horses too of any age or color, but then they tend to be worse prognosis
- Arabians, Percherons, Thoroughbreds
55
% of older grey horses that develop melanocytic tumors? % of those that are NOT malignant?
- 80%
| - 2/3 are not malignant
56
Location of melanocytic tumors?
- Undersurface of tail near the base
- Perineal and perianal regions
- Genitalia
- Mammary gland
- Base of the pinna
- Commissures of the lips
- SKin around the eye
- Parotid salivary gland
57
Treatment for melanocytic tumors - can you remove them?
- He's removed a lot
- They don't come back
- Might grow near that area
- If there in an area where they might eventually become a problem, do an excisional biopsy when they're little
- Don't have to do wide margins, but it can help
58
Melanocytic nevus appearance and description
- Benign tumors that appear as a single, discrete solitary mass and affects younger horses of all coat colors
59
WHo gets melanocytic nevus?
- Younger horses of all coat colors
| - Most horses were 6 years old or younger
60
Location of melanocytic nevus tumors?
- Atypical areas such as the umbilicus, forelimb, rump, shoulder, thigh, neck, and cannon bone
61
Treatment for melanocytic nevus?
- Surgical removal usually curative
62
Dermal melanoma description
- Discrete, solitary masses (1-2 tumors) in older gray horses
63
Mean age with dermal melanoma
- 13 years
64
Dermal melanoma behavior
- Most tumors are benign
65
Location of dermal melanomas
- "Typical sites"?
| - Commissure?
66
Treatment of dermal melanomas
- Surgical excision of noninvasive tumors usually curative
67
Dermal melanomatosis who gets?
- Horses 15 years or older
68
Metastatic potential of dermal melanomatosis?
- Internal metastasis is likely
69
Treatment and prognosis for dermal melanomatosis?
- Surgical excision is often curative for the masses that are removed, but the remaining masses continue to grow, and new tumors develop
70
Treatment discussion for a tumor around the tail head?
- Shell it out and leave it to heal by second intention
- Palliative treatment
- OFten heal well
- Keep it clean with a fly spray
- Eventually granulate in well and do well eventually
71
Who gets anaplastic malignant melanomas?
- Older horses (usually >20 years) of any hair color
72
Histologic features of anaplastic malignant melanomas?
- Variable pigmentation, extremely pleomorphic epithelioid cells, single cell invasion of the epithelium, and numerous mitotic figures
73
Metastatic potential of anaplastic malignant melanomas
- Uncommon, but metastasize quickly
74
Risk of disease for anaplastic malignant melanomas between gray and non-gray horses
- The same
75
Treatment for anaplastic malignant melanomas
- Not a good treatment
- Autologous vaccines not usually successful
- Oncept (human tyrosine kinase might be helpful in a non-gray horse)
76
mast cell tumors - how common?
- Uncommon
77
Mast cell tumor sex, breed, and age predilection?
- Sex: males 5x more likely than females
- Arabian horses predisposed
- No age predilection
78
Treatment of mast cell tumor
- Surgery or radiation
79
What are the two types of mast cell tumors in horses, and which is most common in horses?
- Two types are hyperplastic type and neoplastic type
| - Most equine mast cell tumors are hyperplastic
80
CLinical presentation of mast cell tumors
- Most common is a single cutaneous nodule, often located on the head
- Surface of the nodules may be normal, hairless, or ulcerated
- Diffuse swelling on a lower extremity, usually below the carpus or hock
- Swelling is firm, and the overlying skin is normal in appearance
81
Radiographs of MCT on lower extremity
- Multifocal areas of soft tissue mineralization
82
Diagnosis of MCT
- Biopsy
