Skin Flashcards
Which of the following statements regarding skin tumors are the most accurate?
A) Merkel cell tumors are highly aggressive in the canine patient, with high rates of metastasis
B) Local invasion of apocrine gland carcinomas is very common, with more than half demonstrating invasion of the stroma
C) Trichoepitheliomas are always benign and does not invade surrounding tissues
D) Malignant pilomatricoma has not been reported in dogs
B)
Merkel is malignant in humans but usually benign in dogs. There is a malignant trichoepithelioma. Malignant pilomatricoma is rare in dogs, never reported in cats
What are the most common skin tumours in the dog?
mast cell tumour, lipoma, histiocytoma
What are the most common skin tumours in the cat?
basal cell tumour, mast cell tumours, SCC
What’s the proposed staging system for primary tumours of the ear canal?
T1 = tumour confined to the external or horizontal canal
T2 = tumour extending beyond the tympanic membrane
T3 = tumour extending beyond the middle ear/ bone destruction
What are some prognostic factors for tumours of the ear canal?
What are the three most prevalent skin tumors in cats (in order):
a. Squamous Cell Carcinoma, Basal Cell Tumor, Mast Cell Tumor
b. Basal Cell Tumor, Mast Cell Tumor, Fibrosarcoma
c. Mast Cell Tumor, Squamous Cell Carcinoma, Basal Cell Tumor
d. Basal Cell Tumor, Mast Cell Tumor, Squamous Cell Carcinoma
D
In people, basal cell carcinomas (BCCs) are thought to arise from critical mutations in the hedgehog signaling pathway. In the dog, which of the following is involved in the transcription of the canine hedgehog signaling cascade?
a. Chromosome 10 of gene GLI1
b. p53
c. p27
d. Beta-Catenin
A
You have a 7 yo MC Norweigan Elkhound that presented with several dermal masses along the neck, back, shoulders, and tail. Since there were multiple masses, surgical excision of all masses would not be feasible. As such, you elected treatment with Isotretinoin. Which of the following benign dermal masses does this dog most likely have?
a. Trichoblastoma
b. Trichoepithelioma
c. Infundibular Keratinizing Acanthoma
d. Pilomatricoma
e. Nodular Dermatofibrosis
C
Which of the following correctly ranks the following skin tumors of dogs from most to least common:
A. Lipoma, papilloma, melanoma, SCC
B. Basal cell tumor, histiocytoma, fibrosarcoma, lipoma
C. MCT, melanoma, histiocytoma, sebaceous adenocarcinoma
D. MCT, lipoma, histiocytoma, perianal gland adenoma
D
What’s a risk factor for SCC?
UV radiation, especially in light-colored cats
How does papillomavirus induce neoplastic transformation?
- can only effect terminally differentiated cells –> stimulate increased proliferation and differentiation of keratinocyte once infected
- destabilizes p53 by viral protein E6 and inhibition of pRB by viral protein E7
- disruption of p53 increases p16 protein level –> can be detected by IHC
What cancer can papillomavirus predispose dogs to?
squamous cell carcinoma
What is papillomavirus associated with in cats?
viral plaques and feline fibropapilloma (feline sarcoids)
- can progress to squamous cell carcinoma
- up to 70% of “UV Protected” SCC are positive for PPV
What does positive staining of p27 mean?
p27 is a protein important in maintaining cells in G0 – a decrease = more cell cycle
What’s the importance of Beta-catenin?
Beta catenin is responsible for normal skin homeostasis
nuclear presence of this protein = pathway activation
- aberrantly activated in formation of hair follicle tumours
What’s the role of cyclin A in SCC?
Cyclin A was present in 90% of feline SCC, 40% of canine SCC
T or F. Digit and oral melanoma are highly malignant tumours?
True
What kind of cells can be found in cytology of basal cell carcinoma?
inflammatory cells, squamous cells, sebaceous epithelial cells, melanin, and melanophages
Which dog breeds are predisposed to basal cell tumour?
Cocker Spaniel and Poodle
(although overall rare in dgos)
How does basal cell tumour look like in the dog?
plaques or nodules in the skin; alopecic, intact or ulcerated
Median age = 9y
How aggressive in basal cell tumour in the dog?
low grade malignancy
recurrence possible
no metastasis reported
How frequent is basal cell tumour in the cat?
now thought to be rare – mostly reclassified to solid-cystic apocrine ductular adenoma (60%) or trichoblastomas (40%)
- 10-20% of feline skin tumours
Where are feline basal cell tumour mostly located?
head and neck
can look like melanoma
How aggressive is basal cell tumour in the cat?
mostly benign, but malignant ones have been described thought metastatic rate appears low
What’s the treatment for basal cell tumour?
wide surgical excision = good long-term control - aim for 5-10mm
How frequent is papilloma in the dog and cat?
rare
What’s the typical signalment for canine cutaneous papilloma?
young (3.2y)
lesion can spontaneous regress
surgical excision = usually curative
What’s the behaviour of papilloma in the cat?
Cats have fibropapilloma
- proliferation of mesenchymal cells covered by hyperplastic epithelium
- more similar to equine sarcoid
What is squamous cell carcinoma in situ?
A squamous cell carcinoma that has not broke through the basement membrane
What’s a Bowen’s carcinoma?
when SCC in situ appears in multiple sites
primarily seen in cats
- can be anywhere on the body – haired or non-haired, with or without UV exposure
- solitary = unusual
What’s actinic keratosis?
SCC in situ that’s due to UV exposure
- mostly on the head, or lightly haired skin with UV exposure
- often solitary
- solar elastosis and fibrosis of the skin
What’s the treatment for SCC in situ?
Surgery
- cats with single nasal and pinna lesion – DFI = 594d, MST = 675d
Strontium 90
- 100% CR (n=14), no recurrences, MST >3000days
- metastasis = rare
What’s the treatment for Bowen’s carcinoma?
since it’s usually multifocal, marginal surgery is indicated for palliation when other therapy is no longer effective
- imiquimod cream for cats
- photodynamic therapy
What’s the signalment for squamous cell carcinoma in the cat?
- > 10y
- predilection on heads, esp lightly haired, white cats
- Siamese, Himalayan, and Persians
Which dog breeds are predisposed to squamous cell carcioma?
Goldens and Lab for nasal planum SCC
Bloodhounds, basset hounds and standard poodles for cutaneous SCC
What paraneoplastic syndrome has been reported with cutaneous SCC?
hypercalcemia in cats
Where can the SCC metastasize to in cats?
regional lymph nodes and lungs @ time of death
Can cutaneous SCC metastasize in dogs?
rare
Nasal planum ones can go to the mandibular lymph nodes
What’s the treatment for cutaneous SCC?
wide surgical excision – DFI 594days (cats)
What’s the role of chemotherapy in cutaneous SCC in dogs and cats?
- Carboplatin compouded in sterile sesame seed oil - intratumoral administration nasal planum SCC in cats - CR 73%, 55% PFS @ 1y
- Electrochemotherapy with bleomycin for cutaneous SCC in cats – 82% CR for 2m to 3y
- Dogs – metastatic SCC - cisplatin
What’s infundibular keratinizing acanthoma?
This is a benign tumour
common in the dog (esp Nordic breeds), rare in the cat
What’s the most common place IKA?
- back, neck, trunk, tail, and upper limbs
- solitary or multiple lesions
- may have a central core that communicates with the surface
What’s the most common malignant tumour of the ear canal?
ceruminous gland adenocarcinoma
- has metastatic potential
What’s the prognosis for malignant ear canal tumours treated with TECA-LBO?
cats: 42-50.3m
dogs: not reached @ 36m
What’s the prognosis for malignant ear canal tumours treated with RT?
PFS: 39.5m
1year PFS @ 56%
What are some prognostic factors for primary tumours of the ear canal?
What’s the proposed staging scheme for primary tumours of the ear canal?
What are the most common malignant digital tumours in the dog?
SCC (47%), melanoma (24%), STS (13%), MCT (8%), OSA (3%)
What’s the common signalment of canine digital SCC?
- about 3% of dogs with digital SCC has involvement of multiple digits
- large black dogs
- front limbs > hind limbs
What’s the disagreement rate in digital tumour diagnosis?
20%, with 75% of disagreement being clinically significant
What’s the most common digital tumours in the cat?
SCC (25%), fibrosarcoma (23%), adenocarcinoma (22%), OSA (8%), HSA (8%), MCT (7%)
Which tumour type can have multiple digit involvement?
fibrosarcoma, adenocarcinoma, SCC
What’s acrometastasis?
lung-digit syndrome
majority of cats with digital SCC have primary lung tumour
- can be differentiated based on histo and cell morphology
What;s the MST for acrometastasis vs primary digital SCC?
4.9 weeks vs 29.5 weeks
What’s a prognostic factor for digital melanoma in the dog?
bone involvement
What’s the % of bone involvement in canine digital SCC and melanoma?
SCC: 80%
melanoma: 5-100%
What’s the metastatic rate of canine digital SCC?
on presentation: 6-16%
additional 9-17% can develop metastasis later on
What’s the metastatic rate of canine digital melaoma?
on presentation: 32-40% (either regional LN or Lung)
additional 10-26% will develop it after definitive therapy
What’s the typical findings for feline primary digital SCC?
- 4/8 have bone involvement
- 1/8 regional LN involvement
- none had lung mets
What’s the typical findings for feline primary digital melanoma?
- 4/5 met to regional lymph node, lungs, bone and/or vertebrae
What’s the recommended treatment for digital tumours?
digital or partial food amputation
What’s the prognosis for digital SCC treated with surgery alone?
1 yr survival 50-83%
2 yr survival 18-62%
Is subungal location worse for dogs with digital SCC?
No, they tend to do better
1y survival 95%
2y survival 74%
What’s the MST for digital SCC in cats?
73days to 29.5 weeks
What’s the prognosis for canine digital melanoma treated with surgery alone?
1 yr survival = 42-57%
2 yr survival = 13-36%
- Brockley et al 2013 paper found MST = 1350d with carboplatin (thought not sign between w/ or w/out carbo)
What’s the MST for cats with digital melanoma?
0 to >577 days
metastatic disease possible
