Tumor Specific 25% AB Flashcards
Skin/Sq, STS, FISS, GI, endocrine
What percentage of cutaneous tumors are malignant?
20-40%
List the top 4 most common skin tumors in cats.
basal cell tumor (~25%) > MST > SCC ? fibrosarcoma
Predisposing factors for SCC of the nasal planum, pinna, head and neck in cats?
white fur, UV light
Human syndrome xeroderma pigmentosum (XP) results in UV-induced skin cancer because it is deficient in what type of DNA repair?
nucleotide excision repair
How does papillomavirus result in neoplastic transformation?
- interaction of papilloma viral proteins with cellular proteins
- destabilization of p53 by viral protein E6 and inhibition of pRB by viral protein E7
How is disruption of p53 with E6 characterized on IHC?
increased levels of p16 protein
E6 protein of HPV types 16 and 18 interacts with the E3 ubiquitin protein ligase, resulting in ubiquitination and proteolysis of tumor protein p53. E7 inactivates retinoblastoma protein (Rb) by phosphorylation followed by an increase of free eukaryotic transcription factor E2F (E2F) in the cell. This leads to an increase of cyclin-dependent kinase inhibitor p16, that is used as an immunohistochemical marker of HPV-associated OSCC
What percentage of cutaneous SCC in cats in “UV-protected” (unexposed) areas are positive for papilloma virus via PCR DNA amplification?
76%
vs 42% in UV exposed areas
(no correlation in cats between virus and UV exposure; different in people)
What is the most common skin tumor in dogs?
MCT (~17%)
Which mutation is most common in human SCC?
p53
30% dogs
feline actinic keratosis 79%
feline Bowen’s in situ carcinoma 18%
Which gene is affected by a loss of function mutation in GSD resulting in nodular dermatofibrosis? Which cancer is this associated with?
- Birt-Hogg-Dube (BHD) have to be heterozygous or will die
- renal cystadenocarcinoma
Which RAF sand VEGF/PDGFR TKI is associated with rapid development of actinic keratosis and invasive SCC in people?
sorafenib
Which epithelial membrane glycoprotein is specific for BCC?
BerEP4
Incidence of BCC in dogs? At risk breeds?
- 6%
- Cocker Spaniel, Poodle
Histologic subtypes of BCC?
solid, keratinizing, clear cell
Behavior of BCC in dogs?
- low grade malignancy
- local recurrence possible
- no mets reported
Incidence of BCC in cats? Breeds?
- 10-26%
- Siamese, Himalayans, DLH, Persain
BCC behavior in cats?
- ~10% may be malignant based on stroll invasion, vascular invasion, high MI, LN mets
- pulmonary mets have been reproted
Recommended margins for BCC removal?
5-10 mm surgical
Growth pattern of papillomas?
exophytic
Surgical excision is often curative for papillomas that do not spontaneously regress. Which drug can be used for patients with multiple lesions?
azithromycin
Define SCC in situ.
carcinoma that has not penetrated the basement membrane of the epithelium
Causative agent of carcinoma in situ in cats?
Felis catus PV type 1
- when multiple present termed Bowen’s carcinoma or multicentric Papilloma virus induced carcinoma
What is identified on histopathology for UV induced SCC?
actinic keratosis
DFI and MST for cats with solitary SCC in situ of the nasal planum/pinna treated with surgery alone?
DFI 594d (19.8 mo)
MST 675d (22.5 mo)