Disorders of the Skin and SQ Flashcards
What tissue appears most sensitive to healing issues with chemotherapy?
At what stage post-op is it generally recommended to start chemotherapy?
- Intestinal tissue
- 7-10 days after surgery
What is the gereral recommendation of timing of radiation therapy before and after surgery?
- After surgery: 1-3 weeks
- Before surgery: Discontinue for 3-4 weeks
List tumour-related factors which may impact wound healing
- Residual neoplastic tissue
- Tumour-related cytokines
- Cancer cachexia
- Paraneoplastic syndromes
- Tumour size
List the 4 classifications of tumours based on cell origin
- Mesenchymal
- Epithelial
- melanocytic
- round cell
Describe the TNM staging system
What is the estimated diagnostic accuracy of FNA cytology of skin neoplasms as compared to histo?
Over 90%
How do epithelial and mesenchymal neoplasms tend to metastasise?
- Mesenchymal - haematogenous
- Epithelial - Lymphatics
What technique can be used for real-time intra-op margin assessment?
Near-infrared fluorescense imaging
What sized thoracic nodules can be detected on CT and rads?
- CT: 1-2mm
- Rads: 5-9mm
What cells make up the germinal centers of a lymph node?
B-lymphocytes and plasma cells
List some benefits of lymphadenectomy
- LN mets may act as a surce for further spread
- Could slow down rate of mets
- May reduce paraneoplastic disease
- Part of debulking procedure
- Lymphadenectomy pf positive nodes concurrent with excision of grade 2 MCT significantly improved survival
What is a late sequelae of lymphangitis?
Irreversible thickening of the skin and SQ (increased macrophages and fibroblasts leading to increased collagen and progressive SQ fibrosis)
What is lymphedema?
Interstitial oedeme characterised by an imbalance between net capillary filtration and lymphatic return of interstitial fluid
WIth lymphatic stasis, macromolecular proteins and metabolites accumulate in the interstitial space. This increased oncotic pressure draws more water out causin a subsequent increase in interstitia; hydraulic pressure. Dilation of lymph vessels may also lead to valve insufficiency
List underlying abnomalities of primary lymphoedema
- Hypoplasis, aplasia or hyperplasia of distal lymphatics
- Lymphatic valve incompetence
- hypoplastic or fibrotis lymph nodes
What are the most common skin tumours of dogs and cats?
What mutation is seen in many cases of SCC?
UV light-specific mutations in the p53 tumour suppresor gene
List the most common sites of SCC in dogs and in cats
- Dogs: nail bed, scrotum, legs, anus
- Cats: Pinnae, eyelids, temporal area, nasal planum
White cats have a 13x higher risk
List some alternative treatment methods of SCC stage Tis or T1
- Cryotherapy - small, superficial lesions up to 5mm
- Plesiotherapy (strontium 90) - superficial lesions, only 10% of original dose reaches 3mm of depth
- Radiation Therapy
- Photodynamic therapy - topical 5-aminolevulinic acis or systemic meta-tetrahydroxyphenylchlorin for superficial lesions
- Electrochemotherapy - bleomycin
- NSAIDs
- Immunomodulatory therapy - Imiquimod, indirect antiviral and antitumour effects
Aggressive surgert is best for stage T2 or higher
What are the recommended margins for SCC excision in dogs and cats?
Dogs: Atleast 2cm (more invasive than cats)
Cats: at least 5mm
What breeds are predisposed to hepatoid gland adenomas?
- Cocker Spaniels
- Beagles
- Bulldogs
- Samoyeds
What is the overall MST of AGASACA?
16-18 months
How do anal sac tumours of cats compared with those of dogs?
- Seem to more aggressive with a poorer prognosis. MST after surgery 3 months
Describe the TNM classification of STS
- Stage I: G1-2, Any T, N0, M0
- Stage II: G3, T1a/b, T2a, N0, M0
- Stage III: G3, T2b, N0, M0
- Stage IV: N1 or M1
In what percentage of cases is pretreatment biopsy accurate?
- Accurate in 59%
- Overestimated grade in 12%, underestimated in 29%
Are STS radiation sensitive?
Good outcomes using radiation after incomplete excision or a debulking surgery
What is the role of chemotherapy for STS?
Unknown….
What cells to PNST arise from?
What can be used histologically to differentiate a PNST?
- Arise from Schwann cells, perineural fibroblasts or both
- Consistently express vimentin
What is a myxosarcoma?
A neoplasm arising from fibroblasts or other primitive mesenchymal cells
- Produce an abundant extracellular matrix composed of mucin, rather than collagen
What have been associated with feline injection site sarcoma?
- Inactivated vaccines (Rabine, FeLV)
- Other multivalen vaccines
- Long actine pencillins inj
- Long acting corticosteroid inj
- nonabsorbable sutures
- Cisplatin inj
- Meloxicam inj
- Microchips
- Steel skin staples
- Retained surgical sponge
What are the recommended margins for injection site sarcoma?
- 5cm lateral marings, 2 fascial planes deep
What is the reported recurrence rate after surgical resection of an infiltrative lipoma?
36-50%
Can follow with radiation therapy
How does timing of spaying effect risk of mammary tumour development?
- Spayed before 1st oestrus - 0.5%
- Before 2nd oestrus - 8%
- Before 2yo - 26%
Risk as compared to intact bitch
What hormones and growth factors may predispose to mammary tumour development
- Combination of oestrogen and progestin together
- Growth factor indirectly via IGF-1 and IGF-2
- Prolactin
What genetic factors may be associated with mammary tumours?
- Overexpression of protooncogene c-erb-2
- p53 tumour suppressor gene mutations
- expression of tumour suppressor genes BRCA1 and BRCA2 and RAD4
- Overexpression of adhesion moledules CD44
- Decreased expression of E-cadherin
- VEGF expression for angiogenesis
- COX2 expression
- Obesity at 1yo or younger
For what type of mammary tumour is surgery not recommended
Inflammatory carcinoma - highly invasive and high rate of mets, MST 25-60 days
Describe the TNM staging of mammary tumours
What are the surgical options for mammary tumours?
- Lumpectomy - small under 0.5cm tumours, known to be benign
- Simple mastectomy - Small, centrally located tumours for which mastectomy achieves 2-3cm margins
- Regional mastectomy - En bloc removal of glands 1-3 or 3-5
- Chain mastectomy - multiple nodules, tumours in the 3rd gland, or large masses over 1cm with fixation or otherwise suspicious for malignancy. Unilateral or staged bilateral
Radical mastectomy is recommended in cats regardless of tumour size
What treatment is available is node mets are confirmed for mammary tumours
- Adjuvant carboplatin chemotherapy
- Radiation therapy has not been evaluated
What is the effect of spaying on development of mammary tumours in cats?
- Reduced by 91% and 86% when spayed by 6m of age and 1yr of age respectively
What breeds are predisposed to MCT?
- Boxers
- Boston Terriers
- Pugs
- Bull Terriers
- Bullmastiffs
- Cocker Sp
WHat mutation is seen in up to 50% of canine MCT?
c-kit mutations
What MCT locations may be associated with a poorer prognosis?
- Preputial
- Scrotal
- Subungal
- Oral and other mms
- Perineal and inguinal sites
- Perioral/muzzle
- Visceral or bone marrow involvement
What special stains can be used for MCT which may help to prognosticate?
- IHC of Ki-67 (nuclear proliferation marker)
- PCNA
- AgNOR using silver-based stains
What is a cutaneous histiocytoma?
A benign skin tumour of the Langerhans cells
What is an extramedullary plasmacytoma?
Neoplastic proliferation of B-lymphocytes in the skin of mostly the head and limbs
In what percentage of cases is pretreatment biopsy accurate?
- Accurate in 59%
- Overestimated grade in 12%, underestimated in 29%
What is lymphedema?
Interstitial oedeme characterised by an imbalance between net capillary filtration and lymphatic return of interstitial fluid
WIth lymphatic stasis, macromolecular proteins and metabolites accumulate in the interstitial space. This increased oncotic pressure draws more water out causin a subsequent increase in interstitia; hydraulic pressure. Dilation of lymph vessels may also lead to valve insufficiency
