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Tobias ECVS > Ch 82 - Disorders of the Skin and Subcutaneous Tissues > Flashcards

Ch 82 - Disorders of the Skin and Subcutaneous Tissues Flashcards

1
Q

What tissue appears most sensitive to healing issues with chemotherapy?
At what stage post-op is it generally recommended to start chemotherapy?

A
  • Intestinal tissue
  • 7-10 days after surgery
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2
Q

What is the general recommendation of timing of radiation therapy before and after surgery?

A
  • After surgery: 1-3 weeks
  • Before surgery: Discontinue for 3-4 weeks (to wait for the acute radiotherapy effect to subside)
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3
Q

List tumour-related factors which may impact wound healing

A
  • Residual neoplastic tissue
  • Tumour-related cytokines
  • Cancer cachexia
  • Paraneoplastic syndromes
  • Tumour size
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4
Q

List the 4 classifications of tumours based on cell origin

A
  • Mesenchymal
  • Epithelial
  • melanocytic
  • round cell
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5
Q

Describe the TNM staging system

A
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6
Q

What is the estimated diagnostic accuracy of FNA cytology of skin neoplasms as compared to histo?

A

Over 90%

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7
Q

How do epithelial and mesenchymal neoplasms tend to metastasise?

A
  • Mesenchymal - haematogenous
  • Epithelial - Lymphatics
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8
Q

What technique can be used for real-time intra-op margin assessment?

A

Near-infrared fluorescense imaging

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9
Q

What sized thoracic nodules can be detected on CT and rads?

A
  • CT: 1-2mm
  • Rads: 5-9mm
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10
Q

What cells make up the germinal centers of a lymph node?

A

B-lymphocytes and plasma cells

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11
Q

List some benefits of lymphadenectomy

A
  • 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 of positive nodes concurrent with excision of grade 2 MCT significantly improved survival
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12
Q

What is a late sequelae of lymphangitis?

A

Irreversible thickening of the skin and SQ (increased macrophages and fibroblasts leading to increased collagen and progressive SQ fibrosis)

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13
Q

What is lymphedema?

A

Interstitial oedema 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 causing a subsequent increase in interstitia volume; hydraulic pressure. Dilation of lymph vessels may also lead to valve insufficiency (dermal backflow)

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14
Q

List underlying abnomalities of primary lymphoedema

A
  • Hypoplasis, aplasia or hyperplasia of distal lymphatics
  • Lymphatic valve incompetence
  • hypoplastic or fibrotic lymph nodes
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15
Q

What are the most common skin tumours of dogs and cats?

A
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16
Q

What mutation is seen in many cases of SCC?

A

UV light-specific mutations in the p53 tumour suppresor gene

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17
Q

List the most common sites of SCC in dogs and in cats

A
  • Dogs: nail bed, scrotum, legs, anus
  • Cats: Pinnae, eyelids, temporal area, nasal planum

White cats have a 13x higher risk

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18
Q

List some alternative treatment methods of SCC stage Tis or T1

A
  • 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

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19
Q

What are the recommended margins for SCC excision in dogs and cats?

A

Dogs: Atleast 2cm (more invasive than cats)
Cats: at least 5mm

20
Q

What breeds are predisposed to hepatoid gland adenomas?

A
  • Cocker Spaniels
  • Beagles
  • Bulldogs
  • Samoyeds
21
Q

What is the overall MST of AGASACA?

A

16-18 months

22
Q

How do anal sac tumours of cats compared with those of dogs?

A
  • Seem to more aggressive with a poorer prognosis. MST after surgery 3 months
23
Q

Describe the TNM classification of STS

A
  • 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
24
Q

In what percentage of cases is pretreatment biopsy accurate in STS?

A
  • Accurate in 59%
  • Overestimated grade in 12%, underestimated in 29%
25
Q

Are STS radiation sensitive?

A

Good outcomes using radiation after incomplete excision or a debulking surgery

26
Q

What is the role of chemotherapy for STS?

A

Unknown….

27
Q

What cells the peripheral nerve sheat tumours (PNST) arise from?
What can be used histologically to differentiate a PNST?

A
  • Arise from Schwann cells, perineural fibroblasts or both
  • Consistently express Vimentin
28
Q

What is a myxosarcoma?

A

A neoplasm arising from fibroblasts or other primitive mesenchymal cells
- Produce an abundant extracellular matrix composed of mucin, rather than collagen

29
Q

What have been associated with feline injection site sarcoma?

A
  • 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
30
Q

What are the recommended margins for injection site sarcoma?

A
  • 5cm lateral marings, 2 fascial planes deep
31
Q

What is the reported recurrence rate after surgical resection of an infiltrative lipoma?

A

36-50%
Can follow with radiation therapy

32
Q

How does timing of spaying effect risk of mammary tumour development?

A
  • Spayed before 1st oestrus - 0.5%
  • Before 2nd oestrus - 8%
  • Before 2yo - 26%

Risk as compared to intact bitch

33
Q

What hormones and growth factors may predispose to mammary tumour development

A
  • Combination of oestrogen and progestin together
  • Growth factor indirectly via IGF-1 and IGF-2
  • Prolactin
34
Q

What genetic factors may be associated with mammary tumours?

A
  • 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
35
Q

For what type of mammary tumour is surgery not recommended

A

Inflammatory carcinoma - highly invasive and high rate of mets, MST 25-60 days

36
Q

Describe the TNM staging of mammary tumours

A
37
Q

What are the surgical options for mammary tumours?

A
  • 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

38
Q

What treatment is available if node mets are confirmed for mammary tumours

A
  • Adjuvant carboplatin chemotherapy
  • Radiation therapy has not been evaluated
39
Q

What is the effect of spaying on development of mammary tumours in cats?

A
  • Reduced by 91% and 86% when spayed by 6m of age and 1yr of age respectively
40
Q

What breeds are predisposed to MCT?

A
  • Boxers
  • Boston Terriers
  • Pugs
  • Bull Terriers
  • Bullmastiffs
  • Cocker Sp
41
Q

WHat mutation is seen in up to 50% of canine MCT?

A

c-kit mutations

42
Q

What MCT locations may be associated with a poorer prognosis?

A
  • Preputial
  • Scrotal
  • Subungal
  • Oral and other mms
  • Perineal and inguinal sites
  • Perioral/muzzle
  • Visceral or bone marrow involvement
43
Q

What special stains can be used for MCT which may help to prognosticate?

A
  • IHC of Ki-67 (nuclear proliferation marker)
  • PCNA
  • AgNOR using silver-based stains
44
Q

What is a cutaneous histiocytoma?

A

A benign skin tumour of the Langerhans cells

45
Q

What is an extramedullary plasmacytoma?

A

Neoplastic proliferation of B-lymphocytes in the skin of mostly the head and limbs

46
Q

In what percentage of cases is pretreatment biopsy accurate in STS in predicting the grade?

A
  • Accurate in 59%
  • Overestimated grade in 12%, underestimated in 29%
47
Q

What is lymphedema?

A

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

Tobias ECVS (110 decks)

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