Skin Sampling

Question 1

What sampling techniques are used for derm?

Answer 1

• skin scrapes
• wood’s lamp
• coat brushing
• hair plucks
• cytology
• tape strips
• smears
• culture
• biopsy

Question 2

What can be demonstrated using skin scrapes?

Answer 2

• ectoparasites (esp mites)
• dermatophytes
• nematodes

Question 3

What size blade should be used for skin scrapes?

Answer 3

No. 10

Question 4

What can be demonstrated using Wood’s lamp?

Answer 4

Certain spp of dermatophyte (most commonly Microsporum canis in vet species)

Question 5

What can be demonstrated using hair plucks?

Answer 5

• Ectoparasites (demodex, esp on feet; lice and mites, eggs ‘nits’)
• Dermatophytes (Hair structure)

Question 6

What can be demonstrated using coat brushing?

Answer 6

superficial ectoparasites esp Cheyletiella and flea feaces

Question 7

What can be demonstrated using tape strips?

Answer 7

• superficial ectoparsites or microbes, esp yeast (Malasezzia: peanut shaped)

Question 8

What can be demonstrated using smears?

Answer 8

• cytology (good for ears, inflammatory lesions, masses)

- microbes (staph or pseudomonas most commonly)

Question 9

What can be demonstrated using biopsy?

Answer 9

• histopath features
• sample for culture
• dont crush sample!!

Question 10

Which derm pathology are Italian Spinonis predisposed to?

Answer 10

Otitis Externa

Question 11

How should skin scrapes/microscope slides be examined?

Answer 11

Methodical exam!!! Snake up and down (marks for this is OSCES)

Question 12

When is skin biopsy indicated?

Answer 12

• neoplasia suspected
• if dx can only be made by histopath
• unusual/severe clinical signs
• persistent ulceration
• no response to initial measures
• expensive/hazardous tx considered

Question 13

Which lesions should be selected for skin biopsy?

Answer 13

> spontaneous, early lesions
- macules, papules, nodules
- pustules, vesicles, bullae
> avoid damaged lesion
- excoriated, scarred
- post-inflammatory pigmentation

Question 14

How should the skin site be prepared for biopsy?

Answer 14

• do NOT Surgically prepare! (removes diagnostic features)
  > exception: tissue culture of nodules
• do not crush sample
• 10% buffered formalin immediately, >20x specimen volume
• remove infection/infestation first? (bacteria/fleas/malasezzia)

Question 15

What size punch biopsies should be used?

Answer 15

• 6/8mm routinely
• 4mm foot pads/nasal planum
• 8mm large lesions
• AVOID NORMAL SKIN!*
  ie. do not aim for ‘margins’

Question 16

When are excisional biopsies indicated?

Answer 16

• lesions of panniculus
• vesicles/bullae
• larger lesions eg. nodules

Question 17

Why should care be taken around dermatophytes cases?

Answer 17

Zoonotic

Question 18

What clinical sign may indicate microbe rather than pure allergy?

Answer 18

Brown exudate discolouration of fur

Question 19

What ectoparasite do rabbits get?

Answer 19

Fur mite

-> salt and pepper appearance of skin

Question 20

What may be found on skin scrap that is diagnositc of Sarcoptes?

Answer 20

Sarcoptes or egg or feacal pellets

Question 21

What is pemphigus folacious?

Answer 21

• autoimmune destruction of desmosomes

- squames and whole cells seen in skin scrapes