History, lesion types, dx techniques

Question 1

what is typical age of onset for atopic dermatitis vs food allergy

Answer 1

atopic dermatitis 1-3 years, food allergy often <1 year
feline atopic syndrome: young
feline food allergy: any age

Question 2

when do endocrine, immune-mediated, and neoplastic issues tend to come up

Answer 2

middle aged or older

Question 3

what are 4 examples of conditions affected by seasonality

Answer 3

atopic dermatitis, clear allergy dermatitis, mosquito bite hypersensitivity

Question 4

with a derm exam, what are some important bits of history to ask about

Answer 4

body site
age of onset
seasonality
environment
dietary history
medications

Question 5

what are primary vs secondary lesions? give a few examples of each

Answer 5

primary = direct manifestation of dz process, eg. pigment change, papule, pustules, vesicles, bulla, nodules, cysts, masses (these can also be secondary)

secondary = lesions that evolve from primary lesion, eg. crusts, epidermal collarettes, erosion/ulceration, comedones, scaling, alopecia, follicular casts

Question 6

what is a macule

Answer 6

macule - flat area of color change < 1 cm diameter

Question 7

what is a patch

Answer 7

patch - flat area of color change > 1 cm diameter

Question 8

what is this

Answer 8

papule = circumscribed elevated skin <1 cm diameter

Question 9

what is this

Answer 9

pustule - circumscribed elevated lesion with pus

Question 10

what is this

Answer 10

plaque = flat-topped, raised skin lesion >1 cm diameter

Question 11

what is this

Answer 11

vesicle = thin walled fluid filled lesion <1 cm diameter
or bulla = as above, but >1 cm

Question 12

what is this

Answer 12

nodule - solid mass > 1 cm diameter

Question 13

what is this

Answer 13

wheal (hives) = flat, firm, raised, emematous lesion, larger and coalescing wheals create angiodema

Question 14

what is this

Answer 14

cyst = epithelial lined cavity containing fluid or cellular, follicular, or sebaceous debris

Question 15

what is this

Answer 15

alopecia (hypotrichosis) = loss of hair

Question 16

what is this

Answer 16

scale = fragments of surface epithelium

Question 17

what is this

Answer 17

crust = accumulation of cellular debris (blood, pus, keratinocytes)

Question 18

what is this

Answer 18

comedones (sn. comedo) = plugged, dilated hair follicles

Question 19

what is this

Answer 19

hypopigmentation = decreased epidermal melanin

Question 20

what is this

Answer 20

hyperpigmentation = increased epidermal melanin

Question 21

what are leukoderma, leukotrichia, melanoderma, melanotrichia

Answer 21

leuko = white, melana = dark
derma = skin, Tricia = hair

Question 22

what is this

Answer 22

epidermal collarette = circular alopecia lesion with peripheral scope and develops from ruptured pustule or bulla

Question 23

what is this

Answer 23

scar = fibrous tissue that has taken place of dermis and subcutus

Question 24

what is this

Answer 24

excoriation = erosion or ulcerations from self trauma

Question 25

what is this

Answer 25

erosion = partial thickness epidermal defect, not to level of dermis or ulcer = full thickness epidermal defect, to level of dermis

Question 26

what is this

Answer 26

lichenification = thickened elephant like skin usually also hyperpigmented

Question 27

what is this

Answer 27

callus = hyperplastic, thickened, alopecia lesions typically on pressure points

Question 28

what is this

Answer 28

erythema - top ddx are allergic inflammation, malasseziasis, bacterial overgrowth

Question 29

what is this

Answer 29

follicular cast

Question 30

what is this? what are a few differentials

Answer 30

nasal planum disease mucocutaneous pyoderma, DLE, mucocutaneous LE, pemphigus foliaceus, pemphigus erythematosis, contact derm, cutaneous lymphoma, drug reaction, uveodermatologic syndrome

Question 31

what are a few differentials

Answer 31

pemphigus foliaceous, hepatocutaneous syndrome, Zn-responsive dermatosis, cutaneous lymphoma, leishmaniasis, distemper, dermatophytosis

Question 32

what are a few differentials (pinnae)

Answer 32

vasculitis, scabies, pineal seborrhoea, pemphigus foliaceus, erythema multiform, pattern alopecia

Question 33

what are some dx techniques you must send to lab

Answer 33

dermatophyte culture or PCR, C&S, biopsy

Question 34

what are 5 skin cytology techniques

Answer 34

tape (best for yeast), slide impression, bread and butter (for exudate), swab impression (for moist lesions), FNA

Question 35

positive pinnal-pedal response se in dog means

Answer 35

scabies

Question 36

what are you looking for with superficial vs deep skin scrape

Answer 36

deep - Demodex (can also use acetate tape technique or trichogram) superficial - scales (Sarcoptes)

Question 37

which will fluoresce under Wood's lamp: Microsporum canis, M. gypsum, Trichotphyton mentagrophytes

Answer 37

M. canis (make sure you let lamp warm up, and know that a true positive is when hair shafts fluoresce; scales, crusts, topical meds, and some abcs can cause false positives)

Question 38

what are some skin scrape alternatives

Answer 38

spatula, trichogram, tape impression, fecal float

Question 39

what are some indications for trichogram

Answer 39

demonstrate pruritus in cats, alopecia, alternative to skin scraping for Demodex, color dilution alopecia, demonstrate fungal elements in dermatophytosis, endocrine disease

Question 40

what are 2 types of dermatophyte culture media

Answer 40

dermatophyte test media (turns red) rapid sporulation agar (turns blue; allows for better speciation) derm-duet płatę has both DTM and RSA

Question 41

compared to culture, dermatophyte PCR has ______ results

Answer 41

discordant

Question 42

what are a few indications for bacterial C&S

Answer 42

lack response to appropriate AMD therapy, pyoderma in dogs with hx of AMD or AMR, deep infection, suspected anaerobic infection, ear culture for non-responsive OE, or OM/OI, atypical bacs suspected

Question 43

what are a few indications for biopsy

Answer 43

suspect immune-mediated or autoimmune disease, severe skin disease, systemic dz suspected, suspect neoplasia, unusual lesions, nodular or deep skin lesions, lack of response to therapy

Question 44

what are some key things to remember about biopsy

Answer 44

do not prep lemon or remove crust rotate in single direction collect with forceps and excise with blade sample only abnormal tissue or centre abnormal tissue, except ulcer multiple samples primary lesions better avoid scars and ulcers alopecia - centre of lesion hypopigmentation - early lesion

Question 45

what

Answer 45

Trichophyton mentagrophytes

Question 46

what is it

Answer 46

Microsporum gypseum

Question 47

what dis

Answer 47

Microsporum canis

Question 48

Scabies will often affect pinnal margins, elbows, and hocks. Flea allergy dermatitis in dogs usually will affect the caudodorsal region. Lice and Cheyletiella both tend to affect the dorsum. Paws, ears, Inguinal, Axillary, cubital fold, periocular, and muzzle are site predilections for dogs with atopic dermatitis and food allergy.