Dermatology Flashcards
18month male neutered Daschund has been itching and scratching over the lumbar-sacral region for a week
Exam shows erythema, excoriation, and alopecia
What would your problem list be and DDX for this patient?
Problem list
- alopecia
- moderate excoriation/hyperaemia
- severe pruritus
DDX
- flea bite hypersensitivity
- demodecosis
- superficial bacterial pyoderma
18month male neutered Daschund has been itching and scratching over the lumbar-sacral region for a week
Exam shows erythema, excoriation, and alopecia
What would your further work up include?
Skin scrape
Plucks
Smear
Fetal dirt test
What are primary skin lesions
Initial eruption that develops as a reflection of the underlying dz
Macula/patch Papule/plaque Pustule Vehicle/bulla Wheal Nodule Tumor/cyst
What is a secondary skin lesion?
Evolve from primary lesions or are induced by patient/external factors
Epidermal collarette Scar Excoriation Erosion or ulcer Lichenification Callus
What lesions can be either primary or secondary?
Alopecia Scale Crust Follicular casts Comedone Pigmentary abnormalities
Flat spot <1cm on skin with change in skin colour
Macule
Flat spot >1cm on skin with change in colour
Patch
What are types of macules caused by bleeding into the skin ?
Purpura
Petechia
Ecchymosis
Small solid elevation in skin up to 1cm
Papule
Coalition of papules forming a flat topped elevation
Plaque
Hot spot -red and inflamed
Elevation of epidermis with clear fluid (<1cm)
Vehicle
Elevation of epidermis with clear fluid >1cm
Bulla
Sharply delineated lesion of edema
Wheal
Solid raised palpable lesions >1cm
These can include…?
Nodule
Abscess, cyst, tumor, or granuloma
Absence of hair from a normally a haired area
Alopecia
Accumulation of loose fragments of horny layer of skin
Scale
Accumulation of dried serum, exudate on surface of skin
Crust
Accumulation of keratin and sebaceous material stuck to a hair shaft
Follicular casts
Dilated hair follicle with debris
Comedone
Scale arranged in a circular pattern?
This lesion is associated with reminants of what other lesions?
Epidermal collarette
Pustule, vesicle, or bullae
Fibrous tissue has replaced the damaged dermis or s/c tissue
Scar
Linear abrasion of the skin
Excoriation
Shallow ulcer that does not break basal layer?
Erosion
Break in epidermis with exposure of dermis
Ulcer
Linear cleavage (cracks) in the epidermis or dermis caused by disease or injury
Fissure
Thickening and hardening of the skin
Lichenification
A localized hyperplasia of the stratum corneum of the epidermis caused by pressure or friction. Common on elbows and lateral hock.
Callus
What laboratory tests are available for skin conditions?
Superficial/deep skin scrap Hair pluck Surface skin cytology Bacteria culture and sensitivity Comb for flea Woods lamp/ fungal culture Scotch tape test Fecal float Skin biopsy
What is the method used for a superficial skin scrape?
What can you find with this?
Moisten blade with liquid paraffin/ KOH/ mineral oil
Scrape a large area, with 3 passes of the blade
Surface mites
- sarcoptes
- notoedres
- otodectes
- cheyletiella
- Demodex gatoi in cat
What is the method for a deep skin scrape and what would you be looking for?
Scrape a small focal area with dulled blade using mineral oil
- induce capillary hemorrhage
- squeeze follicles
Follicular parasites
-demodex
You do a hair pluck/trichogram. What are you looking for?
Ring worm - hyphae or spores
Follicle dysplasia
Surface parasite (lice or mites)
What is the method for acetate tape impression smear. What would you be able to visualize?
Scotch tape test —> onto microside —> add 1drop of diff quick
Can see bacteria, fungi, or yeast
Why would you do a fecal float in a dermatology cases?
Worms can migrate through the skin — cutaneous larval migrans
Hookworms - ancylostoma or uncinaria
What is the technique used for skin FNA?
21-23g needle
Attached to 5ml syringe
Put needle in lesion, aspirate, pull needle out a bit
Redirect into another site, aspirate
Release pressure on needle before withdrawing
Disconnect needle from syringe, add few ml of air to syringe. Reattached to needle and express content of needle onto microscope slide
Woods lamps can produce false positives with what?
Keratin scale
Soap
Dyes
Medications
When would you do a fungal culture?
All cats with skin dz
Dogs with inflammatory skin lesions
What lesion sampling will you do for fungal culture?
Woods lamp —> pluck hairs that fluoresce for DTM inoculation
If no fluorescence —> comb with toothbrush to collect hair and scale
DTM is test of choice -> must check everyday
—>Can turn red if a days after a saprophytic colony grows (non-pathogenic)
—> Will turn red the SAME day if a dermatophyte colony grows (pathogenic)
What are indications for skin biopsy?
Nodule/tumor Ulcer/vesicle Severe acute generalized dz Mucosal lesions Footpad lesions Lesions unresponsive to normal therapy
How will you do your skin biopsy
No prep, no scrub
Gently clip hair
Handle sample as little as possible
Place in formalin and culture pot
Can do
- punch biopsy
- wedge/excisional
- amputation (nail or toe)
What are indications for bacterial culture and sensitively?
Cytology shows cocci and rods Or just rods
Cocci but no response to right AB administered at right dose
Deep pyoderma
Chronic AB/GC therapy
GSD pyoderma
T/F: allergy testing serology is reliable for food allergies
False
