Intro to Derm Flashcards
adnexa
structures that originate from the skin
hairs, claws, sebaceous and sweat glands, arector pili muscle
arector pili muscle
located very close to every hair follicle, primarily on the dorsum
ex: think hackles on a dog
list some functions and properties of the skin
- barrier to loss of water, electrolytes, and molecules
- environmental protection
- allow motion/flexibility while also provide shape and form
- produce adnexa
- thermoregulation
- Vit D production
- sensory perception
- pigmentation
- storage
- antimicrobial
3 Main Layers of the Skin
- Epidermis
- Dermis
- Hypodermis/Subcutaneous
sublayers of the epidermis
from outside –> in
stratum corneum
[stratum lucidum]
stratum granulosum
stratum spinosum
stratum basale (basal layer)
Stratum lucidum is only present where?
only exists on the foot pads and nasal planum
main fxn of the dermis
modulate wound healing and the structure/function of the epidermis
3 Major Phases of the Hair CYcle
- Anagen (growth)
- Catagen (transition)
- Telogen (resting)
there should be constant growth of hair in normal skin
3 dog breeds with continous hair growth
- poodles
- old english sheepdogs
- schnauzers
what is the thickest of the three layers of skin
hypodermis (subcutaneous)
what areas of the body do no have SQ
lip, cheek, eyelid, external ear canal, anus
functions of the hypodermis/SQ
energy reserve, thermogensesis and insulation, protective padding and support
number of epidermal layers in dogs and cats
3 to 5 epidermal layers
normal turnover of skin in dogs?
in days
21-22 days
assumed to be similar in cats but cats have not been studied
if there is scaling/flaking, what does that say about skin turnover?
the rate of turnover is TOO FAST
how do the # of epidermal layers, turnover time, and the pH of skin in dogs and cats compare to humans?
humans have more epidermal layers, a longer turnover time, and a lower pH
10-15 epidermal layers
28+ day turnover
pH 5.5
pH of dog skin? cats?
dog pH = 7.5
cat pH = 6-7
how do immune-mediated/hormone lesions tend to be distrubuted?
symmetrically
What are the 12 primary dermatologic lesions?
primary meaning a direct result of the underlying disease
- macule
- papule
- plaque
- pustule
- vesicle
- nodule
- wheal
- cyst
- alopecia
- scale
- crust
- comedone
which of the 12 primary dermatologic lesions can ALSO be secondary? (4)
- alopecia
- scale
- crust
- comedone
identify
*yellow circle is location for punch biopsy, not the lesion you are IDing
macule
a macule larger than 1cm in diameter is called a patch
identify
*yellow circle is location for punch biopsy, not the lesion you are IDing
papule
identify
*yellow circle is location for punch biopsy, not the lesion you are IDing
plaque
identify
*yellow circle is location for punch biopsy, not the lesion you are IDing
wheal
identify
*yellow circle is location for punch biopsy (though is preferred to be excised), not the lesion you are IDing
nodule
identify
*biopsy is excisional
cyst
identify
*yellow circle is location for punch biopsy, not the lesion you are IDing
vesicle
identify
*yellow circle is location for punch biopsy, not the lesion you are IDing
pustule
Define
macule
flat circumscribed lesion associated with color change
less than 1cm diameter
define
papule
solid elevation of skin
less than 1cm diameter; can have some erythema
define
erythema
inflammation of skin
define
plaque
flat-topped, thickened elevation greater than 1cm formed by coalescing papules or dermal infiltration
define
pustule
circumscribed epidermal elevation of skin filled with pus
define
vesicle
fluid-filled (serum) elevation fo the epidermis, less than 1cm
larger than 1cm is called a bulla
SKP this is like your stupid hands
define
nodule
solid elevation greater than 1 cm
dermal nodules must be physically palpated to be identified
define
wheal
sharply circumscribed elevation in the skin associated with edema
this is what you see with intradermal testing
define
cyst
epidermal-lined cavity containing fluid or solid material
ex: sabceous (waxy) cysts
the “cover” is thicker/less fragile than a vesicle or pustule
identify
comedone
blackheads in humans
identify
scale
identify
*yellow circle is location for punch biopsy, not the lesion you are IDing
crust
define
alopecia
partial (hypotrichosis) to complete loss of hair
primary causes of alopecia
endocrine diseases, follicular dysplasia
define
scale
accumulation of loose stratum corneum
from fast skin-cycling/turnover
owners will call this “dandruff”
define
crust
accumulation of dried exudate, leratin, serum, blood cells, scales, or even meds adherent to the skin suface
there should be something moist/exudative under the crust when sampled
define
comedone
dilated hair follicle filled with cornified cells and sebaceous material
skin cells in contact with the air become DARK
What are the 10 primary dermatologic lesions?
- alopecia
- scale
- crust
- comedone
- epidermal collarette
- erosion
- ulcer
- excoriation
- lichenification
- scar
which of the 10 secondary dermatologic lesions can ALSO be primary? (4)
- alopecia
- scale
- crust
- comedone
identify
*yellow circle is location for punch biopsy, not the lesion you are IDing
erosion
identify
*yellow circle is location for punch biopsy, not the lesion you are IDing
ulcer
identify
excoriation
identify
lichenification
identify
epidermal collarette
define
epidermal collarette
circular scale or crust with erythema
remnant of a pustule or vesicle
MUST have erythema
define
erosion
shallow epidermal defect that does NOT penetrate the dermis
technically histopath is needed to differentiate it from an ulcer
define
ulcer
break in continuity of the epidermis with EXPOSURE of the underlying dermis
deeper than erosions
define
excoriation
lesion caused by scratching, biting, rubbing
define
lichenification
thickening of the epidermis; exaggerated texture due to chronic inflammtion
define
scar
fibrous tissue replacing damaged cutaneous and/or subcutaneous tissues
shiny appearance due to fibroblasts trying to replace the lost tissue
no dermis or epidermis –> no hair regrowth
6 Different Diagnostic Tests for Skin
- skin scrapings
- cytology
- trichogram
- dermatophyte culture
- bacterial culture
- biopsy/histopathology
purpose of skin scrapings?
to diagnose mites
not bacteria or yeast or inflammatory cells
can cytology diagnose mites?
no
different ways to sample for cytology
skin - impression smear, tape, swab
ear - swab
nodules - FNA
does cytology always have to be stained?
yes
3 reasons for a trichogram
- evaluate anagen/telogen ratio
- investigate barbering
- diagnosis dermatophytosis, (also demodex in areas you can’t scrape i.e. periocular)
what sample is the toothbrush used for
dermatophyte culture
blue canoes
can you just do bacterial culture willy nilly?
no, you should do cytology first and confirm you even have bacteria present you dummy
what do the numbers on the punch biopsies indicate?
size
smaller # = smaller punch
typically we use a 6 or 8 for skin
