Skin & Immune Mediated Disease 1

Question 1

what are the skin defences

Answer 1

1. hair –> thermal insulation & thermal dissipation
2. melanocytes –> photoprotection
3. epidermal barrier –> skin surface lipids & stratum corneum
4. innate immunity
5. adaptive immunity

Question 2

what are the layers of skin

Answer 2

cornified cell envelope

stratum corneum - comeocyte

granular layer - lamellar granules

spinous layer

basal layer

Question 3

how is the physical and permeability barrier of skin regenereated

Answer 3

by process of keratinization –> proliferation + differentiation + cell death

Question 4

what is needed for optimal barrier function

Answer 4

1. lipid bilayer
2. cornified envelope structure
3. filaggrin
4. corneodesmosomes
5. control of desquamation

Question 5

what is the cornified envelope structure

Answer 5

loricrin, involucrin, filaggrin

Question 6

what is filaggrin

Answer 6

formed from profilaggrin (keratohyalin granules)

binds keratin filaments together

breaks down to amino acids (natural moituring factor)

Question 7

whwat is corneodesmosomes

Answer 7

provides structural integrity

Question 8

what is control of desquamation

Answer 8

balance of stratum corneum protease inhibitors & proteases

skin pH

Question 9

what are the portals of entry into the skin

Answer 9

epidermis –> absorption (lipophilic drugs), direct contact (caustic chemicals), colonization (dermatophytes), penetration (hookworm larvae), impaired barrier (micro-organisms, allergens)

Question 10

what is adnexa

Answer 10

entry via follicle ostium

rupture of follicle or adnexal glands

Question 11

what is entry via dermis and panniculus

Answer 11

blood vessels

nerves (rare)

Question 12

what is entry via underlying tissues

Answer 12

penetration by damaged bone

extension from adjacent tissues

Question 13

what are the patterns of skin disease

Answer 13

1. epidemiology (breed, sex, location, season)
2. clinical presentation (lesions, distribution, configuration)
3. histopathology (pattern analysis)

Question 14

what are examples of epidemiology patterns

Answer 14

1. breed (skin fold dermatitis)
2. sex (symmetrical alopecia)
3. location (cutaneous hemangiosarcoma)
4. season (flea allergy dermatitis, more common in temperate climates, seasonal in colder)

Question 15

what are the clinical patterns of skin disease

Answer 15

macroscopic pathology

lesion distribution

lesion discription (size, shape, colour, consistency)

lesion type (inflammatory, hyperplastic, alopecic/hypotrichotic (bald), tumoral/neoplastic (nodular))

Question 16

what is sarcoptic mange

Answer 16

Question 17

what is demodectic mange

Answer 17

Question 18

what are primary skin lesions

Answer 18

develop spontaneously as a result of underlying disease

useful in trying to determine aetiology and pathogenesis of disease

Question 19

what is secondary skin lesions

Answer 19

evolve from primary lesions or induced by self-trauma or external factors

complicate the picture and make diagnoses difficult

Question 20

what is macule, papule, vesicle, pustule, wheal, cyst, nodule

Answer 20

primary skin lesions

1. macule or (>1cm) patch
2. papule or (>1cm) plaque
3. vesicle or (>1cm) bulla
4. pustule (or abscess)
5. wheal (or hive)
6. cyst
7. nodule (1-2cm); tumour (>2cm)

Question 21

what skin lesion is this

Answer 21

macule

a circumscribed, non-palpable spot characterized by a change in the colour of the skin

a larger lesion > 1.0 cm is a patch

Question 22

what skin lesion is this

Answer 22

macule

Question 23

what skin lesion is this

Answer 23

maculopapular rash

a small solid elavation of the skin <1.0cm diameter

Question 24

what skin lesion is this

Answer 24

papule

Question 25

what skin lesion is this

Answer 25

vesicle or bulla sharply cicrumscribed epidermal elevation filled with clear fluid may be intraepidermal or subepidermal a bulla is similar but \>1.0cm diameter

Question 26

what skin lesion is this

Answer 26

vesicle or bulla

Question 27

what skin lesion is this

Answer 27

pustule may be intraepidermal, subepidermal or follicular typically contain neutrophils and bacteria but may contain eosinophils (eosinophilic pustule) and/or be sterile

Question 28

what skin lesion is this

Answer 28

pustule

Question 29

what skin lesion is this

Answer 29

wheal (hive) a circumscribed lesion due to edema, often transient

Question 30

what skin lesion is this

Answer 30

wheal (hive)

Question 31

what skin lesion is this

Answer 31

cyst an epithelium-lined cavity containing fluid or solid (inspissated) material smooth, well circumscribed, usually fluctuant

Question 32

what skin lesion is this

Answer 32

cyst

Question 33

what skin lesion is this

Answer 33

nodule a circumscribed solid elevation that is \>1.0cm diameter usually due to massive cell infiltration that may be inflammatory or neoplastic

Question 34

what skin lesion is this

Answer 34

nodule

Question 35

what skin lesion is this

Answer 35

plaque a large (\>1.0cm) flat-topped elevation formed by extension or coalescence of papules

Question 36

what skin lesion is this

Answer 36

plaque

Question 37

what skin lesion is this

Answer 37

tumour a mass of \>2.0cms that may be neoplastic or non-neoplastic (ex. granulomatous) but term often used to imply neoplasm

Question 38

what skin lesion is this

Answer 38

abscess a localized collection of pus in an area of tissue destruction surrounded by inflammation usually more deeply located than a pustule

Question 39

what skin lesion is this

Answer 39

abscess

Question 40

what are the differentials for a lump in the skin

Answer 40

abscess granuloma cyst neoplasm hematoma

Question 41

what are secondary skin lesion examples

Answer 41

1. epidermal collarette 2. exocriation 3. erosion or ulcer 4. fissure 5. scar 6. lichenification 7. callus

Question 42

what skin lesion is this

Answer 42

collarette a circular rim of scale (loose or peeling keratin) that evolves from a pustule vesicle or bulla

Question 43

what skin lesion is this

Answer 43

collarette

Question 44

what skin lesion is this

Answer 44

excoriation erosions or ulcers caused by self trauma (scratching, rubbing, biting) typically linear they generally indicate pruritus

Question 45

what skin lesion is this

Answer 45

excoriation

Question 46

what skin lesion is this

Answer 46

erosion loss of part of the epidermis, depressed, moist, glistening

Question 47

what skin lesion is this

Answer 47

erosion

Question 48

what skin lesion is this

Answer 48

fissure linear crack or break from the epidermis to the dermis

Question 49

what skin lesion is this

Answer 49

fissure

Question 50

what skin lesion is this

Answer 50

lichenification thickening of the skin with increased creases

Question 51

what skin lesion is this

Answer 51

lichenification

Question 52

what skin lesion is this

Answer 52

crust dead keratinocytes plus neutrophils +/- bacteria

Question 53

what skin lesion is this

Answer 53

crust

Question 54

what skin lesion is this

Answer 54

cutaneous callus localized areas of skin thickening/lichenification develop over pressure points --\> elbow, hocks, sternum (smaller breeds ex. dachshund)

Question 55

what are the causes of skin disease

Answer 55

vitamin d v: vascular i: infectious/inflammatory/immune-mediated t: trauma a: autoimmune m: metabolic/toxic i: intervention/iatrogenic, idiopathic n: neoplastic d: degenerative

Question 56

what are important factors in skin disease

Answer 56

often several overlapping processes may occur together (generalized demodex) most conditions provoke an inflammatory reaction skin is limited in how it can respond