Scaling and Crusting

Question 1

Define scale

Answer 1

An accumulation of loose cornified fragments of the stratum corneum

Question 2

Define crust

Answer 2

Presence of dried exudate on the skin surface

Question 3

What is follicular casting?

Answer 3

Thickened stratum corneum around hair shaft

Question 4

What is the most common cause of follicular casting?

Answer 4

Demodecosis

Question 5

What is a comedo?

Answer 5

Sebaceous gland filled with keratinised debris

Question 6

What can cause comedomes?

Answer 6

Demodecosis, endocrine disease or as a primary defect of cornification

Question 7

What is seborrhoea?

Answer 7

Flow of sebum

Vague clinical term for scaling/greasy exudation

Question 8

What is seborrhoea sicca?

Answer 8

Dry scaling

Question 9

What is seborrhoea oleosa?

Answer 9

Oily scaling

Question 10

What is seborrhoeic dermatitis?

Answer 10

Greasy, inflamed skin

Question 11

What do defects of cornification refer to?

Answer 11

Skin diseases where scaling/follicular casting is a dominant clinical feature

Question 12

What are some causes of secondary defects of cornification?

Answer 12

Parasites, infection, nutrition, allergy, neoplasia

Question 13

What are some primary causes of defects of cornification?

Answer 13

Idiopathic or genetic defect

Question 14

What is spaniel seborrhoea?

Answer 14

Primary defect affecting Cocker Spaniels resulting in increased mitotic rate/decreased turnover time

Question 15

What do skin grafts of animals with spaniel seborrhoea do?

Answer 15

Remain hyperproliferative resulting in localised or generalised scaling/casting

Question 16

How is spaniel seborrhoea diagnosed?

Answer 16

Exclude primary causes and biopsy

Question 17

What is the treatment for spaniel seborrhoea?

Answer 17

Shampoo 2x a week to remove excess scale
Vitamin A (there is a vit A responsive form)
Retinoids (synthetic vit A derivatives) - caution highly teratogenic

Question 18

What is sebaceous adenitis?

Answer 18

Sebaceous glands are destroyed causing generalised scaling/casting and varying alopecia as it can interfere with normal hair growth

Question 19

How is sebaceous adenitis diagnosed?

Answer 19

Exclude secondary causes and biopsy

Question 20

What is the treatment for sebaceous adenitis?

Answer 20

Shampoo, EFA (fatty acids), cyA (cyclosporine not licensed but considered under cascade)
Can use retinoids but teratogenic

Question 21

What is crusting a consequence of?

Answer 21

Epidermal inflammation due to a severe oedematous response or marker cellular recruitment

Question 22

What are common triggers of crusting?

Answer 22

Physical damage, infection or infestation

Question 23

What are the differential diagnoses for pruritic, steroid-resistant crusting lesions?

Answer 23

Scabies, pemphigus, dermatophytosis, cutaneous lymphoma

Question 24

What is the diagnostic plan for pruritic, steroid-resistant crusting lesions?

Answer 24

Skin scrapings

Question 25

What is the treatment for scabies?

Answer 25

Amitraz weekly for 6 weeks, body clip if long haired, prednisolone 0.75mg/kg SID for 10 days, cephalexin 20mg/kg BID for 3 weeks

Question 26

Why can topical drug treatments fail?

Answer 26

Doesn't reach skin of long haired dogs | Washed off before it can be absorbed in sufficient conc.

Question 27

What are the DDx for dogs with lameness, lethargy, inappetance, PU/PD, weight loss, progressive skin disease and interdigital dermatitis?

Answer 27

Superficial necrolytic dermatitis, pemphigous foliaceus, systemic lupus erythematosus, drug eruption, erythema multiforme

Question 28

What are the synonyms for superficial necrolytic dermatitis?

Answer 28

Diabetic dermatosis, hepatocutaneous syndrome, metabolic epidermal necrosis, necrolytic migratory erythema

Question 29

What is superficial necrolytic dermatitis?

Answer 29

Uncommon erosive, crusting, ulcerative disease which commonly affects the footpads, extremities and periorificial skin of middle-aged and old dogs

Question 30

How is superficial necrolytic dermatitis (SND) diagnosed?

Answer 30

Rule out parasites Haematology and biochemistry Skin biopsy - pallor (oedema, hydropic degeneration) of upper epidermis, ortho/parakeratotic hyperkeratiosis, superficial dermal infiltration (mononuclear cells) Ultrasound = diffuse hypoechogenic areas in liver

Question 31

What is the pathogenesis of SND?

Answer 31

Seen with hepatic disease or pancreatic glucogonoma | Bile acids and ultrasound may help differentiation of underlying disease

Question 32

What is the prognosis of SND?

Answer 32

Poor