Immune-mediated and Autoimmune Skin Diseases

Question 1

Define autoimmune disease

Answer 1

Specific humoral or cell-mediated immune response against auto(self)-antigens that results in disease

Question 2

Define immune-mediated disease

Answer 2

Used when skin disease is thought to result from inappropriate inflammation or immune attack in the skin but where a specific humoral or cellular response against self-antigens has not been demostrated

Question 3

What determines the type of lesion seen in autoimmune/immune-mediated disease?

Answer 3

Nature and location of auto-antigen and associated inflammatory response

Question 4

Which diseases are characterised by vesicles and bullae?

Answer 4

Diseases that are associated with immune-assaults on the basement membrane or basal keratinocytes
Skin and MM may be affected

Question 5

What do vesicles and bullae end up looking like clinically and why?

Answer 5

Erosions and ulcers as they are very fragile structures

Question 6

What are some examples of immune diseases that attack the basement membrane?

Answer 6

Bullous pemphigoid ad pemphigus vulgaris

Question 7

What is pemphigus foliaceus?

Answer 7

Pustular disease wherein large numbers of neutrophils or eosinophils accumulate within the epidermis and evolve into crusts

Question 8

What characterise diseases classed as subepidermal vesicular autoimmune diseases?

Answer 8

Target antigen is a protein located in the basement membrane leading to a loss of cohesion between the epidermis and dermis frequently associated with the accumulation of inflammatory cells

Question 9

What are the primary and secondary lesions associated with subepidermal vesicular autoimmune diseases?

Answer 9

Vesicles or bullae which rapidly rupture to leave erosions and ulcers

Question 10

Where are lesions of subepidermal vesicular autoimmune diseases located?

Answer 10

Frequently around mucocutaneous junctions, in the axille and groin and may involve the mucous membranes as well

Question 11

What are some examples of subepidermal vesicular autoimmune diseases?

Answer 11

Bullous pemphigoid (BP) - dogs, cats, pigs, horses
Mucous membrane pemphigoid (MMP) - dogs, cats
Epidermolysis bullosa acquisita (EBA) - dogs

Question 12

What are the differential diagnoses for subepidermal vesicular autoimmune diseases?

Answer 12

Other ulcerative autoimmune diseases, drug reactions and epitheliotropic lymphoma

Question 13

What is the classification of pemphigus foliaceus?

Answer 13

Intra-epidermal pustular disease

Question 14

What are the primary and secondary lesions seen with pemphigus foliaceus?

Answer 14

Primary = pustules
Secondary = crusts, scales, hair loss, erosions and epidermal collarettes

Question 15

Where does pemphigus foliaceus tend to affect?

Answer 15

Face (ears often first), feet including footpads and often the groin with the disease tending to become generalised

Question 16

What systemic signs can be seen with pemphigus foliaceus if it is severe?

Answer 16

Fever and depression

Question 17

What is diagnosis of pemphigus foliaceus made on?

Answer 17

History, signs, biopsy, pustule smears

Histopathology is essential

Question 18

What are the histological features of interface dermatitis?

Answer 18

Dermo-epidermal junction is obscured by inflammatory cells or hydropic degeneration or a combination of these features

Question 19

What are some examples of interface dermatitis?

Answer 19

Discoid lupus erythematosus

Erythema multiforme/toxic epidermal necrolysis (TEN)

Question 20

What dogs are predisposed to discoid lupus erythematosus?

Answer 20

Collies, Shelties, GSD and Huskies

Question 21

What are the signs of discoid lupus erythematosus?

Answer 21

Depigmentation, scaling and erythema of nose extending to the bridge of the nose and sometimes affecting the ears and periorbital areas

Question 22

What is an early sign of discoid lupus erythematosus?

Answer 22

Loss of the cobblestone appearance of the nasal planum subsequently with erosion and crusting

Question 23

What is the histopathological appearance of discoid lupus erythematosus?

Answer 23

Cell-rich, lymphocytic interface dermatitis

Question 24

What is the treatment for discoid lupus erythematosus?

Answer 24

Avoid sunlight as it exacerbates the disease, topical fluorinated glucocorticoids twice daily, combined oxytetracycline and niacinamide therapy, Vitamin E, systemic prednisolone in severe cases

Question 25

What are the principles of therapy for autoimmune and immune-mediated skin diseases?

Answer 25

Suppress the autoimmune reaction using anti-inflammatory and immunosuppressive drugs either singly or in combination
Balance severity of disease with severity/likely toxicity of the therapy

Question 26

What is the prednisolone dosage for dogs to control autoimmune/immune-mediated disease?

Answer 26

2-4mg/kg SID initially then maintain on every other day dosing gradually reducing as signs permit

Question 27

What is the dosage of prednisolone for cats to control autoimmune/immune-mediated disease?

Answer 27

Require double the dose of dogs do 4-8mg/kg SID

Question 28

How is azathioprine used to treat autoimmune/immune-mediated disease in dogs?

Answer 28

In combination with systemic prednisolone either as a first line combination or after it has been shown that prednisolone by itself isn’t sufficient

Question 29

What dose of azathioprine is used to treat autoimmune/immune-mediated disease in dogs?

Answer 29

2mg/kg/d orally until a response is obtained and then every other day at this dose for 4-6 weeks then subsequently reduce the dose

Question 30

Why is azathioprine not used to treat cats?

Answer 30

It causes fatal irreversible myelosuppression

Question 31

What is dose of chlorambucil is used to treat pemphigus foliaceus in cats and dogs that don’t respond to prednisolone alone?

Answer 31

0.1-0.2mg/kg every 24-48 hours

Question 32

Why is ciclosporin not used to treat autoimmune/immune-mediated skin disease?

Answer 32

It is too expensive

Question 33

When is tetracycline and niacinamide used to treat autoimmune/immune-mediated disease?

Answer 33

Mild autoimmune diseases where the risk of side-effects of more potent drugs can’t be justified

Question 34

What dose of tetracycline and niacinamide is used to treat autoimmune/immune-mediated diseases? How long does it take to work?

Answer 34

Dogs >10kg = 500mg of each every 8 hours
Dogs <10kg = 250mg TID
Expect effect in 8 weeks

Question 35

What is the aetiology and pathogenesis of feline cowpox?

Answer 35

Orthopox virus with voles and woodmice acting as reservoir hosts so hunters predisposed
Characterisitc clinical entity and is most commonly seen in the autumn when reservoir hosts most active

Question 36

What are the clinical signs of feline cowpox?

Answer 36

Initially a small ulcer or a larger area of abscessation or cellulitis often on the distal limb/face
After 7-10 days multiple nodular lesions develop

Question 37

What are the characteristics of the lesions of feline cowpox?

Answer 37

Typically well-demarcated, raised and erythematous with a vesicular top which rapidly develops into a crust
Some lesions have a central depression or crater

Question 38

How long do feline cowpox lesions take to resolve?

Answer 38

Typically 4-6 weeks

Question 39

How is feline cowpox diagnosed?

Answer 39

Confirmed by virus isolation, electron microscopy on crusts, serology or skin biopsy

Question 40

What features do biopsies with feline cowpox show?

Answer 40

Degenerative changes in the surface and follicular epithelium including the adnexal glands accompanied by a marked dermal infiltrate of inflammatory cells
Characteristic intracytoplasma eosinophilic inclusion bodies

Question 41

How is feline cowpox managed?

Answer 41

No specific antiviral treatment
Supportive symptomatic treatment
Steroids should be avoided as they worsen the disease