Approach to pustular, papular, scaling and crusting skin disease

Question 1

Define Papule?

Answer 1

Small solid elevation of skin <1cm diameter

Often erythematous

May –> crusts of serum, pus or blood ( in that case would be papules courteous lesions)

Over a 1cm they are called nodules

Question 2

Define pustule?

Answer 2

Small (<1cm) skin elevation, filled with pus

Often start as papule

Bigger than a 1 cm is a bullae or vesicle

Question 3

Pustules are not always in same place they can be?

Answer 3

Question 4

Pustules are very fragile so rarely seen (deeper lesions less fragile than superficial) they are usually seen as?

Answer 4

epidermal collarettes

(rupture end point of pustule)

(circular spreading ring of crusts due to exfoliative process)

Question 5

Name Pustular/papular diseases in dogs?

Answer 5

Big 3 in bold

Autoimmune diseases have sterile pustules

Question 6

Name pustular/papular diseases in cats?

Answer 6

Common in bold

Question 7

What are the causes of miliary dermatitis in cats?

Answer 7

Very common! If you cant think of anything else to do treat for fleas

Question 8

What history do you need to know to approach pustular, papular, scaling and crusting skin disease?

Answer 8

• Breed
• Age of onset
• In-contact animals/humans affected
• Pruritus:
  
  • presence/absence, severity
  • preceded or followed lesion development
• Course of disease
• Seasonality
• Response to past treatment, including parasiticides
• Results of prior tests
• Concurrent systemic signs
• Travel abroad

Question 9

How should you approach a case showing pustular and papular pathology?

Answer 9

Question 10

If after this process of procedures outlined in attached image microbial and parasitic infection is eliminated how next should you deal with pustule and papular lesions?

Answer 10

Question 11

What is scale?

Answer 11

• Scale (dandruff to the man on the street)
• = Rafts of immature keratinocytes which accumulate at the skin surface
• Due to hyperkeratosis (increased depth of cornified layer) (See ‘Pruritus and dermatological response to disease’ ENI1)
• Caused by increased or disrupted epidermal turnover
• Loose or tightly adherent
• Form scurf when desquamate

Question 12

What are the 2 types of scale?

Answer 12

Parakeratotic hyperkeratosis

• cells in the scale have nuclei
• Rare Eg
• Malassezia dermatitis
• zinc-responsive dermatosis
• superficial necrolytic dermatitis

Orthokeratotic hyperkeratosis

• Increase in normal keratinocytes
• Common inflammatory disorders, keratinisation disorders
• nO nuclei

Question 13

What is crust?

Answer 13

Always a secondary lesion

• When exudates (serum, pus or blood) dry on skin surface
• Often also involves surface squames, hair, topical medications
• Can therefore be associated with
  
  • scaling
  • pustular
  • ulcerative/erosive diseases

Question 14

What is the diagnostic approach for scaling and crusting?

Answer 14

Question 15

If none of the diagnostic approachs shown in image below yield any results what would you do next?

Answer 15

Question 16

What are primary keratinisation disorders?

Answer 16

Defects in normal keratinisation process

• abnormal formation of keratinocytes
• abnormal sebaceous gland function

Rare; often breed-related; tend to occur in younger animals

Diagnosis of exclusion

Treat symptomatically

Everything apart from the primary keratinisation disorders are secondary.​

Question 17

Name primary keratinisation disorders in dogs?

Answer 17

Question 18

What is Idiopathic seborrhoea?

Answer 18

A primary idiopathic keratinisation disorder

Seen commonly in spaniels

Scaling, often thick and adherent

Erythema, greasy scale of lips, periocular skin, ventral neck/body, feet, tail; otitis externa

Secondary pyoderma and Malassezia dermatitis common

Question 19

What is Ichthyosis?

Answer 19

A Primary idiopathic keratinisation disorder

Ichthyosis (‘fish scale disease’)

Golden retriever

• Often young dogs
• No other clinical signs, unless
• secondarily-infected

What kate sees a lot is icthyosis in golden retrievers.

Ichthy: is greek for fish. The dogs look like they have fish scales.

Question 20

What is Nasodigital hyperkeratosis?

Answer 20

A primary keratinisation disorders in dogs

Cocker/Springer spaniels and old dogs

Also can be seen with hypothyroidism, pemphigus foliaceus, cutaneous lupus, NME, distemper, Zn-responsive dermatosis

Frond-like hyperkeratosis that may fissure and become infected

Treat: warm-water soaks, topical salicylic acid (karyolytic) , propylene glycol (moistureriser), 0.5% tretinoin

Question 21

What is a callus?

Answer 21

Callus

On bony prominences in heavy dogs on hard surfaces

Normal protection mechanism but can also fissure and become infected

Treatment

Don’t excise!

As for naso-digital hyperkeratosis

Control infection

Encourage to lie on soft bedding

DogLeggs?

Involves..

Hyperkeratosis

Increased depth of cornified layer

+

Acanthosis

Increased depth of epidermis

Question 22

Name primary keratinisation disorders in cats?

Answer 22

Not common

Question 23

What is feline acne?

Answer 23

Dark waxy scales on chin

May be primary disorder, but often secondary (e.g. to dermatophytosis, demodicosis)

Often develop secondary Malassezia, pyoderma and furunculosis

Treatment depends on cause. Includes:

• Chlorhexidine or chlorhexidine/miconazole washes
• Antiseborrheic washes (dissolve crust and scale)
• Topical antibiotics, eg fusidic acid if secondarily infected (occasionally systemic antibiotic)
• Neutering
• Benzoyl peroxide product? (sparing as potentially toxic/irritant/bleaching; veterinary products no longer available)
• 0.5% tretinoin (topical retinoid)? – unlicensed

Question 24

What is the cause of this secondary keratinisation disorder?

Answer 24

Neoplasia:

Exfoliative dermatitis secondary to thymoma

(paraneoplastic syndrome)

Question 25

What has caused this secondary keratinisation disorder?

Answer 25

Epitheliotropic lymphoma

Question 26

What is the cause of this secondary keratinisation disorder?

Question 27

What is the cause of this secondary keratinisation disorder?

Question 28

What is Sebaceous adenitis?

Answer 28

Standard Poodle, Akita, Samoyed, Viszla, English Springer Spaniel, occ others * Inflammation of sebaceous glands --\> gland destruction * Tightly-adherent frond-like scale, follicular casts * Hair loss * Generalised, focal or multifocal * Often secondarily-infected --\> pruritus * Need multiple biopsies often to diagnose * Treatment of choice = ciclosporin. Otherwise symptomatic control * Way we look at them is rule out infection and then biopsy.

Question 29

What is this and what does it resemble?

Answer 29

Leishmaniasis Looks similar to sebaceous adenitits.

Question 30

What is superficial necrolytic dermatitis?

Answer 30

(= necrolytic migratory erythema = hepatocutaneous syndrome = metabolic epidermal necrosis) Secondary to end-stage liver disease, pancreatic atrophy, glucagonomas, diabetes mellitus Affects joints, pressure-points, lips, feet Erythematous plaques/erosions covered with thick adherent scale

Question 31

How should scaling and crusting disease be treated?

Answer 31

Where possible address underlying disease. But symptomatic management frequently required. Anti seborrhoeic shampoos: **Keratolytic** – reduce cohesion between cells of stratum corneum **Keratoplastic** – restore normal epidermal epithelialisation and keratinisation; reduce skin turnover Degreasing Aim to use the mildest effective product – minimises risk of drying effect. Follow with moisturising rinse if necessary

Question 32

What are the various ingredients in different anti-seborrhoeic shampoos?

Answer 32

Question 33

Name emollients and what do they do?

Answer 33

Soften and soothe skin Reduce trans-epidermal water loss e.g. Vaseline, lanolin, paraffin, vegetable and animal oils

Question 34

Name moisturisers and what they do?

Answer 34

**Moisturisers** Increase water content of stratum corneum, e.g. * urea * sodium lactate * colloidal oatmeal * glycerine * propylene glycol (can use 1:1 with water as spray for sebaceous adenitis) * lactic acid * ammonium lactate

Question 35

If emollients and moisturisers dont work to treat scaling and crusting what is the next step?

Answer 35

**Retinoids** (chemicals with Vitamin A activity) Anti-proliferative, anti-inflammatory, immune-modulatory **_Systemic_** **Vitamin A** For vitamin-A responsive dermatosis (form of idiopathic keratinisation disorders in Cocker Spaniels) **Isotretinoin, Acitretin** Significant side-effects (highly teratogenic, KCS, joint pain, vomiting, diarrhoea, dry skin, hyperostosis) Use under consultant dermatologist’s guidance only **Topical** Tretinoin 0.5% (unlicensed) **Ciclosporin** used in sebaceous adenitis (off-label use)