Approach to pustular, papular, scaling and crusting skin disease Flashcards
Define Papule?
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
Define pustule?
Small (<1cm) skin elevation, filled with pus
Often start as papule
Bigger than a 1 cm is a bullae or vesicle
Pustules are not always in same place they can be?
Pustules are very fragile so rarely seen (deeper lesions less fragile than superficial) they are usually seen as?
epidermal collarettes
(rupture end point of pustule)
(circular spreading ring of crusts due to exfoliative process)
Name Pustular/papular diseases in dogs?
Big 3 in bold
Autoimmune diseases have sterile pustules
Name pustular/papular diseases in cats?
Common in bold
What are the causes of miliary dermatitis in cats?
Very common! If you cant think of anything else to do treat for fleas
What history do you need to know to approach pustular, papular, scaling and crusting skin disease?
- 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
How should you approach a case showing pustular and papular pathology?
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?
What is scale?
- 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
What are the 2 types of scale?
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
What is crust?
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
What is the diagnostic approach for scaling and crusting?
If none of the diagnostic approachs shown in image below yield any results what would you do next?
What are primary keratinisation disorders?
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.
Name primary keratinisation disorders in dogs?
What is Idiopathic seborrhoea?
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
What is Ichthyosis?
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.
What is Nasodigital hyperkeratosis?
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
What is a callus?
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
Name primary keratinisation disorders in cats?
Not common
What is feline acne?
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
What is the cause of this secondary keratinisation disorder?
Neoplasia:
Exfoliative dermatitis secondary to thymoma
(paraneoplastic syndrome)
What has caused this secondary keratinisation disorder?
Epitheliotropic lymphoma
What is the cause of this secondary keratinisation disorder?
What is the cause of this secondary keratinisation disorder?
What is Sebaceous adenitis?
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.
What is this and what does it resemble?
Leishmaniasis
Looks similar to sebaceous adenitits.
What is superficial necrolytic dermatitis?
(= 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
How should scaling and crusting disease be treated?
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
What are the various ingredients in different anti-seborrhoeic shampoos?
Name emollients and what do they do?
Soften and soothe skin
Reduce trans-epidermal water loss
e.g. Vaseline, lanolin, paraffin, vegetable and animal oils
Name moisturisers and what they do?
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
If emollients and moisturisers dont work to treat scaling and crusting what is the next step?
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)
