Crusting disease Flashcards
What is crust?
What does crust occur?
Crust = dried exudate, containing blood/serum/scales/pus (colloquially a ‘scab’)
- Primary lesion - occasionally
- Secondary lesion - usually, e.g. to
- scaling
- pustular
- ulcerative
What is the most common cause of crust in the dog?
Superficial pyoderma is the most common cause of crusts in dog!
What is your top differnetial for this dog:
Middle-aged Labrador?
Pruritic crusting on ventral abdominal/perivulval skin. No pruritus or skin disease prior to appearance of crusts. Weight gain, lethargy.
Hypothyroid
What are the steps in investigating crust?
First step usually
* Rule out ectoparasites
* routine tests (e.g. skin scrapes, combing, trichogram) + treatment trial
* Rule out microbial infections
* Bacterial pyoderma – cytology – of primary lesion, if possible, otherwise impression smear from skin under crust
* Dermatophytosis (esp cat) - Wood’s lamp, dermatophyte culture
Then further investigations if lesions remain, especially biopsy
* NB biopsy most likely to be diagnostic if secondary infections cleared first
* **Don’t dislodge crust! **- trim hair with scissors but otherwise no prep
* Request special stains, esp re microorganisms
What are the clincial signs, signalment and cytology of Pemphigus foliaceus in the dog ?
Clinical signs
* Pustules different to pyoderma!
* Often larger and with erythematous margins
* Distribution – often includes face/pinnae/footpads
* Lesions bilaterally symmetrical
- Crusting (honey coloured)
- no pruritus
Signalment:
* Middle aged to older dogs (but can occur at any age)
* Akita, Chows, Cocker spaniels, Dachshunds, Labradors, English bulldog & Shetland sheepdog
Cytology:
* No evidence of microbial infection on cytology of skin under the crust
* Acantholytic keratinocytes(large ‘fried-egg’ cells, sometimes in rafts) + neutrophils
What is seen there on this cytology? what is your top d/d?
Acantholytic keratinocytes (large ‘fried-egg’ cells, sometimes in rafts) + neutrophils
- very suggestive of pemphigus foliaceus – biopsy needed to confirm
What is the pathogenesis of pemphigus foliaceus in the dog?
- Auto-immune (mainly IgG) response to desmosomal proteins, especially desmocollin 1
- Mainly expressed in superficial layers of epidermis so lesions fairly superficial
- Trigger? Usually idiopathic. Occasionally drugs, ?UV
What is the treatment and prognosis for pemphigus foliaceus in the dog?
Induction
* Immunosuppressive doses of systemic GCC, usually prednisolone – rapid action
* +/- topical GCC
* Treat till most lesions healed and no new lesions for 10 days
Titration - Taper SLOWLY to lowest effective maintenance dose, q48h if possible
**+/- adjunctive immunosuppressive agent **– to help minimise steroid dose, e.g.
* Chlorambucil
* Ciclosporin/ tacrolimus
* Azathioprine
* Mycophenolate mofetil
* NB many slow (e.g. 4 weeks) to take effect, so may give alongside steroids from onset
Prognosis - Often poor due to adverse effects of treatments
What is the differnece in clinical signs of pemphigus foliaceus in the cat?
claw folds affected in 30% cases and skin around nipples (areolar skin)…
What are the treatment and prognosis differences in pemphigus foliaceus in the cat?
- Occasionally oral dexamethasone (off label) in place of prednisolone
- +/- adjunctive treatments
- Chlorambucil (NB NOT AZATHIOPRINE for cats!)
- Ciclosporin, topical steroids
- Monitor fructosamine on steroids?
- Prognosis better than dog
What are the alternative names for Canine juvenile sterile granulomatous dermatitis and lymphadenitis ?
‘juvenile cellulitis’, ‘puppy strangles’
What is Canine juvenile sterile granulomatous dermatitis and lymphadenitis?
What is the signalment?
What are the clincial signs?
- Sterile granulomatous condition affecting face, pinnae, ears and submandibular lymph nodes
- Aetiology unknown – immune dysfunction?
- Breeds – esp Golden/Labrador retrievers, Daxis
- Age – usually puppies, occasionally adults
Clinical signs
* Sterile pustules –> ulcers/draining tracts/crusts/hair loss and cellulitis affecting above areas
* Acute swelling of muzzle, lips, eyelids (d/d angio-oedema)
* Marked submandibular lymphadenopathy
* Rarely nodules at other sites
* +/- otitis externa
* +/- pyrexia, depression, anorexia, joint pain
When diagnosing Canine juvenile sterile granulomatous dermatitis and lymphadenitis, what is involved and what is it vital to do, why?
Signalment, history, clinical signs – very suggestive
Important to rule out other conditions that may cause cellulitis:
* Demodicosis - as treatment is different
* Infections – bacterial pyoderma, dermatophytosis
NB on cytology - pyogranulomatous and apparently sterile inflammation
Biopsy confirmatory – send for histopathology and tissue culture
What is the treatment and prognosis for Canine juvenile sterile granulomatous dermatitis and lymphadenitis ?
Treatment
* Prednisolone (immunosuppressive doses) to resolution (7-14 days?), then taper slowly to withdraw
* +/- other immunosuppressive agents, e.g. ciclosporin
* Warm soaks, topical washes
* Antibiotics not needed unless secondary infection present
Prognosis
* Good if treat early but may scar if treatment delayed may need to treat before histopath results return!
What cats are affected by Squamous cell carcinoma (SCC) / solar dermatitis?
What are the clinical signs?
Affects
* older cats
* usually unpigmented nasal planum, pinna, eyelids
* esp white cats
UV-related – possible link also with papilloma virus infection?
NB may be preceded by actinic (solar) keratosis
* erythematous plaque with erosion/ulceration/crust
* can transform to invasive SCC
Clinical signs
* Usually flat, firm, ulcerated lesions –> tissue destruction
* Often crusted. Often >1 lesion
What is the diagnosis, treatment and prevention of Squamous cell carcinoma (SCC) in cats?
Diagnosis
* Biopsy –> histopathology
* Locally invasive but low metastatic potential
* NB still check chest radiographs/ FNA of drainage LNs before extensive therapy
Treatment depends on site and size of neoplasm.
* Superficial tumours respond well to all therapies
* Infiltrative tumours need aggressive surgery + radiotherapy or adjuvant chemotherapy
* Surgery: including pinnectomy, nasal planectomy
* Laser therapy or cryotherapy (early, shallow lesions)
* Imiquimod cream (early, shallow lesions)
Prevention of new lesions
* Sunblock
* Keep indoors in strong sunlight
* UV light blocking film on windows?
What is the prognosis of canine Squamous cell carcinoma (SCC)?
Prognosis depends on site:
* Nasal planum, legs, scrotum, trunk
* Low metastatic potential
* –> surgery (NB cosmetic considerations)
- Claw bed (subungual) – common!
- More aggressive
What are the characteristics of feline acne?
- Dark waxy scales/crust on chin
- May be primary disorder, but often secondary (e.g. to dermatophytosis, demodicosis)
- Often develop secondary Malassezia, pyoderma and furunculosis
- Rule out demodicosis/dermatophytosis
- Address any secondary microbial infection
- Often maintenance management with topical keratolytic products
What is calcinosis cutis?
What is it due to?
= inappropriate deposition of calcium phosphate in skin/subcutis
–> gritty white deposits –> provoke surrounding inflammation and crust
Usually due to
* Dystrophic calcification - i.e. deposition in injured, degenerating or dead tissue
e.g. HAC!!
Occasionally
* Metastatic calcification - i.e. altered serum levels of calcium/phosphorus
e.g. chronic renal disease
* Idiopathic (e.g. calcinosis circumscripta)
What is the signalment of superficla necrolytic dermatits?
What are the clinical signs?
Signalment - Affects middle-aged/older dogs
**Clinical signs **
* dogs are ill
* Hyperkeratosis of footpads – most cases
* Erythema, ulcers/erosions, crusting, especially
* mucocutaneous areas, muzzle
* distal limbs, hocks, elbows
* +/- secondary infection
* +/- pruritus
How is Superficial necrolytic dermatitis diagnosed?
What is the treatment?
What is the prognosis?
Diagnosis
* Histopathology, supported by relevant changes on haematology/biochemistry
* Imaging of abdomen (particularly US)
* +/- liver biopsy
Treatment
* Dietary supplementation – amino-acids, EFAs, zinc, Vit E (egg yolks)
* Treat secondary infections
* Address u/lying cause if possible
Prognosis often poor
Superficial necrolytic dermatitis lesions are due to keratinocyte death, what is this associated with?
- end-stage liver disease
- pancreatic atrophy/ glucagonomas –> diabetes mellitus
What skin condition do persian cats get?
What is the clinical apperance?
What is the treatment?
What is the prognosis?
Idiopathic facial dermatitis of Persians
- Poorly-understood condition
- Tightly adherent, greasy black scales
- Malassezia dermatitis
- Treatment
- Anti-yeast therapy - itraconazole
- Ciclosporin ± prednisolone (half does of ciclosporin as blood level will be affected by itraconazole)
- Guarded prognosis
A 6yo DLH cat presents with bilaterally symmetrical crusting affecting the pinnae and face, and a caseous claw fold exudate affecting multiple digits.
What is your top differential diagnosis?
Feline pemphigus foliaceus
