Derm 10 - scaling Flashcards
causes of scaling
Alteration in
- Epidermal turnover times
> Almost any inflammatory insult increases epidermal turnover time
- maturation process
- desquamation
- TEWL (trans-epidermal water loss)
scaling skin conditions presentation
- may be an incidental finding
- dry
- waxy
- scaly
- malodorous
- variable pruritus - etiology dependent
> parasites, xerosis (dry skin), or a secondary microbial dermatitis > pruritus
seborrhea
excessive discharge of sebum from the sebaceous glands.
cornification definition
Cornification encompasses all the processes that lead to the formation of the stratum corneum. This includes the formation of the lipid-rich intercellular material.
Disorders of cornification causes
- defective cornification process
- excessive proliferation and/or desquamation
- abnormal apocrine or sebaceous glandular secretions (either in volume or quality)
primary vs seconday scaling disorders definition
Scaling disorders in dogs can be primary (usually hereditary) or secondary (acquired)
how are localized scaling disorders best diagnosed?
Localized disorders are best diagnosed
by clinical appearance, ruling out differentials and biopsy.
Localized cornification disorders
- Nasal hyperkeratosis of the Labrador retriever
- Nasodigital hyperkeratosis
- Ear margin dermatosis
- Feline Chin Acne
Nasal hyperkeratosis of the Labrador retriever:
- transmission / origin
- timing of lesions, who is affected
- appearance
- autosomal recessive inherited condition that is restricted to the nasal planum
- lesions are noted at an early age, usually between 6 months and a year of age
- Affected dogs can be black, yellow or chocolate
- Dorsal aspect of the nasal planum is usually affected and appears as an accumulation of rough keratin. The footpads may be affected as well.
- Occasionally, erosions and depigmentation will be present
Nasal hyperkeratosis of the Labrador retriever Tx
- Topical application of propylene glycol
feline chin acne
- how common?
- Ddx?
- Tx?
- Common
- Rule out – Demodex; ringworm, contact sensitivity, Eosinophilic granuloma, Xanthoma (rare)
- Treatment options chlorhexidine skin cleanser, sulfur/salicylic acid washes, systemic antibiotics if needed. More severe cases may need to be treated with mupirocin
Nasodigital hyperkeratosis
- breeds affected
- Tx
- Most commonly in Cocker and English Springer Spaniels although any breed can be affected
- Moistening the affected area followed with petrolatum jelly application or propylene glycol treatment may help
- Secondary infections may occur and should be treated appropriately
- More severely affected animals may benefit from topical application of an ointment containing salicylic acid and urea (e.g. Kerasal), 50%-75% propylene glycol, 0.025 or 0.01% tretinoin gel (Retin-A) or tazarotene (retinoid) (reminder, retinoids are highly teratogenic)
Ear margin dermatosis
- how common, what is affected
- breeds?
- appearance
- Tx
- Uncommon condition that only affects the distal pinnal margins
- It occurs primarily in Dachshunds, but other breeds may be affected as well
- Greasy plugs adhere tightly to the pinnal margin and alopecia develops with time
- Severe cases may lead to ulceration and necrosis, like that seen in cases of vasculopathy, frostbite, cold agglutinin disease and lupus
- Treatment includes periodic use of antiseborrheic shampoos such as sulfur-salicylic acid or benzoyl peroxide containing products.
- Severely inflamed cases may benefit from steroid treatments; topical glucocorticoid such as 0.5%-1% hydrocortisone may reduce inflammation.
secondary disorders of cornification presentation?
- Secondary cornification disorders may have a varied presentation, depending on the underlying etiology
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Dull (or waxy) coat with various combinations of
◦ Alopecia
◦ Scaling
◦ Crusting
◦ Collarettes
◦ Excoriations secondary to self-trauma.
When the patient first presents with a scaling dermatosis, it is important to rule out:
- Must rule out secondary causes before pursuing
diagnosis and treatment of primary disorders ofcornification - eg. parasitic cause such as fleas, Cheyletiella, demodex and scabies
secondary cornification disorders Ddx
Parasites
Fleas
Cheyletiella
Demodex
Scabies
working up cornification disorders - step 1
- minimum data base
Minimum Data Base:
Flea combing
Skin scrapings
Acetate tape tests
Parasiticide therapeutic trial
fecal exams
Fungal culture (Wood’s lamp? PCR? )
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- Cytology! Microbial dermatitis is common
- Bacterial culture and susceptibility testing?
> Patients with evidence of a microbial dermatitis
should be treated before considering additional
diagnostic tests for the scaling dermatosis -
minimum of 3 weeks, until complete resolution
working up cornification disorders - step 2
If there is no clinical or cytological evidence of a microbial dermatitis, the next step is to determine if the patient is pruritic
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Yes?
- a food trial and a parasiticide response trial is indicated. If the pruritus persists after 2 months of treatment, environmental allergies should be considered a likely etiology
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No?
- other underlying etiologies should be considered, and appropriate diagnostic tests should be performed.
Working up cornification disorders in the non-pruritic patient: step 3
- conditions predisposing to scaling disorders include:
- Endocrinopathy
> hypothyroidism (fT4, cTSH, TGAA)
> hyperadrenocorticism (LDDST, ultrasound)
> sex hormone imbalance (eg. sertoli cell tumor)
<><> - Allergic: dermatologic adverse food reaction (food allergy), atopic dermatitis
<><> - Management deficiencies: low environmental humidity, inappropriate topical therapy or frequency, nutritionally inadequate diet (especially if high in phytates and fiber, low in fatty acids)
<><> - Metabolic disease (especially liver disease: serum biochemistries, CBC, U/A, possible ultrasound)
<><> - Immune-mediated disease: pemphigus foliaceus, systemic lupus erythematosus, adverse drug reaction eg. destructive mural folliculitis (cytology, skin biopsy)
<><> - Neoplasia: Cutaneous epitheliotropic lymphoma)
<><> - Xerosis (dry skin)
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If all the above is normal or negative, a primary disorder of cornification should be considered. Supportive information is obtained by skin biopsy and response to therapy as well as history and clinical findings
cornification disorders work up, step 4: If steps 1-3 are negative / normal
- what do we do?
If all the above is normal or negative, a primary disorder of cornification should be considered.
- Skin biopsy sent to dermatohistopathologist
> Supportive information is obtained by skin biopsy and response to therapy as well as history and clinical findings
