Scaling & Hyperkeratosis Flashcards
Scale v. Crust
Scale: accumulation of loose statrum corneum fragments
Fragments: stratum corneum + fibrin + inflammatory cells + RB
Primary versus Secondary Cornification Disorders?
Primary: genetic abnormalities (palliative tx; non-curable)
Secondary - MAJORITY: abnormalities due to underlying disease
1º: ichthyosis, primary seborrhea
2º: sebaceous adenitis, zinc-responsive dermatosis, malassezia dermatitis, cutaneous lymphoma
Notoedres cati causes what?
A skin mite that causes mange disease in cats
A young golden retriever presents for non-pruritic, large, white-grey scales. Most noticeably, they are present on its ventrum.
- What is your top differential and its pathogenesis?
- How will you diagnose and treat?
Canine Ichthyosis - 1º cornification
- pathogenesis = malformation of intercellular lipid -> malformation of stratum corneum
- dx = skin biopsy
- tx = symptomatic therapy with goal of reducing degree of condition
An 8-month-old American Cocker Spaniel presents for generalized excessive scaling of skin, but more severe and excessive greasiness around the eyes, mouth, pinnae and in skin folds. During your physical exam, you also find the dog has otitis externa.
- What is your top differential? What is its pathogenesis?
- How will you diagnose and treat this condition?
Canine Primary Seborrhea - 1º cornification
- Pathogenesis: increase in epidermal turnover rate (7 instead of 21 days)
- DX= early onset, breed predisposition. Lesions developed BEFORE pruritus.
- TX = control scaling + 2º infection + epidermal turnover rate w/ VitA or retinoids
Biopsy is NON-diagnostic
American cocker spaniel, English springer spaniel or their crosses, West Highland white terrier
Pathogenesis of Sebaceous adenitis? What breed is predisposed?
Destruction of the sebaceous glands by CD8+ cells’ release of cytotoxins - an autoimmune scaling disorder
- standard poodles
Functions of sebum:
Glossy sheen, keeps skin/hair soft and pliable
Permeability barrier
Retain moisture
Chemical barrier from pathogens
For short-coated breeds with Sebaceous Adentitis, what lesions do you expect to see? What is an important differential?
- Multifocal annular areas of scales & alopecia
- Moth-eaten appearance -> ddx = Bacterial Folliculitis
For long-coated breeds with Sebaceous Adentitis, what lesions do you expect to see?
loss of curl (poodles), excessive scaling / follicular casts; dull hair coat; matting/clumping of hair with partial alopecia
Where to biopsy for sebaceous adenitis? What is the treatment?
- Biopsy from lesions with abundant scaling & follicular cast
- Tx: response is variable and life-long. Goals = control scaling + cyclosporine
Type I v. Type II Zinc-responsive dermatosis
A 2-year-old dog presents for thick, tightly adherent scales on the face and pressure points of the limbs.
- What is your top differential? Others?
- How will you diagnose + treat?
Zinc-Responsive Dermatosis Type I (2º cause of cornification)
- differential = pemphigus foliaceus
- DX = skin biopsy (select where abundant, thick adherent scales/hyperkeratotic lesions)
- TX = zinc supplementation + properly balanced diet
What yeast is a commensal yeast of canine & feline skin? How does this yeast cause dermatitis?
Malassezia pachydermatis -> underlying inflammatory condition that favors overgrowth of the yeast!
A dog presents for pruritis, alopecia and excessive scaling, and the owner reports that their dog smells rancid. You suspect Malassezia dermatitis.
- What are your top differentials for what could be the underlying cause?
- How will you diagnose and treat?
Differentials for underlying causes: Allergic dermatitis / allergic otitis, or intertrigo (facial and vuvlar folds)
- DX = cytology (number of yeast does NOT correlate to severity!)
- TX = based on whether infection is localized (otitis externa = ear ointment like Posatex) or generalized (systemic + topical antifungals) -> treat underlying cause!
What lesions to biopsy for diagnosis of cutaneous lymphoma (2º cause of cornification disorder)?
- Depigmented, erythematous lesions
- Plaques or nodules
- NEVER biopsy ulcerated lesion!
- grave prognosis! 6-9 months even with tx
Prognosis for Cutaneous lymphoma?
