Scaling And Hyperkeratosis Flashcards
Scale
Or flakes is the build up of loose fragments (clusters) of the
stratum corneum
Due to disorder of:
-Maturation of the epidermis
- Glandular (sebaceous) secretion
Crust
Composed of stratum corneum, fibrin, inflammatory & red blood cells - usually thicker than a scale
Cornification
Process of stratum basale cells, requires atp, zinc or lack of can affect this process
Epidermal turnover rate
20-25 days
Requires delicate balance between cell death & renewal
Hyperkeratosis
Abnormal thickening of stratum corneum
Attempting to heal from insults or damage
Basal cells are stimulated to produce more daughter cells
Stratum corneum is replenished faster than it is desquamated
Can be part of the aging process - senile Hyperkeratosis on nose and footpads
Primary Cornification disorders
Genetic abnormalities in cornification process
1. Ichthyosis
2. Canine primary seborrhea
Can be managed but not cured
Secondary cornification disorders
Abnormalities caused by underlying disease
1. Scabies
2. Allergic dermatitis
3. Metabolic disease
4. Endocrine disease
Scaling and hyperkeratosis
Majority (>90%) of scaling/HK is caused by underlying disease
Due to inflammation that stimulates epidermal turnover
Important to investigate & treat the underlying disease
Canine Ichthyosis
Breed disposition - golden retriever, doodle, bulldog, jack Russell, Great Dane
Cause of canine Ichthyosis
Genetic abnormality in formation of stratum corneum due to malformation of intercellular lipid
Onsets at younger ages
Lesions of canine Ichthyosis
Large white to grey scales, most noticeable on ventrum but can be generalized
Pruritus is usually NOT seen UNLESS there is 2nd infection
DX of Ichthyosis
Skin biopsy, genetic testing - clinical signs and flakes
TX of Ichthyosis
TX is NOT curative - only targets symptoms and improves skin barrier function
Topical and systemic therapy
Topical
- kertolytic shampoo - exfoliating shampoo (SA acid/sulfur)
- moisturizers & Antimicrobials shampoo - chlorhexidine
- oil based spot treatment
Systemic - retinoids
Canine primary seborrhea
Most common in cocker spaniels, springer spaniels and X, westies and terriers
Cause of primary seborrhea
Increase in epidermal turnover rate - 7 days instead of 21d
Due to increase in BM cell division
Leads to abnormal cornification and desquamation
Can also affect basal cell lining ear canal and gland function
Clinical features of primary seborrhea - skin lesion
Skin lesions present <1 y and progress in severity w age
- excessive scaling - generalized
- severe around mouth/eyes, pinnae, skin folds w excessive greasiness
- 2nd infection is common - yeast/bacteria
- follicular cast is also common
Clinical features of primary seborrhea - otitis externa
Due to increased scaling in ear canal and cerumen +/- secondary infection
Seborrhea sicca vs oleosa
Sicca - flakey skin appearence
Oleosa - greasy skin appearence
DX of primary seborrhea
EARLY onset, breeds
Skin lesions develop (usually) BEFORE pruruitis
Skin biopsy - non diagnostic bc there’s other causes of 2nd seborrhea w similar histopath - aka not specific
Tx of primary seborrhea
NOT curative
1. Control scaling - antiseborrheic shampoo - sulfur, SA acid
2. Control 2nd infection - topical or systemic meds
3. “Control” /attempt epidermal turnover rate w Vit A or retinoids
Sebaceous adenitis
Common in poodles, akitas, samoyeds, vizslas, havanese
Caused by destruction of sebaceous glands by cytotoxic T-lymphocytes
Function of sebaceous glands
Holocrine glands that open through a
duct into the infundibulum. Secrete oily emulsion called sebum that spreads over the hair shaft and skin
Functions of sebum:
-Glossy sheen, keeps skin/hair soft and pliable
-Permeability barrier
-Retain moisture
-Chemical barrier from pathogens
Sebaceous adenitis in long coat
Poodle, Akita, Samoyed
Darker or lighter hair color
Poodles: loss of curl
Excessive scaling or follicular cast
Poor and dull hair coats
Matting /clumping, partial alopecia
Clinical signs of sebaceous adenitis in short coat
Viszslas, dachshund
Multi focal annular areas of scaling and alopecia
Can progress/enlarge & turn polycyclic or coalesce to a large lesion
Moth eaten appearence
Key clinical features of sebaceous adenitis
Lesions first present dorsally head to lumbar and Dorso-ventral progression
Lesions then progress to generalized distribution
Pruritus varies from not present to severe
2nd infection can occur and contribute to or worsen puritus
DX of sebaceous adenitis
Skin biopsy - select lesions w abundant scaling/follicular cast
TX of sebaceous adenitis
Control scaling - antiseborrheic shampoo
Cyclosporine
Not all dogs respond to treatment and require life long Tx
Zinc responsive dermatosis
RARE chronic cornification disorder that responds to zinc supplementation. Two types
type I ZRD
Caused by a genetic defect in zinc absorption leading to impaired desquamation
Breeds: Siberian husky, Alaskan malamutes can occur in others
Type II ZRD
Affects puppies fed w zinc deficient diet
RARE today due to commercial diets
Clinical features of ZRD type I
Young adult onset (1-3)
Tightly adherent THICK scales, Hyperkeratotic plaques
Crusting lesions can develop
Distribution of ZRD type I
Face - periorbital, perioral, pinnae
Pressure points on limbs (elbows, hocks) footpads
DX of ZRD Type I
Skin biopsy - select lesions with abundant thick adherent scales or hyperkeratotic lesions
TX for ZRD type I
- Premium dog food
- Zinc supplementation
- Low dose prednisone may improve response
Malassezia dermatitis
Malassazia pachydermatis is NF on cats and dog skin
Common areas: lip commissures, ext ear canal, interdigital skin and perineum (moist skin folds)
Clinical features of malassezia dermatitis
Excessive scaling ONE OF many skin lesions caused. Also includes:
- erythema
- self induced alopecia (due to pruritus)
- hyperpigmentation and lichenification
- greasiness (seborrhea oleosa)
- rancid or foul smelling skin
Important clinical features of malassezia dermaitis
Smell is NOT specific to malassezia dermaitis - smells can develop due to bacterial or yeast infection
Underlying diseases that favor malassezia overgrwoth
- Allergic dermatitis or allergic otitis
- Intertrigo (esp in facial and vulvar folds)
DX of malassezia dermatitis
Skin CYTOLOGY
Yeasts on cytology DO NOT correlate w disease severity
Need to correlate clinical signs and skin lesions with cytology
TX of malassezia dermaitis
- Location or otitis externa - topical antifungal shampoo/ointment/cream
- Generalized - systemic antifungal (azole) + topical
- Investigate underlying cause that could predispose and treat accordingly
Cutaneous lymphoma
Lots of names and lesions
Rare in cats and dogs
Dogs presentation is highly variable
Clinical features of cutaneous lymphoma
Periorbital Depigmentation, erosion, crust
Exfoliative erythroderma
SKIN BIOPSY IS A MUST - but which lesion ??
DX of cutaneous lymphoma
Take biopsy samples from
- depigmented lesions
- lesions w loss of architecture
- erythematous & scaly lesions
- plaques or nodules
NEVER biopsy an entirely ulcerative lesion
TX of cutaneous lymphoma
GRAVE Px
Treatment is palliative
