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Genodermatoses
structure and function
39
Veterinary Medicine
Professional
10/16/2021

Additional Veterinary Medicine Flashcards

 


 

Cards

Term

Genetic skin disease in dogs and cats:

Definition

-Epidermis (ichthyosis)

-Basement membrane zone (lupus)

-Dermis (Ehler’s Danlos, mucinosis)
-Hair follicle (congenital alopecia

Term

Normal vs. abnormal Cornification

Definition

-modified apoptosis

-70% water loss

-cell interior-keratin fibrils

-cell membrane becomes a cornified envelope

-lipid bilayers

-Statum corneum abnormalities-à altered barrier fxn (loss of integrity, water loss, inflammation and pathogen/allergen entry occurs

Term

-Damaged barrier

Definition

-induces clinical scaling to make more cells/lipid to try to make barrier hydrophobic and repair it which is manifested as clinical scaling

-Primary DOC-anomalies in genes that encode structural proteins or enzymes involved in lipid formation or lipid transport (few tx options, managed but NOT cured)

-Secondary DOC (Vet med term only!)- more than 80% of scaling disorders arise from secondary causes (scabies, adverse food rxn, metabolic dz and endocrinopathy, etc)

Term
ARCI (Autosomal recessive congenital ichthyosis)- name breeds affected
Definition

-Golden retriever-PNPLA-1- variable onset age- lipid metabolism defect- generalized white powdery scale, abdominal pigmentation ventrum

-American bulldog-NIPAL-4- scaling from birth-lipid processing enzyme defect/metabolism-v- generalized scaling, red abdomen but not lichenified, pruritic due to Malassezia overgrowth

-JRT (TGM1)- severe cornification defect-lose a lot of water through skin, drink more water and Malassezia overgrowth
-Cavalier king Charles spaniel

-may occur in any breed

Term

Ichthyosis tx

Definition

-no treatment

-soak and slather

-address secondary infections (esp American bulldogs)

Term

 

Interface term

Definition

-unique hereditary cutaneous lupus in dogs

-affects jxn between epidermis and basement membrane zone and involves basal cell layer and usually immune-mediated

-In humans: 3 categories of lupus (acute, subacute, chronic)

-basal cell vacuolar degeneration +/-apoptosis

+/- mononuclear cell infiltration at dermoepidermal jxn

-melanin that normally resides in keratinocytes falls into dermis (pigmentary incontinence)

-canine cutaneous lupus erythematosus (2 categories: Hereditary and Acquired)

Term

Hereditary Canine Cutaneous Lupus erythematosus

Definition

-Exfoliative cutaneous lupus erythematosus seen in German short-haired pointer, Magyar vizslas

-Vesciular lupus erythematosus seen in Shelties, Collie and Border Collie

Term

 

-Acquired canine cutaneous lupus erythematosus

Definition

-Localized and generalized discoid lupus

-Mucocutaneous lupus

-Systemic lupus erythematosus

Term

Exfoliative cutaneous lupus erythematosus

Definition

-seen in German short-haired pointer

-affects muzzle, trunk, scrotum, extremities

-scaling, erythema, alopecia, depigmentation, erosions and ulcers

-crouched stance of back

-generalized lymphadenopathy

-shifting leg lameness (arthralgia)

-mild thrombocytopenia/lymphopenia

-hyperproteinemia

-infertility

-FNA L.N.- hyperplasia and plasmacytosis with medullary histiocytosis

-ulcerated scrotums

-Missense variant affecting C-terminal tail of UNC93B1

-50% of dogs euthanized

-managed with corticosteroids, azathioprine and HYDROXYCHLORINE (anti-malarial drug) help slow progression

Term
Skin lesions-non-specific CCLE
Definition

-secondary otitis

-superficial pyoderma

-acral pruritic nodules

Term

VCLE breed affected

Definition

-hereditary in Collie, Sheltie and border collie

-Vesicular lupus (aka ulcerative dermatosis)

-Interface rxn with apoptosis of basal keratinocytes with clefting at basement membrane of epidermis and outer root sheath of hair follicle

-drug rxn (EM) may look similar

-adult-onset disease

-calcineurin inhibitors help (oral cyclosporine and topical Tacrolimus)

Familial Dermatomyositis

- “ischemic dermatopathy”

-Juvenile collies and Shelties

-hair loss on muzzle area with scarring alopecia with hypo/hyperpigmentation with erosions

-Skin biopsy needed to differentiate from demodicosis, dermatomyositis, Staph folliculitis

-vascular disease causes ischemic change to skin and causes hair follicle/sebaceous gland atrophy (apocrine glands are spared)

-autosomal dominant and affects young dogs

-Alopecia, scaling and atrophy

-Periocular, muzzle, pinnal margins

-Muscle disease variable

-immune mediated

-vascular injury causes slow ischemic change to skin

Term

Ischemic dermatopathy

Definition

-Histologic diagnosis for group of diseases characterized by inadequate blood and nutrient supply to skin

-common following Rabies vaccine rxn

-Types: 1) Familial Dermatomyositis 2) Dermatomyositis-like 3) Rabies vaccine induced vasculitis with alopecia 4) Vaccine associated ischemic dermatopathy 5) Idiopathic ischemic dermatopathy

Term

Treatment of Ischemic dermatopathy

Definition

-Pentoxifylline (Methylxanthine derivative)-Vasculopathic disorders- increased microvascular blood flowà increased microvascular blood flow---Increased deformability of rbcs, decreased platelet adhesion, anti-inflammatory properties

-Vitamin E

-Sunscreen

-Glucocorticoids

Term

Localized vaccine reaction

Definition

-focal area of hair loss and hyperpigmented

-may be severe and lead to nail loss

-nodules, edema in panniculis with adjuvant

-smudging of collagen in dermis, fading follicles

Term

-Generalized ischemic dermatopathy

Definition

-vasculitis affects ears, muzzle and nasal planum atrophies

-usually close association to vaccine being given

-smaller dogs and older dogs less likely to have vaccine association (idiopathic)

-Poodles more likely to have vaccine association

-immunomodulatory drug management

Term

Dermis Components and Function

Definition

-Collagen, elastin, proteoglycans

-resident perivascular inflammatory cells (dendritic cells, lymphocytes, mast cells)

Term

 

Ehlers-Danlos

Definition

-Inherited disorders of connective tissue

-Wide phenotype-hyperextensible skin to aortic rupture

-Dogs, cats, calves, sheep, cattle

-skin hyperextensibility index increased

-histopathology reveals collagen fibers that are fragmented/disarray and varied in length with large spaces of amorphous eosinophilic matrix

-Multiple genetic variants identified: TNXB, ADAMTS2, COL5A1

Term

Feline Ehlers Danlos

Definition

-Cutaneous asthenia

-Himalyan, Burmese

-Skin hyperelasticity

-Burmese cats develop necrotic eschars

-Normal wound healing

-Not typically lethal

-Collagen changes may be too subtle for light microscopy

-need to know difference and distinguish from acquired skin fragility (seen in older cat due to severe loss of dermal collagen- hair follicles in telogen, due to pituitary tumor or any tumor that leads to excess cortisol or chronic glucocorticoid therapy)

Term

Feline acquired skin fragility

Definition

-NOT congenital disease, NOT Ehlers Danlos

-Older cats

-Thin skin that tears easily, atrophic scars

-Spontaneous or iatrogenic hyperglucocorticism; diabetes mellitus, hepatic lipidosis, drugs

-profound atrophy of dermal collagen fibers

-prognosis poor

Term

 

Cutaneous Mucinosis

Definition

-Hyaluronic acid (Alcian blue stain)

-Shar pei mucinosis due to increased hyaluronan production

-secondary pyoderma

-excess mucin, vesicles-àrupture

Term

 

Congenital Epidermolysis Bullosa

Definition

-(simplex, junctional, dystrophic)

-positive Nikolsky sign

-Congenital

-cannot treat

Acquired Epidermolysis bullosa

-Mucous membrane pemphigoid

-Epidermolysis bullosa acquisita

-can treat with immunosuppressive drugs

Term

 

Eurasier dogs mutation

Definition

-sloughing pawpads, inguinal region prepuce

-oral cavity ulcers (positive Nikolsky sign)

-epidermis cannot adhere dermis

-stain adherent bottom of cleft

-Plectin mutation-keratin tonofiliments connected to hemidesmosomes (PLEC1 mutation)

Term

 

Junctional EB, Herlitz (horses)

Definition

-Aplasia cutis congenita

-pull hooves off skin, clean clefts

-described in Belgian horses

Term
What is the gene mutation for Goldens with icthyosis?
Definition
PNPLA1
Term
What is the gene mutation for American Bulldogs with ichthyosis?
Definition
NIPAL4
Term
What is the gene mutation for ichthyosis in Jack Russell terriers?
Definition
Transglutaminase 1
Term
Which breed of dog is the only reported breed with epidermolytic ichthyosis?
Definition
Norfolk terrier
Term
What is the genetic mutation for ichthyosis in the Norfolk terrier?
Definition
Keratin 10
Term
What breed of cat has been reported to have a congenital ichthyosis?
Definition
Abyssinians
Term
What white blood cell type is affected in Collies with gray collie syndrome?
Definition
Neutrophils (also called cyclic neutropenia)
Term
Congenital pinnal hyperkeratosis has been recognized in what breed?
Definition
French bulldogs
Term
What treatment was shown to be effective in a French bulldog with congenital pinnal hyperkeratosis?
Definition
Vitamin A controlled the lesions in one month
Term
What breed of dog has a described congenital ectodermal dysplasia-skin fragility syndrome?
Definition
Chesapeake Bay retreivers
Term
A mutation in which important adhesion molecule causes ectodermal dysplasia in Chessies?
Definition
Mutation in plankophilin-1

Plankophilin binds to desmocollin/desmoglein to reinforce strength of the desmosome
Term
What breed of dog has the inherited connective tissue disorder Musladin-Lueke syndrome been described in?
Definition
Beagles
Term
MLS syndrome in Beagles is characterized by stiff gait/tip-toe stance (joint capsule fibrosis), abnormal facial features and a unique cartilage ear fold. What connective tissue abnormality seems to be the cause of these signs?
Definition
A transition of fibroblasts (with excessive TGFb activity- the mutation affects normal TGFb binding sites, so there is too much around)

This leads to a transition of fibroblasts to myofibroblasts and their associated issues (lots of contractility!)
Term
What is the mode of inheritance for DMS in Collies and Shelties?
Definition
It is a complex three locus disorder with complicated inheritance. The combination of specific alleles at each locus confers a different level of risk for the disease.

Genetic testing is available. The recent genes identified are PAN2 and MAPK3K7CL. The other strong association is with specific DLA/MCH haplotypes (this is homozygous in most dogs in these breeds)
Term
A mutation in what enzyme is responsible for excessive skin and periodic fever in Shar pei?
Definition
HAS2 (hyaluron synthase 2)
Term
Mutations in what gene are associated with dilute coat color?
Definition
MLPH (melanophilin)
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