SAD - Chapter 12 - Congenital Keratinization Defects Flashcards
An autosomal dominant mutation in what gene(s) of Rhodesian or Thai ridgebacks result(s) in formation of a dermoid sinus?
fibroblast growth factors (FGF3, FGF4, FGF19)
T/F: Animals with follicular parakeratosis have normal nasal planums and footpads.
TRUE
What are the clinical features of urticaria pigmentosa?
macular and/or crusted papular rash on head and neck, +/- pruritus, +/- hyperpigmentation
What is the pigmentary abnormality with color dilution alopecia?
irregularities in melanin transfer and storage – mature (stage IV) melanosomes are stored irregularly in hairs and epidermal keratinocytes and vacuolization of melanocytes in some hair bulbs
Darier disease is due to mutations in genes that encode what molecules?
calcium pumps
What are the clinical features of dermatomyositis?
skin lesions in areas of mechanical trauma (face, periocular, muzzle, tips of ears, carpal/tarsal region, digits, tip of the tail, onychorrhexis): alopecia, erythema, scale, crust, ulceration
Cats with a blue or cream-colored coat carry what dilution gene?
Maltese dilution gene
An autosomal recessive ectodermal dysplasia-skin fragility syndrome of Chesapeak Bay retrievers has been shown to be due to what defects?
reduced number of partially formed desmosomes; due to lack of plakophilin-1 and anomalies in desmoplakin and keratins 10 & 14
___ is longitudinal splitting of the distal end of a hair.
trichoptilosis
___ is a rare disorder of young intact male Kerry blue terriers where affected dogs have multiple, hard, brittle follicular spicules.
Spiculosis
In addition to hair loss, animals with ectodermal dysplasia have abnormalities in what other organ systems?
dentition and glandular formation/function (epitrichial and atrichial sweat, sebaceous, lacrimal, tracheal and bronchial)
An autosomal recessive primary seborrhea has been reported in what breed ofr cats?
Persians
Dystrophic epidermolysis bullosa results from decreased expression of what protein? Due to a defect in what gene?
collagen VII; mutation in COL7A1 gene
What can worsen the skin lesions of dermatomyositis?
trauma and solar exposure
What is the skin extensibility index for dogs affected with Ehlers Danlos? Cats?
> 14.5% - dogs, >19% - cats
What are clinical signs of myositis in animals with dermatomyositis?
dysphagia, megaesophagus, high-stepping stiff gait, asymptomatic muscle atrophy
In the German Shorthaired Pointer, ______ is an autosomal recessive trait associated with decreased expression of laminin-332.
junctional epidermolysis bullosa
Familial footpad hyperkeratosis has been described in what breed(s)?
Irish terriers and Dogue de Bordeaux
____ is a neural tube defect resulting from incomplete separation of the skin and neural tube during embryonic development.
Dermoid sinus
T/F: The presence of melanin clumping is diagnostic for color dilution alopecia.
False - indicates action of dilution genes, does not necessarily mean the animal has color dilution alopecia
In the German Shorthaired Pointer, junctional epidermolysis bullosa is an autosomal recessive trait associated with decreased expression of what?
laminin-332 laminin 5)
What are the clinical lesions of canine Darier disease?
alopecia, erythema, scaling –> plaquelike
What is the primary cause of acral mutilation syndrome?
pathologic lesions at the level of the primary sensory neuron, decrease in promeninence of the spinal ganglia and dorsal roots
With epidermolysis bullosa simplex, where does clefting occur?
basal layer of epidermis (most superficial of epidermolysis bullosa types)
Darier disease due to abnormal calcium homeostasis has been reported in what breed(s)?
English setters, Doberman pinscher
Histopathologic changes with lethal acrodermatitis of Bull terriers?
diffuse parakeratotic hyperkeratosis with focal crusting and intraepidermal pustules; superficial epidermis may have laminar pallor
Cutis laxa is due to abnormalities in what structure?
elastic fibers
What is the defect in Ehlers Danlos?
structural changes in collagen – forms twisted ribbons rather than cylindrical fibrils and fibers; procollagen processing defect –> decreased activity of procollagen peptidase and an accumulation of partially processed type I procollagen, decreased collagenase activity
An ulcerative nasal dermatitis has been reported in what breed of cats?
Bengal cats
What are the clinical features of canine cyclic hematopoiesis?
silver-gray hair coat, light-colored nose
Canine cyclic hematopoiesis results from a mutation of the gene encoding what protein?
dog adaptor protein complex 3 (APB3)
Canine darier disease has been repoted in English setters due to a depltion of what?
SERCA2-gated stores
What are the histopathologic changes are present with pattern baldness?
decrease in size (miniaturization) of the hair follicles and hair shafts with normal adnexal structures; follicles are shorter and thinner, hae smaller hair bulbs, and produce fine hair shafts
With junctional epidermolysis bullosa, where does clefting occur?
lamina lucida of the dermoepidermal basement membrane
What is the defect in canine Darier disease and why does it result in clinical disease?
mutation in gene encoding calcium pumps, impairs desmosomal function or epidermal differentiation –> epidermis cannot withstand trauma and vesiculobullous lesions develop in response to friction or infecton
What are the histopathologic features of Schnauzer comedo syndrome?
keratinous plug blocking the hair follicle and sebaceous gland –> cystic cavity is formed by stretched follicular epithelium and filled with keratin and sebum
T/F: Mexiacn hairless dogs have a shorter lifespan than their haired relatives.
True - unclear if there is a familial immunoincompetence linked to hairlessness
Which typically occurs first with dermatomyositis: skin or muscle lesions?
skin - myositis typically occurs months after the skin lesions
Canine cyclic hematopoiesis has what mode of inheritance?
lethal autosomal recessive
T/F: Biopsy is necessary to confirm a diagnosis of idiopathic facial dermatitis of Persian and Himalayan cats.
False - is often nondiagnostic
Chediak-Higashi syndrome has what mode of inheritance?
autosomal recessive
What are the histopathologic features of follicular lipidosis?
severe swelling of the matrix cells of anagen hair follicles due to accumulation of lipid within the cell’s cytoplasm
What are the histopathologic features of dermatomyositis?
hydropic degeneration of surface and follicular basal cells; apoptotic basal cells (Civatte bodies); perivascular to interstitial dermatitis; follicular atrophy and perifollicular fibrosis; vasculitis
What is the presenting complaint with follicular lipidosis?
hair loss in the mahogany points of the face (in Rottweilers)
What are the clinical features of psoriasiform-lichenoid dermatosis?
erythematous, lichenoid papules and plauqes on pinnae, external ear canal, inguinal region –> become hyperkeratotic
Psoriasiform-lichenoid dermatosis is reported in what breed?
English Springer Spaniels
Why are animals with ectodermal dysplasia more prone to respiratory infections?
decreased glandular secretions and impaired thermoregulation
Vitamin D analogs alter epidermal proliferation and terminal differentiation and may be useful for treatment of primary seborrhea. What needs to be monitored with calcitriol therapy? Why?
electrolyte levels, esp. calcium, because calcitriol can decrease parathyroid hormone
What stain is used to identify collagen disorders?
Masson trichrome stain
What are the clinical lesions of junctional epidermolysis bullosa?
erosive to ulcerative lesions over bony prominences of the face, pinna, pressure points on the limbs or footpads, oral cavity
What is the most common cutaneous manifestation of mastocytosis?
urticaria pigmentosa
T/F: Steroids are beneficial in the treatment of canine darier disease.
Unclear – in humans has clear benefit but not reported in dogs
Histopathologic features of canine darier disease?
acanthosis w/ orthokeratotic and parakeratotic hyperkeratosis and marked, diffuse acantholysis of lower and middle portions of epidermis and follicular outer root sheath
Histopathologic features of color dilution alopecia?
sebaceous melanosis, melanin clumping in epidermal and follicular basal cells and hair matrix cells, macromelanosomes in hair shafts, peribulbar melanophages, follicular hyperkeratosis, fractured hair shafts, free clumps of melanin
Acral mutilation syndrome has been reported in what breeds?
German shorthaired pointers, English springer spaniel, English pointer dogs, French spaniels, miniature pinscher
What histopathologic changes are present with black hair follicular dysplasia?
clumped melanin in epidermal and follicular basal cells and hair matrix cells; macromelanosomes visible within hair shafts; follicles are irregular, dilated, and filled with keratin, fragments of hair shafts, large clumps of free melanin
What are the histopathologic features of psoriasiform-lichenoid dermatosis?
superficial perivascular to interstitial dermatitis with psoriasiform epidermal hyperplasia and areas of lichenoid interface dermatitis, intraepidermal microabscesses (containing eos and neuts), Munro microabscesses
Follicular lipidosis has been reported in what breed?
Rottweiler
What changes are present on skin biopsy with Ehlers Danlos?
changes may not be present in cats; collagen fibers may be more eosinophilic than normal and blurred in appearance, fragmented, shortened and disoriented; form irregularly sized bundles
Darier disease has an autosomal (dominant/recessive) mode of inheritance?
dominant
What changes are present on skin biopsy with ectodermal dysplasia?
hair follicles, arrector pili muscles, sebaceous glands, and epitrichial sweat glands are reduced in number, hypoplastic or absent
_____ is an acquired defect in which external insults damage the cuticle and weaken the hair shaft.
trichorrhexis nodosa
Where does the split occur with dystrophic epidermolysis bullosa?
sub-basilar dermoepidermal separation (beneath the lamina densa)
Dermoid sinus has been reported in what breed of cats?
Burmese
