SAD - Chapter 12 - Congenital Keratinization Defects

Question 1

An autosomal dominant mutation in what gene(s) of Rhodesian or Thai ridgebacks result(s) in formation of a dermoid sinus?

Answer 1

fibroblast growth factors (FGF3, FGF4, FGF19)

Question 2

T/F: Animals with follicular parakeratosis have normal nasal planums and footpads.

Answer 2

TRUE

Question 3

What are the clinical features of urticaria pigmentosa?

Answer 3

macular and/or crusted papular rash on head and neck, +/- pruritus, +/- hyperpigmentation

Question 4

What is the pigmentary abnormality with color dilution alopecia?

Answer 4

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

Question 5

Darier disease is due to mutations in genes that encode what molecules?

Answer 5

calcium pumps

Question 6

What are the clinical features of dermatomyositis?

Answer 6

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

Question 7

Cats with a blue or cream-colored coat carry what dilution gene?

Answer 7

Maltese dilution gene

Question 8

An autosomal recessive ectodermal dysplasia-skin fragility syndrome of Chesapeak Bay retrievers has been shown to be due to what defects?

Answer 8

reduced number of partially formed desmosomes; due to lack of plakophilin-1 and anomalies in desmoplakin and keratins 10 & 14

Question 9

___ is longitudinal splitting of the distal end of a hair.

Answer 9

trichoptilosis

Question 10

___ is a rare disorder of young intact male Kerry blue terriers where affected dogs have multiple, hard, brittle follicular spicules.

Answer 10

Spiculosis

Question 11

In addition to hair loss, animals with ectodermal dysplasia have abnormalities in what other organ systems?

Answer 11

dentition and glandular formation/function (epitrichial and atrichial sweat, sebaceous, lacrimal, tracheal and bronchial)

Question 12

An autosomal recessive primary seborrhea has been reported in what breed ofr cats?

Answer 12

Persians

Question 13

Dystrophic epidermolysis bullosa results from decreased expression of what protein? Due to a defect in what gene?

Answer 13

collagen VII; mutation in COL7A1 gene

Question 14

What can worsen the skin lesions of dermatomyositis?

Answer 14

trauma and solar exposure

Question 15

What is the skin extensibility index for dogs affected with Ehlers Danlos? Cats?

Answer 15

> 14.5% - dogs, >19% - cats

Question 16

What are clinical signs of myositis in animals with dermatomyositis?

Answer 16

dysphagia, megaesophagus, high-stepping stiff gait, asymptomatic muscle atrophy

Question 17

In the German Shorthaired Pointer, ______ is an autosomal recessive trait associated with decreased expression of laminin-332.

Answer 17

junctional epidermolysis bullosa

Question 18

Familial footpad hyperkeratosis has been described in what breed(s)?

Answer 18

Irish terriers and Dogue de Bordeaux

Question 19

____ is a neural tube defect resulting from incomplete separation of the skin and neural tube during embryonic development.

Answer 19

Dermoid sinus

Question 20

T/F: The presence of melanin clumping is diagnostic for color dilution alopecia.

Answer 20

False - indicates action of dilution genes, does not necessarily mean the animal has color dilution alopecia

Question 21

In the German Shorthaired Pointer, junctional epidermolysis bullosa is an autosomal recessive trait associated with decreased expression of what?

Answer 21

laminin-332 laminin 5)

Question 22

What are the clinical lesions of canine Darier disease?

Answer 22

alopecia, erythema, scaling –> plaquelike

Question 23

What is the primary cause of acral mutilation syndrome?

Answer 23

pathologic lesions at the level of the primary sensory neuron, decrease in promeninence of the spinal ganglia and dorsal roots

Question 24

With epidermolysis bullosa simplex, where does clefting occur?

Answer 24

basal layer of epidermis (most superficial of epidermolysis bullosa types)

Question 25

Darier disease due to abnormal calcium homeostasis has been reported in what breed(s)?

Answer 25

English setters, Doberman pinscher

Question 26

Histopathologic changes with lethal acrodermatitis of Bull terriers?

Answer 26

diffuse parakeratotic hyperkeratosis with focal crusting and intraepidermal pustules; superficial epidermis may have laminar pallor

Question 27

Cutis laxa is due to abnormalities in what structure?

Answer 27

elastic fibers

Question 28

What is the defect in Ehlers Danlos?

Answer 28

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

Question 29

An ulcerative nasal dermatitis has been reported in what breed of cats?

Answer 29

Bengal cats

Question 30

What are the clinical features of canine cyclic hematopoiesis?

Answer 30

silver-gray hair coat, light-colored nose

Question 31

Canine cyclic hematopoiesis results from a mutation of the gene encoding what protein?

Answer 31

dog adaptor protein complex 3 (APB3)

Question 32

Canine darier disease has been repoted in English setters due to a depltion of what?

Answer 32

SERCA2-gated stores

Question 33

What are the histopathologic changes are present with pattern baldness?

Answer 33

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

Question 34

With junctional epidermolysis bullosa, where does clefting occur?

Answer 34

lamina lucida of the dermoepidermal basement membrane

Question 35

What is the defect in canine Darier disease and why does it result in clinical disease?

Answer 35

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

Question 36

What are the histopathologic features of Schnauzer comedo syndrome?

Answer 36

keratinous plug blocking the hair follicle and sebaceous gland --> cystic cavity is formed by stretched follicular epithelium and filled with keratin and sebum

Question 37

T/F: Mexiacn hairless dogs have a shorter lifespan than their haired relatives.

Answer 37

True - unclear if there is a familial immunoincompetence linked to hairlessness

Question 38

Which typically occurs first with dermatomyositis: skin or muscle lesions?

Answer 38

skin - myositis typically occurs months after the skin lesions

Question 39

Canine cyclic hematopoiesis has what mode of inheritance?

Answer 39

lethal autosomal recessive

Question 40

T/F: Biopsy is necessary to confirm a diagnosis of idiopathic facial dermatitis of Persian and Himalayan cats.

Answer 40

False - is often nondiagnostic

Question 41

Chediak-Higashi syndrome has what mode of inheritance?

Answer 41

autosomal recessive

Question 42

What are the histopathologic features of follicular lipidosis?

Answer 42

severe swelling of the matrix cells of anagen hair follicles due to accumulation of lipid within the cell's cytoplasm

Question 43

What are the histopathologic features of dermatomyositis?

Answer 43

hydropic degeneration of surface and follicular basal cells; apoptotic basal cells (Civatte bodies); perivascular to interstitial dermatitis; follicular atrophy and perifollicular fibrosis; vasculitis

Question 44

What is the presenting complaint with follicular lipidosis?

Answer 44

hair loss in the mahogany points of the face (in Rottweilers)

Question 45

What are the clinical features of psoriasiform-lichenoid dermatosis?

Answer 45

erythematous, lichenoid papules and plauqes on pinnae, external ear canal, inguinal region --> become hyperkeratotic

Question 46

Psoriasiform-lichenoid dermatosis is reported in what breed?

Answer 46

English Springer Spaniels

Question 47

Why are animals with ectodermal dysplasia more prone to respiratory infections?

Answer 47

decreased glandular secretions and impaired thermoregulation

Question 48

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?

Answer 48

electrolyte levels, esp. calcium, because calcitriol can decrease parathyroid hormone

Question 49

What stain is used to identify collagen disorders?

Answer 49

Masson trichrome stain

Question 50

What are the clinical lesions of junctional epidermolysis bullosa?

Answer 50

erosive to ulcerative lesions over bony prominences of the face, pinna, pressure points on the limbs or footpads, oral cavity

Question 51

What is the most common cutaneous manifestation of mastocytosis?

Answer 51

urticaria pigmentosa

Question 52

T/F: Steroids are beneficial in the treatment of canine darier disease.

Answer 52

Unclear -- in humans has clear benefit but not reported in dogs

Question 53

Histopathologic features of canine darier disease?

Answer 53

acanthosis w/ orthokeratotic and parakeratotic hyperkeratosis and marked, diffuse acantholysis of lower and middle portions of epidermis and follicular outer root sheath

Question 54

Histopathologic features of color dilution alopecia?

Answer 54

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

Question 55

Acral mutilation syndrome has been reported in what breeds?

Answer 55

German shorthaired pointers, English springer spaniel, English pointer dogs, French spaniels, miniature pinscher

Question 56

What histopathologic changes are present with black hair follicular dysplasia?

Answer 56

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

Question 57

What are the histopathologic features of psoriasiform-lichenoid dermatosis?

Answer 57

superficial perivascular to interstitial dermatitis with psoriasiform epidermal hyperplasia and areas of lichenoid interface dermatitis, intraepidermal microabscesses (containing eos and neuts), Munro microabscesses

Question 58

Follicular lipidosis has been reported in what breed?

Answer 58

Rottweiler

Question 59

What changes are present on skin biopsy with Ehlers Danlos?

Answer 59

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

Question 60

Darier disease has an autosomal (dominant/recessive) mode of inheritance?

Answer 60

dominant

Question 61

What changes are present on skin biopsy with ectodermal dysplasia?

Answer 61

hair follicles, arrector pili muscles, sebaceous glands, and epitrichial sweat glands are reduced in number, hypoplastic or absent

Question 62

_____ is an acquired defect in which external insults damage the cuticle and weaken the hair shaft.

Answer 62

trichorrhexis nodosa

Question 63

Where does the split occur with dystrophic epidermolysis bullosa?

Answer 63

sub-basilar dermoepidermal separation (beneath the lamina densa)

Question 64

Dermoid sinus has been reported in what breed of cats?

Answer 64

Burmese