Module 8: Scaling, Crusting Disorders, and Miscellaneous Skin Conditions of Small Animals (Weeks 10 & 11) Flashcards by Kianelys Heredia

Introduction to autoimmune Skin Diseases

How well did you know this?

Not at all

Perfectly

Definition:
Are characterized by tissue damage in anatomically diverse locations

Autoimmune disorders

How well did you know this?

Not at all

Perfectly

Autoimmune Skin Diseases:
Inflammation is mediated by …

Innate cells
Migrating autoreactive lymphocytes
Circulating pathogenic autoantibodies

How well did you know this?

Not at all

Perfectly

Self-reactive T cells are activated inappropriately by microbial peptides with homology to those from self
Example: “Fogo Salvagem” (wildfire)
- Endemic form of pemphigus foliaceus (PF) in Brazil, associated with sandfly bites
- Protein of the salivary glands of the sandfly crossreact with Desmoglein -1, the main autoantibody in human PF

Molecular Mimicry

How well did you know this?

Not at all

Perfectly

Is a diversification of the epitopes recognized by the immune system

Epitope Spreading
- an epitope is an antigenic determinant, or a site on the surface of an antigenic molecule, to which a single antibody binds

How well did you know this?

Not at all

Perfectly

Auto-reactive B & T cells are activated in an antigen-independent manner
E.g. There is a high incidence of allergies in Systemin Lupus Erythematosus (SLE) patients
- Inflammatory cytokines released in response to environmental antigens like house dust mites can activate autoantibody production by B cells

Bystander activation

How well did you know this?

Not at all

Perfectly

Autoimmune Skin Diseases:
In our patients, What are the most common autoimmune skin diseases of dogs and cats?

Pemphigus foliaceus (PF)
Facial Discoid Lupus erythematosus (DLE)

How well did you know this?

Not at all

Perfectly

What condition is characterized by a specific humoral or cell-mediated immune response against the body’s tissue?

Autoimmunity

How well did you know this?

Not at all

Perfectly

Pemphigus Complex

How well did you know this?

Not at all

Perfectly

Autoimmune Dermatoses and Life-Threatening Diseases

How well did you know this?

Not at all

Perfectly

List the most common autoimmune skin diseases of dogs and cats:

Pemphigus foliaceus (PF)
- superficial
Facial Discoid lupus eythematosus (DLE)

How well did you know this?

Not at all

Perfectly

Term:
is a condition characterized by a specific humoral or cell-mediated immune response against the body’s own tissue

Autoimmunity

How well did you know this?

Not at all

Perfectly

Term:
are a subfamily of desmosomal cadherins, the transmembrane constituents of desmosomes

Desmocollins

How well did you know this?

Not at all

Perfectly

Term:
- a structure by which two adjacent cells are attached, formed from protein plaques in the cell membranes linked by filaments.
- are intercellular structures that holds cells together

desmosome

How well did you know this?

Not at all

Perfectly

Autoantibodies are directed against desmocollins =(form part of the desmosomes)

Pemphigus
- Systemic signs are uncommon (WNL)
- Pruritus is variable
- we don’t see secondary infections very offen

How well did you know this?

Not at all

Perfectly

Term:
The binding of the antibodies to the desmocollins causes the release of enzymes that degrade the desmosomes

Acantholysis

How well did you know this?

Not at all

Perfectly

Pemphigus (Term):
are immature, detached keratinocytes that are the hallmark of pemphigus diseases

Acantholytic keratinocytes

How well did you know this?

Not at all

Perfectly

Trichophyton mentagrophytes can also cause …

Acanthosis

How well did you know this?

Not at all

Perfectly

What are the primary lesions for Pemphigus Foliaceus?

Pustules (rarely seen)

How well did you know this?

Not at all

Perfectly

What are the Secondary lesions for Pemphigus Foliaceus?

Crusts, scales, alopecia, erosions and erythema - Are seen more often

How well did you know this?

Not at all

Perfectly

What is the Distribution of the lesions for Pemphigus foliaceus?

Muzzle: dorsal aspect often affected
Pinnae- inner and outer aspect
Footpads: hyperkeratotic, crusty, maybe the only site affected
CATS (maybe the only place affected) Paronychia
General distribution
Oral mucosa rarely affected

How well did you know this?

Not at all

Perfectly

Term:
A skin infection that occurs around the nails

Paronychia

How well did you know this?

Not at all

Perfectly

Differential diagnosis:

Bacterial folliculitis
Dermatophytosis
Demodicosis
P. erythematosus
DLE
Superficial necrolytic dermatitis (footpads)
Zinc responsive dermatosis (footpads)
Cutaneous lymphoma

How well did you know this?

Not at all

Perfectly

What will you see in Skin cytology?

Multiple acantholytic keratinocytes
Nondegenerate neutrophils
+/- Eosinophils

How well did you know this?

Not at all

Perfectly

Localized Discoid Lupus Erythematosus

- Is the *second* most common autoimmune skin disease after PF - Only skin is affected, no systemic signs - Lesions are *exacerbated* by UV light

Discoid Lupus Erythematosus (DLE)

List the Clinical Signs for DLE:

- Initial Lesions: - Depigmentation and erythema of the planum nasale - Can progress to erosions, ulcers, scaling and crusts - Lesions usually heal with a scar -- loss of *cobblestone* architecture of the nose

Describe the distribution of the lesions for DLE:

- Often limited to the planum nasale and dorsal aspect of the muzzle - Other areas can be affected - Mucocutaneous junctions, scrotum, pinnae

Differential diagnosis:

- PF - P. erythematosus - Dermatomyositis (skin and muscle, scars) - Zinc responsive dermatosis

Pemphigus erythematosus

- Is *uncommon* - It is a benign form of Pemphigus - It does have some similarities to Discoid Lupus erythematous (DLE) - a crossover between PF and DLE?

Pemphigus erythematosus

List the clinical signs of Pemphigus erythematosus:

- Lesions are similar to PF, localized to the face and planum nasale - *Primary Lesions are rare* (Pustules) - *Secondary lesions are common* (Crusts, Erosion, Alopecia, erythema)

Describe the diagnosis of histopathology for Pemphigus erythematosus:

- Subcorneal or intraepidermal pustule - Basal keratinocyte vacuolization and presence of apoptotic cells in the basal layer

(T/F) Most cases of the autoimmune disease need lifelong treatment

True

(T/F) Approximately 50% of the cases respond to *oral glucocorticoids* as a sole therapy

True

(T/F) An early lesion of facial discoid lupus erythematosus is nasal depigmentation

True

Generalized DLE

- Is a newly recognized *canine variant* of *cutaneous lupus erythematosus* - Ten cases were recently described, criteria for diagnosis included: - > 3 months history of generalized skin lesions - Skin lesions resembling those of human - annular (discoid) to polycyclic plaques with depigmentation, adherent scaling, follicular plugging and central alopecia below the *neck* - Presence of *microscopic lesions* typical of DLE interface dermatitis with basal cell damage

Generalized discoid lupus erythematosus (GDLE)

Clinical Signs:

- 40% had mucocutaneous lesions most commonly around the genitalia - Pruritus in 40% of cases - Pain in 30% of cases (NO systemic clinical signs)

Histopathology:

- interface dermatitis with *basal cell vacuolization and apoptosis*

Vesicular cutaneous lupus erythematosus

- Ulceration dermatitis affecting predominantly the *ventrum* of *shelties and collies* also reported in border colli - *Mucocutaneous* junctions and the *concave* aspect of the *pinnae* can also be affected - Age of onset: 3-8 years old - Onset usually during *summer* - Females may be over-represented

Vesicular cutaneous lupus erythematosus - no systemic signs - may be painful - it affects the quality of life

Lupus disease responds very nicely to ...

Cyclosporine

Mucocutaneous lupus erythematosus

- Age 3-13 - Presence of mucocutaneous erosive lesions and lupus-specific histopathology - Most dogs start showing between 4-8 years of age - German Shepard Dogs - Dyschezia/dysuria

Mucocutaneous lupus erythematosus

What are the main differential diagnoses?

- Mucocutaneous pyoderma - Mucous membrane pemphigoid (autoimmune)

Exfoliative Cutaneous Lupus erythematous

- German Short-haired Pointers - Lesions: - *Scaling* - most common - Alopecia - Erythema - Erosions - Ulcers

Exfoliative Cutaneous Lupus erythematous - Distribution: Muzzle, pinna, Dorsum - Progressive, poorly responsive to treatment!

Life-threatening Skin Diseases

- Atopic dermatitis - Canine generalized demodicosis - Otitis externa/media - Deep pyoderma

common diseases Difficult to control

- Thymoma-associated exfoliative dermatosis - Severe *scaling* and *erythema* - Alopecia - Start on the head, neck and pinae - *Pruritus absent* or minimal; may be intense with secondary bacterial or Malassezia infections - Systemic signs - Respiratory signs - Cats - Paraneoplastic alopecia - pancreatic adenocarcinoma - Rare - cats (> 10 years) - Associated with *Pancreatic adenocarcinoma* - Glistering skin

Paraneoplastic syndromes

Cutaneous Adverse Drug Reactions

Most common: - Sulfonamides - Penicillins - Cephalosporins - Carprofen

Cutaneous Adverse Drug Reactions - Can be any drug though

(T/F) Clinical signs for Cutaneous Adverse Drug Reactions are extremely variable

True

Erythema Multiforme (EM)

- Exact pathogenesis is *unknown* - Could also be drug reactions - *Target lesions*

Erythema Multiforme (EM)

Toxic epidermal Necrolysis

- Rare - Vesiculobullous and ulcerative - Most cases are drug reactions - poor prognosis - skin biopsy immediately - drug withdrawal - nikolsky sign often present: gentle skin manipulation results in sloughing - wound management

Toxic epidermal Necrolysis

Cutaneous Vasculitis

Term: Cutaneous reaction pattern cause by diseases were blood vessel walls are target of an inflammatory response - Infection-bacterial, rickettsiala, viral, fungal - Malignancy - Food hypersensitivity - Drug reaction - Rabies vaccination - Metabolic diseases - SLE - Idiopathic

Cutaneous Vasculitis

Lesions for Cutaneous Vasculitis :

- Purpura - Hemorrhagic bullae - necrosis - ulcers - urticaria - atrophic skin - alopecia (non-inflammatory hair loss)

Locations for Cutaneous Vasculitis :

- Paws - Pinnae - Tail

(T/F) Not easy to document Cutaneous Vasculitis in histopathology

True

Management of Cutaneous Vasculitis:

- Pentoxifylline (anti-inflammatory effects)

Miscellaneous Skin Conditions of Small Animals

- Uncommon condition - 3 wks to 4 months of age - predisposed breeds (there are many - labradors ...

Juvenile cellulitis - A *sterile process*, no bacteria - probably vaccine or medication-induced

List clinical signs of Juvenile cellulitis:

- Pyrexia, lethargy, lameness, paresis - Facial swelling - Otitis externa common

Other Differentials you should have in mind:

- Deep pyoderma - Demodicosis - deep skin scrape - Angioedema

List the treatment for Juvenile cellulitis:

- Systemic glucocorticoids - Prednisone - then slowly taper prednisone once the lesion is in remission - Oral antibiotics if secondary infection present - Recurrence is rare

(T/F) You can vaccinate a puppy with Juvenile cellulitis

False

Diseases of the Claw

- Rare - Claws are composed of hard and soft keratin - Claws grow slowly

Diseases of the Claw

What is the most common claw disease that you would see?

Paronychia

Common Claw terminology: Malformed

Onychodystrophy

Common Claw terminology: - Abnormal hypertrophy & curving

Onychogryphosis

Common Claw terminology: Complete loss

Onychomadesis

Common Claw terminology: - Softening

Onychomalacia

Common Claw terminology: - Separation of claw from bed

Onycholysis

Common Claw terminology: - Brittle, splitting, breaking

Onychorrhexis

Common Claw terminology: Inflammation of tissue folds surrounding the claw

Paronychia

Dermatophytosis

Term: Fungal infection of the nail and the nail bed

Onychomycosis

Fungal Culture:

- Clean with 70% alcohocl - Scrape the nail bed

Neoplasia

Neoplasia - Squamous cell carcinoma - Melanoma - Mast cell tumor

Lung-digit syndrome in ...

cats

Sysmmetric Lupoid Onychodystrophy

- The most common inflammatory disease to cause abnormal claws - Cause - Unknown - Normally involves multiple claws on all four paws - Uncommon to rare in dogs - Most commonly seen in middle-aged dogs - Nails may be normal in appearance but come off

Sysmmetric Lupoid Onychodystrophy

Biopsy for Sysmmetric Lupoid Onychodystrophy requires:

Onychectomy

Treatment for Sysmmetric Lupoid Onychodystrophy:

- Empirical therapy - vitamin E - +/- food trial - Treat paronychia if present

Superficial Necrolytic Dermatitis (SND)

- Rare - *Affects humans*, dogs, cats, black rhinoceros

Superficial Necrolytic Dermatitis (SND)

Dogs - Hepathopathy (often unknown etiology) - Only 8% dogs have glucagonoma (glucagon-secreting pancreatic tumor) - elevated plasma glucagon levels

Superficial Necrolytic Dermatitis (SND) - skin lesions: degeneration of keratinocytes - Changes most likely caused by cellular starvation or other nutritional imbalance

- Most will present for skin lesions - hyperkeratotic paw pads - Crusting, erosions, ulcers, vesicles - +/- pruritus - can also present for *systemic illness* prior to skin lesions

Superficial Necrolytic Dermatitis (SND)

List the differential diagnosis of Superficial Necrolytic Dermatitis (SND) :

- PF - Systemic lupus erythematosus - Zinc responsive dermatosis - Generic dog food dermatosis

Superficial Necrolytic Dermatitis (SND) Diagnosis:

- *Abdominal Ultrasound* = Honeycomb pattern - *Histopathology* - RED: Parakeratosis , WHITE: Edema, BLUE: Hyperplastic stratum basale pattern - Skin Cytology - Bloodwork

Urticaria

- Superficial Dermal Edema and erythema - Localized or generalized - generally well demarcated - Variable pruritic - Can coalesce forming bizarre patterns

Urticaria - IN THE DERMAL LAYER - treat: Antihistamines

Causes of Urticaria:

- many things - Insect bite/sting - vaccinations, other injections - Drug reactions

Anal Sacs

Each anal sac is between the _______ and _______ anal sphincter and has one duct

internal, external

Describe what is *Normal in an anal sac*:

- *Bacteria, keratinocytes* - Seems to be relatively consistent within the same patient, but *highly variable between patients*

Term: Sac ruptures and material released into surrounding tissue -> cellulitis & fistula formation

Anal Sac abscess

What are the normal components of the anal sac?

- Desquamated keratinocytes - Normal bacterial flora - Glandular secretion

What treatment is not an appropriate treatment option for symmetric lupoid onychodystrophy?

Apoquel

List normal findings with superficial necrolytic dermatitis:

- Heterogenous echotexture ("honeycomb") of the hepatic parenchyma on abdominal ultrasound. - "Red, white, and blue" cutaneous changes on histopathology. - Crusting of the distal limbs and hyperkeratosis of the paw pads on dermatologic examination

What is the first line of therapy for the treatment of juvenile cellulitis?

Corticosteroids

Keratinization Disorders

Scaly skin is a very common clinical presentation in the dog

Seborrhea

List the Primary disorders of keratinization:

- Defect in the keratinizing epithelium or glandular function - Hereditary, breed predilections - Discourage breeding of affected dog

(T/F) Majority od cutaneous scaling dermatoses are secondary (80%)

True

- Mild to severely dry, waxy, or greasy - Comedones - Alopecia - Pruritus

Cutaneous scaling dermatoses

A scaling dermatosis should never be diagnosed as a primary cornification defect without ruling out ___________________

secondary causes of scaling

List some K-9 Primary keratinization disorders:

- ZInc-responsive dermatosis - Sebaceous adenitis/Granulomatous to pyogranulomatous peri adnexal dermatitis - Canine acne - Canine ichthyosis

List a feline primary Keratinization disorder:

Feline acne

- *Siberian Huskies*, Alaskan malamutes, bull terriers - Suggests genetic linkage: the *decreased capability to absorb zinc from the intestine* - Do not breed affected dogs - Age range: 6 months to 10.5 years - 41% before they were 2 years old

Zinc-Responsive Dermatosis - scaling, crusting, alopecia - head - mouth, chin, eyes, ears - pruritic

Biopsy for Zinc-Responsive Dermatosis:

Marked diffuse epidermal and follicular parakeratotic (nuclei are retained) hyperkeratosis

Treatment for Zinc-Responsive:

- Oral zinc supplementation -> vomiting side effect - low dose of glucocorticoids - Omega 3/6 - Keratolytic shampoos

Sebaceous Adenitis

Term: An *inflammatory disease* directed against the sebaceous glands

Sebaceous Adenitis - uncommon in dog, *rare in cats* - abnormal keratinization

Clinical Features: - No sex predilection - Young to middle-aged dogs - *Standard poodle*, Akita, Samoyed, Belgian Sheepdog, GSD, *Golden retrievers* - Bilaterally symmetrical - Dorsal surface - tight adherent to the fur

Long-coated Breeds

In the biopsy findings:

- Granulomatous inflammation at the level of the sebaceous glands - Advanced disease: absence of sebaceous glands

- "Short-coated" "sebaceous adenitis" - Vizsla, dachshund - an inflammatory disease directed against the *entire* periadnexal region with occasional destruction of the sebaceous glands - UNCOMMON in DOGS - Cause and pathogenesis: unknown

Granulomatous to Pyogranulomatous Periadnexal Dermatitis - Annular areas of scaling and alopecia that enlarge and coalesce - Intermittent edematous swelling of muzzle, lips, eyelids

- Hereditary and usually congenital - Defective certification, abnormal stratum corneum - scaling - Norfolk terror, jack russell terrier, golden retriever, American bulldog, great dane, ckcs - Definitive diagnosis; Biopsy/*Genetic testing*

Ichthyosis

- Norfolk terrier - autosomal recessive - Suprabasal keratinocyte vacuolation and lysis, hypergranulosis, marked hyperkeratosis - Mutation in K10 gene - Mild pigmented scale, alopecia, roughened skin

Epidermolytic Ichthyosis

Describe the histopathology for *Non-Epidermolytic Ichthyosis*:

Laminated (layer on the layer) Orthokeratotic hyperkeratosis - Breeds: *Jack Russell* (Severe), Golden Retriever (Common, late-onset), American Bulldog (in between severeness), Great Dane

Feline Acne

- Uncommon idiopathic disorder of follicular keratinization - Any breed, gender - *Not confined to adolescence*

Feline Acne

- Comedones - Chin, lower lip, upper lip - May progress to papules and pustules - folliculitis, furunculosis, Cellulitis (infection in subcutaneous tissues) - Alopecia - Edematous, thickened

Feline Acne