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Systemic Pathology I > Pathology of the Integumentary System, Pt. 4 > Flashcards

Pathology of the Integumentary System, Pt. 4 Flashcards

1
Q

How do acantholytic cells compare to macrophages?

A

ACANTHOLYTIC: loss of coherence between epidermal cells due to the breakdown of intercellular bridges

MACROPHAGES: phagocytic vacuoles

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2
Q

What is the most common cause of intraepidermal vessicular/pustular dermatitis?

A

acantholysis - loss of cohesion between keratinocytes resulting in the breakdown of the intracellular bridges (desmosomes)

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3
Q

What are the 2 features of acantholysis?

A
  1. formation of clefts, vesicles, pustules
  2. acantholytic cells: keratinocytes that separate completely from their neighbors, become round, with a round nucleus and eosinophilic cytoplasm
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4
Q

How does intraepidermal vesicular/pustular dermatitis progress?

A

transient, vesicles/bullae and pustules —> erosions, crusts

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5
Q

What are 3 causes of acantholysis?

A
  1. Pemphigus foliaceous - antibodies against desmocolin-1 in the desmosomes
  2. bacteria - Staph. pseudintermedius releases exotoxins
  3. dermatophyte - fungi release proteolytic enzymes
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6
Q

How does pemphigus foliaceous, pemphigus vulgaris, and subepidermal blistering disease clefts compare?

A

PF: subcorneal
PV: suprabasal
SBD: subepidermal (subbasal)

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7
Q

What causes pemphigus foliaceus? What type of hypersensitivity is this?

A

production of autoantibodies against desmocolin-1

Type II —> Ab-mediated

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8
Q

How does pemphigus foliaceus present? In what dogs is it most common? What needs to be ruled out before diagnosis?

A

pustules, erosions, and crusting on the face (+nasal planum), ears, and paw pads

middle-ages dogs

infections by bacteria and dermatophytes (culture, treat, see if lesions disappear)

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9
Q

What is seen on cytology and histology in pemphigus foliaceous?

A

CYTO: numerous neutrophils with acantholytic cells

HISTO: superficial intraepidermal (subcorneal) pustular dermatitis with acantholytic cells

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10
Q

Feline pemphigus foliaceus:

A
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11
Q

How does pemphigus vulgaris present? What is its cause?

A

vesicles and bullae —-> erosions and ulcers in the oral cavity, mucocutaneous junctions, and skin
- most common in middle-aged dogs

production of an autoantibody against desmoglein-3

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12
Q

What is seen histologically in pemphigus vulgaris?

A

acantholysis with suprabasilar clefting that look like a row of tombstones

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13
Q

Why do the vesicles at different places in pemphigus foliaceus and vulgaris?

A

PF - DSC-1 is present in keratinocytes of canine footpad and interfollicular epidermis, but not detected in the buccal mucosa

PV - DSG-3 is restricted to the basal and lower stratum spinosum on the footpad, haired skin, and buccal mucosa

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14
Q

What allows for bacterial infections due to normal commensal organisms?

A

skin barrier damage or immune deficiency (usually Staphylococcus pseudintermedius in dogs - canine pyoderma)

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15
Q

What is impetigo? What is a major predisposing factor? What microorganism causes this?

A

puppy pyoderma with pustules not associated with hair follicles on the sparsely haired area like ventral abdomen, perineum

cutaneous abrasions, immunosuppression caused by a newly developing immune system

Staphylococcus pseudintermedius

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16
Q

What is seen histologically in impetigo?

A

subcorneal pustules with bacteria +/- acantholysis

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17
Q

Impetigo, cytology:

A
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18
Q

What is dermatophytosis? How is it visualized histologically?

A

infection due to fungi, characterized by neutrophil accumulation and pustule formation

GMS silver stain that makes fungi stain black

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19
Q

What causes porcine exudative epidermitis?

A

(greasy pig disease)
Staphylococcus hyicus infection that produces exotoxins that causes intraepidermal cleavage and pustule/crust formation

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20
Q

What causes dermatophilosis? Where/in what animals is it most common?

A

(rain rot)
Dermatophilus congolensis

cattle, goats, sheep, and horses in hot and humid areas with heavy rainfall

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21
Q

What are 2 critical factors that can lead dermatophilosis? How does it prevent?

A
  1. skin trauma
  2. prolonged moisture

thick, yellow-brown keratinized crust on any area of the body

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22
Q

What are the 2 causes of subepidermal vesicular dermatitis?

A

(subepidermal blistering disease)

  1. congenital defect in structural proteins of BM zone and cytoskeleton of basal keratinocytes (epidermolysis bullosa)
  2. autoantibody targeting antigens of the BM protein (epidermolysis bullosa aquisita, bullous pemphigoid, mucous membrane pemphigoid)
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23
Q

What is the general prognosis of diseases with subepidermal vesicular dermatitis?

A

poor prognosis —> difficult to treat

24
Q

What is a major histology characteristic of subepidermal vesicular dermatitis?

A
25
Q

What are the gross lesions associated with subepidermal vesicular dermatitis?

A

vesicles —> ulcers

26
Q

What causes congenital epidermolysis bullosa? How does it present?

A

(aplasia cutis congenita, epitheliogenesis imperfecta)
congenital defect in structural proteins of the BM zone and cytoskeleton of basal keratinocytes

vesicles/bullae, erosions, ulcers, and sloughing skin, nails, or hooves (skin, oral cavity, extremities, paw pads

27
Q

How does mucous membrane pemphigoid (MMP) present? What makes it unique compared to other subepidermal vesicular diseases? What dogs are predisposed?

A

ulcers in the oral cavity, nasal region, periocular region, and genital region (no paw pad!)

has a better prognosis

German shepherds (aquired)

28
Q

What is perifolliculitits? Luminal folliculitis? Mural folliculitis, furunculosis?

A

inflammation around the hair follicle

inflammation of the lumen of the hair follicle

inflammation of the wall of the outer sheath

follicle rupture with inflammation

29
Q

Furunculosis:

A
30
Q

How does folliculitis present?

A

papules, pustules, and alopecia that elevate hair follicles

31
Q

What are the 3 major causes of folliculitis?

A
  1. bacterial infection - Staph. pseudintermedius
  2. dermatophyte infection
  3. Demodex mites
32
Q

What is superficial pyoderma? What is it usually secondary to? What is the primary cause?

A

bacterial infection confined to the upper layers of the skin and hair follicle

allergies, anatomic predispositions (skin folds)

Staph. pseudintermedius - commensal bacteria on dog skin and mucosa

33
Q

How does superficial pyoderma present? What is seen histologically?

A

papules, pustules, epidermal collarettes

pustular dermatitis and folliculitis with bacteria

34
Q

What is intertrigo?

A

dermatitis occurring in areas of skin folding, such as face folds, lip folds, tail folds, and vulvar areas
- surface bacterial overgrowth (epidermal collarettes)

35
Q

What is deep pyoderma? What breed is predisposed? What is the most common cause?

A

infection of the deep dermis and subcutis and deep portions of the follicle

German shepherds

Staph. pseudintermedius

36
Q

How does deep pyoderma present? What is seen histologically?

A

erythema, ulcers, hemorrhagic crusts, bullae, draining tracts, and pain anywhere, but mostly on the truck and pressure points

folliculitis —> furunculosis and cellulitits

37
Q

What causes post-grooming furunculosis? How does it present?

A

water immersion or exposure to grooming products contaminated with Pseudomonas aeruginosa

  • acute deep pyoderma: hemorrhagic crusts, papules, pustules, draining tracts
  • lethargy, fever, pain
38
Q

What causes dermatophytosis in dogs, cats, horses, and ruminants? Is it zoonotic?

A

DOG: Microsporum canis
CAT: Microsporum gypseum
HORSE: Trichophyton equinum
RUMINANT: Trichophyton verrucosum

YES

39
Q

What animals are predisposed to dermatophytosis?

A
  • young animals
  • Persians
  • Himalayans
40
Q

How does dermatophytosis present grossly? Histologically?

A

circular patches of scaling, alopecia, and papules (folliculitis)

folliculitis/furunculosis, arthrospores and hyphae in hair shafts

41
Q

How is dermatophytosis diagnosed?

A
  • hair pluck
  • toothbrush technique and dermatophyte test medium
  • PCR
42
Q

Dermatophytosis, histology:

A
43
Q

What typically causes Demodectic mange? How is it typically transmitted? What allows for disease to develop?

A
  • Demodex canis
  • Demodex injai (live deep in hair follicles —> deep skin scrape)

direct contact from mother to offspring during nursing (not much horizontal transfer)

underlying disease causing immunosuppression and folliculitis/furunculosis

44
Q

How does Demodectic mange present?

A

alopecia, crusting, scaling, and variable pruritus on face, head, neck, truck, and limbs

45
Q

Demodectic mange, histology:

A

folliculitis —> inflammatory cell invasion

46
Q

Ulcerative/erosive dermatitis:

A
47
Q

What causes feline herpesvirus dermatitis? How does it present? What can be accompanied by this infection?

A

Felid herpesvirus-1

erosions, ulcers, and crusts on the face/nasal planum and occasional limbs

  • rhinitis
  • conjunctivitis
48
Q

What is seen histologically in feline herpesvirus dermatitis?

A

eosinophilic dermatitis with ulcers, necrosis, and intraepithelial intranuclear viral inclusion bodies

49
Q

What causes contagious ecthyma? In what animals is it most common? How does it develop?

A

(orf, contagious pustular dermatitis, infectious labial dermatitis, soremouth, scabby mouth)

Parapoxvirus
sheep and goats

regression is usually complete by 4 weeks (zoonotic!)

50
Q

How does contagious ecthyma (orf) present?

A

vesicles, pustules, ulcers, and crusts commonly on lips, muzzle, face, and oral cavity

51
Q

What is seen histologically in contagious ecthyma (orf)?

A

epidermal hyperplasia, ballooning degeneration, eosinophilic intracytoplasmic inclusion bodies

52
Q

What is irritant contact dermatitis? How is it different from allergic contact dermatitis?

A

nonspecific inflammatory cutaneous reaction caused by direct contact with an irritating agent, such as caustic chemicals, characterized by edema, erythema and papules developing into scales and lichenification

DOESN’T require prior sensitization

53
Q

What causes thermal burns?

A
  • strong chemicals
  • electric currents
  • solar/microwave radiation
  • heating pads
  • hair driers
  • hot liquid
  • lightning strike
54
Q

What are the 3 types of photosensitization dermatitis?

A

TYPE I: primary —> ingestion of exogenous agents (plants with phytoporphorins, drugs)

TYPE II: endogenous —> congenital erythropoietic porphyria causing disturbance in porphyrin pigment metabolism

TYPE III: hepatogenous photosensitization —> plant toxins from Lantana camara and Senecio spp. and mycotoxins

55
Q

What causes hepatogenous photosensitization? How does it present? In what areas of the body is it most common?

A

impaired capacity of the liver to excrete phytoporphyrins, which increases their levels in the blood, causing dermatitis

erythema progressing to crusting, erosion, and ulcers —> intensely pruritic

sun-exposed (face, ears) and lightly pigmented regions

Systemic Pathology I (25 decks)

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