Pathology of Integumentary System - Part 4 Flashcards
1
Q
What can be seen here?
A
Vesicles are filled with pus, that is why we call this Intraepidermal vesicular/pustular dermatitis.
Vesicle is formed because of a phenomeon called acantholysis.
2
Q
What is the most common cause of Intraepidermal vesicular/pustular dermatitis?
A
Most common cause: Acantholysis
3
Q
What is acantholysis?
A
Loss of cohesion between keratinocytes
resulting from a breakdown of the intercellular
bridges (desmosomes).
4
Q
What is the difference between acantholytic cells and acanthocytes?
A
Acantholytic cells: keratinocytes which separate
completely from their neighbors, become round, with
a round nucleus and eosinophilic cytoplasm
Acanthocytes are a type of RBC with irregularly shaped spikes. Formed due to a defect in the lipid content on the cell membrane.
5
Q
What are the major features of acantholysis?
A
Formation of clefts, vesicles, pustules
6
Q
A
Large vesicle is a pustule filled with lots of neutrohpils and the individual keratinocytes are acantholytic cells.
7
Q
What do you see clinically with intrapeidermal vesicular/pustular dermatitis?
A
- Transient: Vesicles (smaller)/bullae (larger) –> progresses to pustules
- Progress to erosions and crusts
8
Q
A
intrapeidermal vesicular/pustular dermatitis
Eventually forms crusties
9
Q
What are the causes of acantholysis?
A
- Pemphigus foliaceus
* Due to autoantibodies against desmocollin-1 - Bacteria (S. pseudintermedius)
* Due to the release of bacterial exotoxins. Toxins cleave desmosomal protein.
* This is the major cause of canine pyoderma - Dermatophyte
* Due to the release of proteolytic enzymes. Fungi will release proteolytic enzymes which also cleaves desmosomal proteins.
10
Q
What can be seen here?
A
Desmocolene 1 is located in the superifical layer of the epidermis so that is why you see a vesicle intraepidermally.
11
Q
What can be seen here?
A
Protein in lower layer of epidermis
12
Q
What can be seen here?
A
Basement membrane contains manny tine structures in this zone. Whenever one of the proteins is defected, you will see vesicles in the BM zone.
13
Q
Pemphigus foliaceus (PF) affects what age range of dogs?
A
Middle-aged dogs
14
Q
Pemphigus foliaceus (PF) is a condition in which autoantibodies are formed against _________-__ (_____;
in _____)
* Which type of hypersensitivity?
A
desmocollin-1, DSC1, dogs
Type II
15
Q
What do you see clinically with a case of Pemphigus foliaceus?
A
*Pustules, erosions, crusting
* Face (including nasal planum), ears, paw pads
16
Q
What do you see histologically with a case of Pemphigus foliaceus?
A
- Numerous neutrophils with acantholytic cells on
cytological examination. When you do cytology, and see acanthlytic cells in very large numbers, this is probably PF so biopsy and send to pathologist to confirm.
17
Q
In cases of Pemphigus foliaceus, you need to?
A
- Need to rule out infections by bacteria and dermatophyte.
- Biopsy is the only way you can confirm this diagnosis.
Rule out bacterial/other cause by culture the surface, submit crust for culture of aerobic bacteria dna submit for dermatophyte cultures, if you get positive results treat for those infections first. If still have lesions, want to investigate further to see if have PF.
18
Q
What can be seen here?
A
Pemphigus foliaceus
19
Q
What can be seen here?
A
Pemphigus foliaceus
20
Q
What can be seen here?
A
Same cell, different stain on the left.
Slide on left is stained with Giemmsa stain
21
Q
What can be seen here?
A
Crust on face, ears.
PF in cats
22
Q
Pemphigus vulgaris (PV)
1. This is a disease of what dog age range?
2. Clinically what do you see?
3. What is the pathogensis of this disease?
4. Histologically what do you see?
A
- Middle-aged dogs
- Vesicles and bullae → erosions and ulcers
* Check Oral cavity, mucocutaneous junctions, skin
- Vesicles and bullae → erosions and ulcers
- *Autoantibody against desmoglein-3 (DSG3) = expressed in buccal mucosa which is why you will see lesions in oral cavity.
- Acantholysis with suprabasilar clefting (row of
tombstones)
- Acantholysis with suprabasilar clefting (row of
23
Q
What can be seen here?
A
PV
24
Q
What can be seen here?
A
PV
25
What can be seen here?
Tombstoning is characteristic of PV
26
Desmocolene is only expressed in superficial layer.
In buccal mucosa, no positive stain (green).
IF result = stained in lower area.
27
Normal surface flora
Skin barrier damage or immune deficiency
↓
?
Invasion by “normal” or pathogenic bacteria
Usually Staphylococcus spp.
(Staphylococcus pseudintermedius in dogs)
28
Impetigo (Puppy Pyoderma)
1. Affects dogs of what age range?
2. What is the predisposing factor?
3. What is the most common cause?
4. What do you see clincially?
1. * Young puppies. Still developing their immune system so usually don't see in adults.
2. * Predisposing factor: Cutaneous
abrasions, immunosuppression
3. * Most commonly caused by
Staphylococcus pseudintermedius
4. * Sparsely haired area like ventral abdomen, perineum
* Pustules not associated with hair follicles
* Subcorneal pustules with bacteria +/- acantholysis
29
What can be seen here?
Impetigo (puppy pyoderma)
30
What can be seen here?
See subcorneal vesicles because the top layer is the straum corneum and you see a huge pustule.
31
What can be seen here?
Cocci engulfed by neutrophils.
32
Dogs on steroids for too long can develop pyoderma due to immunosuppression.
33
What can be seen in these images?
Left: Dermatophyte within hair follicle on left arrow, on right there is lots of inflammation with neutrophils and scattered keratinocytes.
Canine skin, case no. 12. (a) Intrafollicular pustule
containing many neutrophils and moderate numbers of acantholytic
keratinocytes (arrow head). Fungal hyphae (arrow) are present in the follicular
keratin (haematoxylin and eosin, ×20; bar = 50 μm). Culture if unsure about diagnosis. Meds?
Right: GMS stain used for fungi. Fungi stained black. Black arrows pointing to fungi.
34
Porcine exudative epidermitis (greasy pig
disease)
1. What is the cause?
2. Produces?
1. * Cause: Staphylococcus hyicus. This is the commensal of pigs.
2. * Produces exotoxins
→ intra-epidermal cleavage --> acantolytic cells, pustules, crusts eventually.
→ pustules and crust
35
What can be seen here?
Porcine exudative epidermitis (greasy pig
disease)
Grease due to very active inflammation of skin.
36
Dermatophilosis
1. What is the cause?
2. Mostly seen in which species?
3. Alternative name? Why?
4. What are the critical factors leading to this disease?
1. * Cause: Dermatophilus congolensis
2. * Cattle, goats, sheep, and horses
3. Rain rot. B/c Most common in hot humid areas with heavy rainfall
4. Two critical factors:
* Trauma to skin
* Prolonged moisture
* Thick, yellow-brown keratinized
crust on any area of the body
37
What can be seen here?
Yellow or brown crusts that is involving the neck area. Not only do dermatophylosis can be a primary pathogen, can also be a secondary invader. E.g. if animal has viral infection, they can have secondary dermatophylosis because this is a type of bacteria that causes infection when you have trauma to the skin and if weather is humid.
38
What can be seen here?
Dermatophilus filaments
39
Self-assessment –
Intraepidermal vesicular/pustular dermatitis
* What are the clinical and histologic
features of intraepidermal
vesicular/pustular dermatitis?
* What are the causes of acantholysis and
what is the underlying pathogenesis?
* Which type of hypersensitivity reaction
underlies the pathogenesis?
* What structure is the autoantibody
directed in?
40
Subepidermal vesicular dermatitis
1. Also called?
2. Major causes?
3. What is the prognosis like?
1. * Subepidermal blistering disease
2. * Causes:
* Congenital defect (mutation) in structural proteins of
basement membrane zone and cytoskeleton of basal
keratinocytes. Die within a few weeks.
* Examples: Epidermolysis bullosa
* Autoantibody targeting antigens of the basement
membrane protein. Can treat with immunomodulatory drugs.
* Examples: Epidermolysis bullosa aquisita, bullous
pemphigoid, mucous membrane pemphigoid
3. Majority of these diseases often have poor
prognoses and often difficult to treat (except
MMP)
41
Subepidermal vesicular dermatitis
42
What can be seen here?
Subepidermal vesicular dermatitis
43
Subepidermal vesicular dermatitis
Ulcers.
Oral involvement
44
Congenital epidermolysis bullosa
1. What is this disease caused by?
2. What breeds does this effect?
3. Clinically what is seen?
4. What part of the body does this bacteria attack?
1. * Congenital defect (mutation) in structural proteins
of basement membrane zone and cytoskeleton of
basal keratinocytes
2. * Dogs, cats, pigs, cattle, sheep, goats, horses
3. * Vesicles/bullae, erosions, ulcers sloughing of skin,
nails, or hooves
4. * Skin, oral cavity, extremities, paw pads
45
What can be seen here?
Congenital epidermolysis bullosa
46
What can be seen here?
Mucous membrane pemphigoid (MMP)
47
Mucous membrane pemphigoid (MMP)
1. What breed is this most commonly seen in?
2. Characterized by? Effects which parts of the body?
1. German Shepherd dogs
predisposed
2. * Ulcers
* Oral cavity, nasal, periocular,
genital regions; no pawpaw
involvement
Subepidermal or pustule dermatitis.
48
What happens in folliculitis?
Starts with perifollicultiis aka inflammation around vesicles or folllcies. Then enters wall of follicles, then inflammatory cells enter lumen. Rupture of hair follicle of furun. Sinuses that connects to overlying skin --> draining sinus. Process
49
Perifolliculitis: inflammation around hair follicle
50
* Luminal Folliculitis: inflammation of the lumen of the hair follicle
51
* Mural folliculitis: inflammation within the wall of the outer root sheath
52
* Furunculosis: follicle rupture with inflammation
53
Folliculitis/perifolliculitis/furunculosis
Usually nodular. Rupture of hair follicle seen here
54
Clinically what do you see in cases of Folliculitis/perifolliculitis/furunculosis?
Dogs have so much hair on skin,so see any small papules which represent inflammed hair follicles. Hair is slightly elevated.
55
Folliculitis/perifolliculitis/furunculosis
Papules, pustules, alopecia
56
Folliculitis/perifolliculitis/furunculosis
Papules, pustules, alopecia
57
What are the three major causes of folliculitis?
1. Bacterial infection (esp. Staphylococcus pseudintermedius)
2. Dermatophyte
3. Demodex mites
58
Superficial pyoderma
1. What does this typically cause?
2. Common in what species?
3. Usually secondary to?
4. What is the primary cause?
5. What can be seen clinically?
6. Characterized by?
1. * Bacterial infection confined to the upper
layers of the skin and hair follicle (folliculitis)
2. * Common in dogs
3. * Usually secondary to allergies, anatomic
predispositions (skin folds), etc
4. * The primary cause is Staphylococcus
pseudintermedius
- * Commensal bacteria on dog skin and mucosa
6. Pustular dermatitis and folliculitis with
bacteria
59
What can be seen here?
Canine pyoderma
- Epidermal collarettes
60
What can be seen here?
Cocci engulfed by ?
61
What can be seen here?
Intertrigo
62
Intertrigo
1. What parts of the body are affected?
2. Common seen in which dog breeds?
3. Caused by?
1. * Dermatitis occurs in areas of skin folding such as face folds,
lipfold, tail fold, and vulvar area.
2. Dogs with lots of folds
3. * Surface bacterial overgrowth
63
What can be seen here?
Deep pyoderma
See ulcers on clinical presentations rather than little pustules or papules seen in superficial pyoderma. See erythema, sometimes hemorrhagic crusts or bullae.
64
Deep pyoderma
1. Defined as?
2. Which breeds are predisposed?
3. What is the most common cause?
4. Effects which part(s) of the body?
5. What can be seen grossly?
6. What can be seen histologically?
1. * Infection of the deep dermis and subcutis
and deep portions of the follicle
2. * German shepherds are predisposed
3. Most common cause: S. pseudintermedius
4. * Anywhere. Trunk and pressure points.
5. * Erythema, ulcers, hemorrhagic crusts,
bullae, draining tracts, pain
6.
* Folliculitis → Furunculosis and cellulitis
65
What can be seen here?
Post-grooming furunculosis
66
Post-grooming furunculosis
1. What is this disease caused by?
2. Most common cause?
3. Affects what part of the body?
4. Acute or chronic?
5. Causes what side effects?
1. Water immersion or exposure to
grooming products (e.g., shampoo,
brushing)
2. Most common cause: Pseudomonas aeruginosa
3. Trunk, dorsum, neck
4. Acute
5. Hemorrhagic
crusts, papules, pustules, draining tracks; * Lethargy, fever, and pain
67
Dermatophytosis
1. What dermatophyte do you see in dogs and cats?
2. What dermatophyte do you see in horses?
3. What dermatophyte do you see in ruminants?
4. Is this a zoonotic disease?
5. What age range is most affected?
6. Clinically what do you see?
7. Histologically what do you see?
1. Dogs and cats: Microsporum canis and Microsporum gypseum
2. Horses: Trichophyton equinum
3. Ruminants: Trichophyton verrucosum
4. Zoonotic
5. Young animals are predisposed (Persian and Himalayan cats)
6. Circular patches of scaling, alopecia, papules (folliculitis)
7. Folliculitis/furunculosis, arthrospores and hyphae in shafts
68
What can be seen here?
Focal nodules usually on face. Very common in dogs that go outside a lot and dig their face in soil. Dermatophytosis
69
What can be seen here?
Dermatphysis
70
What can be seen here?
Hair shaft destroyed by hyphae on left. Pluck the hair!
71
Diagnostics – Dermatophyte culture
* Hair pluck, toothbrush technique
* Dermatophyte test medium (DTM)
* Dermatophyte PCR
72
Clinician uses brush and then rubs on to DTM agar.
73
What can be seen here?
1. Cross section of hyphase.
2. Arthrospores
3. GMS stain to look for fungi.
Dermatophytosis
* Arthrospores within the hair follicle/shaft/stratum corneum
* Folliculitis
74
Demodectic mange
1. Is demodex a common or uncommon parasite?
2. What type of demodex are you looking for?
3. How is this parasite transmitted?
4. Caused by?
1. Common skin parasites of
numerous mammalian species so considered a common commensal. Immunosuppression --> infestation of demodex.
2. Demodex canis, D. injai; lives in
the hair follicles --> do a deep skin scrape
3. Transmission: direct contact from mother to offspring during nursing. Unlikely to be transmitted to another dog.
4. Underlying disease
→ immunosuppression
→ folliculitis/furunculosis
75
76
Clinically what do you see in cases of demodex mange?
* Alopecia, crusting, scaling, variable pruritus
* Face, head, neck, trunk, and limbs
77
What can be seen here?
Demodex mange = localized
78
What can be seen here?
Demodex mange = generalized
79
Inflammatory cells infiltrating hair follicle = follicultiis.
80
81
Self-assessment –
Perifolliculitis/Folliculitis/Furunculosis
* What’s the difference between folliculitis and furunculosis?
* What are the causes of folliculitis?
* How do you differentiate the causes of folliculitis?
82
83
Feline herpesvirus dermatitis
1. Caused by? Felid herpesvirus-1
*2. Clinically what do you see? Erosions, ulcers, crusts
3. Effects what part of the body? Face, nasal planum, and occasional limbs.
* Can have rhinitis, conjunctivitis
4. Histologically? Eosinophilic dermatitis with ulcers,
necrosis, and intraepithelial intranuclear
viral inclusion bodies
5. Can also cause? Conjunctivitis and UR signs
1. . Caused by? Felid herpesvirus-1
*2. Clinically what do you see? Erosions, ulcers, crusts
3. Effects what part of the body? Face, nasal planum, and occasional limbs.
* Can have rhinitis, conjunctivitis
4. Histologically? Eosinophilic dermatitis with ulcers,
necrosis, and intraepithelial intranuclear
viral inclusion bodies
5. Can also cause? Conjunctivitis and UR signs
84
Feline herpesvirus dermatitis
85
Feline herpesvirus dermatitis
86
Contagious ecthyma
Vesicles, crusts, and ulcers around face.
87
Epidermal hyperplasia, Keratinocytes exhibiting ballooning
degeneration, eosinophilic
intracytoplasmic inclusion body
88
Contagious ecthyma
1. Common disease caused by?
2. What species are affected?
3. Regression by?
4. Clinically you see?
5. What parts of the body are affected?
6. Histologically what do you see?
7. Is this a zoonotic disease?
1. Parapoxvirus
2. Sheep and goats
3. Regression is usually complete by 4 weeks
4. Vesicles, pustules, ulcers, crusts
5. Lips, muzzle, face, oral cavity
6. Epidermal hyperplasia, ballooning degeneration, eosinophilic
intracytoplasmic inclusion body
7. Zoonotic
89
Irritant contact dermatitis
Edema, erythema, sometimes ulcers on skin.
90
Irritant contact dermatitis
1. Caused by?
2. Clinically what do you see?
1. A nonspecific inflammatory
cutaneous reaction caused by direct
contact with an irritating agent such
as caustic chemicals
* NOT allergic contact dermatitis
* Does not require prior sensitization
2. Edema, erythema and papules →
scales, lichenification
91
Thermal Burn
Either ulcerative or necrotizing.
Whenver you are suspecting a burn on the animal, it can be a burn or a variety of causes you never even thought about it.
92
Thermal Burn
1. Can be caused by ?
2. What are the clinical signs?
1. strong
chemicals, electric currents,
solar and microwave
radiation, heating pads, hair
drier, hot liquid (garden hoses
left out in sun), electrical
burn, lightening strike etc.
2. Clinical signs vary based on
depth of burn
93
Photosensitization dermatitis
* Type 1: ______
* Caused by?
Primary
Ingestion of exogenous agents (plants, drugs). When animal ingest plants with phytoporiphorins which is UV reactive or photosensitive. When you can't get rid of photophoriphins, leads to this.
94
Photosensitization dermatitis
Type 2: _______
* Caused by?
Endogenous
Congenital erythropoietic porphyria - disturbance in porphyrin pigment
metabolism
95
Photosensitization dermatitis
Type 3: ?
* Main causes?
Hepatogenous photosensitization
plant toxins (Lantana camara, Senecio spp.) and
mycotoxins
96
Hepatogenous photosensitization
* Sun-exposed (face, ears) and lightly pigmented regions
* Intensively pruritic
* Erythema progressing to crusting,
erosion, ulcers
* Impaired capacity of the liver to
excrete phytoporphyrins → increase
in blood levels → dermatitis especially in lightly pigmented skin. Black part is usually not affected.
97
What can be seen here?
Heptaogenous photosensitization
Dermatitis especially in lightly pigmented skin. Black part is usually not affected.
