Diseases of the Epidermis Flashcards
1
Q
What are common pustular diseases of the epidermis?
A
- suppurative/pustular/ exudative/ neutrophilic - Bacterial or due to autoimmune
- pyoderma
- impetigo
- intertrigo
- hot spot
- exudative epidermitis
- dermatophilosis
- pemphigus foliaceous
2
Q
Define Pyoderma
A
- ‘Pus in the skin’, usually bacterial
3
Q
Superficial pyoderma
A
- affects epidermis & hair follicles
Examples:
* Canine superficial spreading pyoderma/Bacterial folliculitis
* Impetigo (superficial pustular dermatitis)
* Greasy Pig dz
* dermatophilosis
4
Q
Examples of Deep Dermis Pyoderma
A
- Bacterial furunculosis
- Abscesses
5
Q
Portals of entry for pyoderma
A
- follicular openings
- haematogenous spread
- direct entry thru damaged skin
6
Q
Predisposing factors to pyoderma?
A
- disorders of keratinisation (seborrhoea)
- endocrine dz
- chronic dermatitis - allergy, parasites, etc.
- immunodeficiency
- anatomic predisposition
7
Q
Why is pyoderma common in dogs?
A
- stratum corneum has a lack of lipid seal of hair follicles & an increase in skin pH
8
Q
What is impetigo?
A
- bacterial skin dz causing superficial non-follicular pustules
- Due to: Staphylococcus intermedius - exfoliative toxins that cause intraepidermal splitting
- Common in: prepubescent & pubescent dogs
- poor environmental hygiene or poor nutrition
- If present in adults: look for underlying suppression
9
Q
What pustular skin dz is present in this image?
A
pyoderma
10
Q
What is this skin condition?
A
Impetigo
11
Q
Intertrigo
A
- skin fold pyoderma
12
Q
What skin condition is present?
A
Intertrigo
13
Q
What is the pathogenesis of intertrigo?
A
- closely apposed skin surfaces –> frictional trauma –> moisture –> opportunistic bacterial infections +/- Malassezia
14
Q
Pyotraumatic dermatitis is also known as
A
- hot spots
15
Q
What is the pathogenesis of Pyotraumatic dermatitis?
A
- self trauma –> bacterial infection
- underlying pruritic skin, esp FAD
16
Q
What does pyotraumatic dermatitis look like grossly?
A
- moist, alopecic, slightly raised, red, well-circumscribed lesions leading to ulceration/crusting
17
Q
What is this?
A
Hot spot
Pyotraumatic dermatitis
18
Q
What is exudative epidermitis also known as?
A
- Greasy pig dz
19
Q
What characteristics are common to exudative epidermitis?
A
- small papules & pustules
- malodorous ‘greasy’ exudate
- starts on head, can be generalised w/i 24-48 hrs
- non-pruritic
20
Q
Describe the histopathology of exudative epidermitis
A
- subcorneal pustules
- neutrophilic exocytosis
- spongiosis
- intracellular oedema
21
Q
Greasy pig dz can be fatal to…
A
- neonatal pigs
22
Q
What does exudative epidermitis appear grossly?
A
- erythema –> pustules –> brownish ‘greasy’ exudates/crusts
23
Q
What are predisposing factors to exudative epidermitis?
A
- other skin lesions
- poor nutrition/husbandry
- lacerations
24
Q
What disease is present here?
A
Exudative epidermitis (Greasy pig dz)
25
What organism commonly leads to exudative epidermitis
* *Staphylococcus hyicus*
26
Dermatophilosis characteristics?
* lesions on back or distal extremities
* stimulates neutrophilic exocytosis: pustules --> exudate --> matting of hair/wool --> alopecia
* multiple layers of infected epidermis form a laminar structure
27
What are predisposing factors for dermatophilosis?
* wet weather in humid climates ("rain rot")
* prolonged wetting of skin/hair/wool allows penetration of epidermis by "zoospores"
28
What organism leads to dermatophilosis?
* *Dermatophilus congolensis* (Gram + filamentous bacteria)
29
Where would you find the organism that causes dermatophilosis?
* Dx in the crust
* Coccoid bodies germinate to form long filaments that undergo longitudinal & transverse septation 'Tram track' appearance
30
What condition is present?
Dermatophilosis
31
What condition is present?
Dermatophilosis
32
What is pemphigus?
* autoimmune dz's involving antibody-mediated rxn against cell adhesion proteins (desmosomes)
33
Pemphigus foliaceous is the most common and mildest form of pemphigus in what species?
horses, dogs, cats, goats
34
Pemphigus foliaceous can be due to:
* spontaneous
* drug-induced
* assoc'd w/ allergic skin dz
35
Where is pemphigus foliaceous most commonly found on the body?
* face
* ears
* footpads
* clawbeds
36
What dermatological signs are present in pemphigus foliaceous?
* vesicles
* pustules
* crusts
* ulcers
37
What condition is this?
Pemphigus foliaceous
38
What bullous diseases are common in the epidermis?
* pemphigus vulgaris
* bullous pemphigoid
* epidermolysis bullosa
39
What causes pemphigus vulgaris
* autoimune dz (dog/cat)
40
What dermatological features are present in pemphigus vulgaris?
* severe vesicobullous & ulcerative lesions due to demoglein 3 affecting desmosomes (suprabasilar keratinocytes)
41
What condition is present?
Pemphigus vulgaris
42
How common is pemphigus vulgaris?
Very rare
43
What is bullous pemphigoid?
* fluid-filled spaces within the epidermis or at the dermoepidermal junction
* Due to an antibody against a transmembrane glycoprotein of basal keratinocytes
44
What condition is present?
Bullous pemphigoid
45
Pemphigus foliaceous
| Parts of body affected, symptoms, commonality
Affects: top layer of skin, over whole body
Symptoms: shallow skin blisters; itchy skin, redness, crust
Type: most common
46
Pemphigus vulgaris
| Affects, symptoms, type
Affects: deep layers of skin whole body (incl mouth) & in particular trauma areas - claw folds, underarms, groins
Symptoms: deep ulcers; itchy skin & pain, fever, lethargy, depression, anorexia from mouth ulcers
Type: most serious - critical & life-threatening; devleops into bacterial infections which are common & fatal
47
What is epidermolysis bullosa?
* Mechanobullous dz
* common in dogs, cats, cattle, people
* can be hereditary or acquired
* leads to structural defects in basal cell layer (basement membrane)
* loss of epithelial integrity, blister formation
* acquired antibody to same structures
48
What disease is present?
Epidermolysis bullosa
49
whenever you see ulcers, you should look for...
vesicles
50
Vesicular diseases of **cattle** that have vesicles of out FMD, Vesicular stomatitis, swine vesicular dz, and vesicular exanthema
51
Vesicular diseases of **pigs** that have vesicles of out FMD, Vesicular stomatitis, swine vesicular dz, and vesicular exanthema
52
Vesicular diseases of **horses** that have vesicles of out FMD, Vesicular stomatitis, swine vesicular dz, and vesicular exanthema
53
Explain vesicle formation of Foot & Mouth Dz
* ingestion or aerosol exposure --> initial viral replication in pharynx & lungs --> targets lymphoid cells, macrophages, dendritic cells --> leukocyte trafficking to regional LNs --> replication phase in LNs --> systemic spread --> lysis of epithelial cells in the stratum spinosum of stratified squamous epithelium
54
What are necrotizing diseases of the epidermis?
* erythema multiforme
* toxic epidermal necrolysis
* superficial necrolytic dermatitis
* photosensitisation
* herpesvirus
* cowpox virus
* burns
55
Explain erythema multiforme & toxic epidermal necrolysis (TEN)
* Type IV hypersensitivity towards antigens on keratinocyte surface inducing apoptosis
* antigenic mimicry following drug admin, underlying infection, neoplasia, dyes/preservatives in pet food
56
Explain the gross appearance of erythema multiforme & Toxic epidermal necrolysis (TEN)
* widespread coalescing erythematous macules (target lesions) --> vesicles & ulcers (trunk, axilla, groin)
57
What condition is this? What is the characteristic sign?
* keratinocyte death (apoptosis) occurs w/ lymphocyte satellitosis
58
What condition is this? What are its characteristics?
* TEN (toxic epidermal necrolysis)
* very rare, severe, life-threatening syndrome
* Generalised dz (erythema multiforme) & >30% epithelial detachment
59
Superficial Necrolytic Dermatitis
* Hepatocutaneous syndrome
* Necrotising skin disorder (dogs > cats)
* Metabolic hepatic dz
* Cats = neoplasia
60
What condition is presented here?
Superficial necrolytic dermatitis
61
What is photosensistisation?
UV light absorbed by photodynamic chemicals in skin --> free radical damage --> epidermal necrosis of lightly pigmented or sparsely haired skin
62
Type 1 photosensitisation
| Due to, Examples of causes
* Due to ingestion of a photodynamic substances OR plants w/ photoreactive pigments OR mycotoxins, moulds, chemicals, drugs
* Ex: St. John's Wort, Lucerne, Perennial ryegrass, quinolones, griseofulvin
63
Type II photosensitisation (Intrinsic, tertiary)
* due to endogenous pigment accumulation OR defective porphyrin metabolism
* Ex: erythropoietic porphyria
64
Type III photosensitisation (secondary, hepatogenous)
* Due to abnormal build-up of phylloerythrin due to liver dz or biliary obstruction
* Ex: hepatogenous, secondary
65
Type IV photosensitisation
Idiopathic
66
Macroscopic changes of photosensitisation
* Present in unprotected, unpigmented skin
* erythema
* oedema
* pruritus
* extensive necrosis
* marked exudation
* *Mainly in herbivores (chlorophyll)*
67
Histopathology of photosensitisation
coagultive necrosis of epidermis, dermal oedema, fibrinoid degen of vessel walls & thrombosis
68
Bovine herpesvirus 2 causes what conditions in cattle? What parts of the body are affected?
* Bovine ulcerative mammilitis
* Pseudolumpy skin dz
* Affects: cutaneous
69
Bovine herpes virus 4 causes what conditions in cattle? What parts of the body are affected?
* Bovine herpes mammary pustular dermatitis
* Affects: cutaneous
70
Feline herpes virus 1 causes what condition in cats? What part of the body is affected?
* Feline facial dermatits & stomatitis
* Affects: cutaneous, oral, ocular, upper respiratory
71
Ovine herpes virus 2 causes what condition? In what species? What part of the body is affected? Where is this dz found?
Malignant Catarrhal fever
Cattle
cutaneous, oral, systemic
USA
72
What does the histology of herpesvirus look like?
* Severe necrosis & ulceration of the epidermis & dermis
* Massive exudation to form large superficial crusts
* Mixed dermal inflammation w/ numerous eosinophils
* Large amphophilic intranuclear inclusion bodies in the epithelium
73
What condition does this histology depict?
Herpesvirus
74
Pseudo-Lumpy Skin Dz (PLSD) causes...
* ulcerative mammilitis (self-limiting) on the udder & teats
* Generalised superficial cutaneous nodules w/ central depressions
75
What condition is modeled here?
Pseudo-lumpy skin dz (PLSD)
76
What condition is modeled here?
Pseudo-lumpy skin dz (PLSD)
77
Feline herpesvirus 1 is also known as
Feline herpesvirus ulcerative dermatitis
78
Feline herpesvirus 1 causes
* Upper resp tract dz: rhinotracheitis, conjunctivitis
* erosion & ulceration of the face (muzzle, periorbital regions, planum nasale)
79
What allows for resurgence of feline herpesvirus 1
stress & immunosuppression
80
Ovine herpesvirus 2 causes what condition?
Malignant Catarrhal Fever (MCF)
81
What are signs of ovine herpesvirus 2?
* Fever
* Depression
* Ocular & nasal d/c
* lesions of the buccal cavity & muzzle
* swelling of LN's
* Opacity of the corneas
* inappetance
* diarrhoea
* some have neurologic signs: ataxia, nystagmus, head pressing
## Footnote
Remember: this is in CATTLE
82
What condition is present here?
Malignant Catarrhal Fever
83
Feline Cowpox virus is caused by what virus?
* cowpoxvirus (orthopoxvirus)
84
Where is feline cowpox virus most common?
UK/IE
85
What does feline cowpox virus look like grossly?
* ulcerting, erythematous, crusted macule on head, neck, forelegs
86
What does feline cowpox virus look like on histology?
* severe ulceration
* serocellular crusting
* ballooning degeneration of keratinocytes (epidermis & hair follicles)
* Numrous, large intracytoplasmic, brightly eosinophilic inclusions
87
What condition is presented here?
Feline cowpox virus
88
Acute solar injury ('sunburn') is due to...
* acute severe UV light exposure --> sunburn
89
What does acute solar injury look like grossly?
erythema --> blistering/vesicles --> sloughing of necrotic skin
90
What is the pathogenesis of acute solar injury?
* direct cellular injury by ionizing radiation
* endothelial damage & cytokine production causes erythema
* years of UV exposure leads to solar/actinic keratosis
* Ventral abd/thx --> non-pigmented & sparsely haired skin is erythematous, has comedones, crusts, thickened
* Increases risk for neoplasia due to DNA injury/mutations
91
What condition is presented here?
Acute solar injury
92
What condition is presented here? What is the pathogenesis?
Solar keratosis --> neoplastic transformation --> squamous cell carcinoma (SCC)
Due to acute solar injury
93
What causes thermal burns?
* exposure to excessive heat (hot liquids, flames, friction, electricity, heating pads, blow dryers, drying cages, lightning
94
What signs are present in a 1st degree thermal burn?
* reddened/darkened necrotic epidermis
* complete healing
95
What signs are present in a second degree thermal burn?
* vesicle formation in the epidermis & dermis
* some adnexa preserved allowing epidermal regeneration & some scarring
96
What signs are present in third degree thermal burns?
* sloughing of necrotic tissue followed by granulation tissue
* scarring
* can be life-threatening (fluid/protein loss & protal for sepsis)
* Affects: full thickness epidermis & dermis +/- subcutis
97
What are some hyperplastic diseases of the epidermis?
* acral lick dermatitis
* malassezia dermatitis
* hyperplastic dermatosis of WHWT
* Actinic keratosis (solar)
* Pox virus/parapox virus
98
What causes acral lick dermatitis?
* self-trauma to a focal area, usually a dorsal distal extremity
* strong psychogenic component, but must also rule out allergy, bacterial, fungal dz, demodicosis, previous trauma, underlying joint dz
99
What does acral lick dermatitis look like grossly?
alopecic, firm, oval plaque
100
What does acral lick dermatitis look like histologically?
* compact hyperkeratosis
* severe irregular acanthosis +/- erosion or focal to extensive ulceration w/ exudation
* inflammatory cells perivascular, perifollicular, or diffuse
* perihidradenitis +/- deep folliculitis & furunculosis
101
What condition is present here?
acral lick dermatitis
(lick granuloma)
102
Malassezia dermatitis is very common in what species? Rare in what species?
Common in dogs
Rare in felines
103
Malassezia dermatitis is caused by what organism?
Yeast *(Malassezia pachydermatis)*
104
What signs are present with malassezia dermatitis?
* Excessive sebum production
* moisture accumulation
* disruption of normal barrier fxn
* hypersensitivity
* secondary to predisposing triggers
105
What does malassezia dermatitis look like grossly?
* focal/multifocal/generalised
* ventral neck, ventral abd, axilla, face, pinnae, feet, forelegs, skin folds
* Erythema
* greasy or waxy adherent scales & crusts
* hair loss
* hyperpigmentation
* lichenification
* 'musty' odour
106
What condition is presented here?
Malassezia dermatitis
107
Hyperplastic Dermatosis of WHWT (Westies) is also known as...
Armadillo Westie Syndrome
108
What are signs of Hyperplastic dermatosis of WHWT?
* severe, chronic hyperplastic skin dz
* hyperproliferative rxn pattern initiated by various inflammatory stimuli & infectious agents (usually Malassezia)
109
What does hyperplastic dermatosis of WHWT look like grossly?
* generalised erythema w/ lichenification
* hyperpigmentation
* alopecia
* malodorous brownish-grey, greasy exfoliative debris
* +/- pruritis Malassezia dermatitis & surface bacterial overgrowth or superficial pyoderma
110
What is the sequence of lesions in pox viruses?
macule --> papule --> vesicle --> umbilicated pustule --> crust --> scar
111
Parapox viruses cause what conditions?
Bovine papular stomatits, orf, parapox of red deer, pseudocowpox, sealpox
112
Orf affects what stages of life?
Lambs & weaners
Ewes at lambing
113
Where would lesions of Orf be found?
mouth, feet, teats
114
What does orf look like grossly?
* epidermal hyperplasia
* ballooning degeneration
* vessicles
* neutrophil accumulation in vesicle
* intracytoplasmic inclusions
115
What condition is present here?
Orf
116
What are diseases that produce abnormal cornification?
* seborrhea
* sebaceous adenitis
* nasodigital hyperkeratosis
* ichthyosis
* callus
* Zn-responsive dermatitis
117
What is seborrhea?
non-specific name for excessive scaling, crusing, & greasiness
118
What is primary idiopathic seborrhoea?
inherited faulty keratinisation present in animals <18-24 mos
Breeds: WHWT, Cocker spaniels, Labs
119
What causes secondary seborrhoea?
underlying endocrinopathies, allergies
120
Secondary seborrhea is often assoc'd w/
superficial pyoderma
Malassezia infection
Alopecia
121
What is the pathogenesis of primary idiopathic seborrhoea?
* invovles hyperproliferation of the epidermis, hair follicle infundibulum, and sebaceous glands
122
Describe the histopath of primary idiopathic seborrhoea
marked epidermal & follicular hyperkeratois + comedones
123
What condition is this?
primary idiopathic seborrhoea
124
What condition is this?
Canine ear margin seborrhoea
125
What are the features of canine ear margin seborrhoea?
* Seborrhoea on the margins of the pinnae - adherent keratinous deposits on the lateral & medial margins of the pinna
* Dachshunds predisposed
* Due to hypothyroidism
126
Sebaceous adenitis occurs in...
* dogs (rare in cats)
* Std poodle, Akita
127
What does sebaceous adenitis look like grossly?
* adherent scaling forming follicular casts or fronds
* coat qlty diminishes as dz progresses --> dull, dry, brittle, broken hairs
128
What does sebaceous adenitis look like histologically?
* **infalmmation of sebaceous glands** or absence of sebaceous glands w/ acanthosis
* **hyperkeratosis**
129
What is nasodigital hyperkeratosis?
* idiopathic disorder of cornification affecting the planum nasale & pawpads
* common to older dogs (rare in cats)
130
What does nasodigital hyperkeratosis look like grossly?
* Frondlike keratinous proliferations OR verrucous, ridged proliferations w/ feather-like splitting
* inflammation NOT present
* proliferative debris predominantly at pad margins
131
Nasodigital hyperkeratosis is similar to what other condition in what specific species/age of dog?
Nasal parakeratosis of labs <1 yr of age
132
What condition is this?
Nasodigital hyperkeratosis
133
What is ichthyosis?
* inherited skin disorder characterised by thickening & marked scaling of skin which can crack into plates & resemble fish scales
* Assoc'd w/ defects in epidermal barrier (intracellular lipid layers, cornified envelope, keratin proteins) resulting in increased production of stratum corneum (scaling)
134
What condition is this?
Ichthyosis
135
What is a callus?
* pressure point granuloma
* aka thickened plaque on bony prominences or pressure points due to repeated pressure or frictional trauma
* common in large/giant breeds
* Epidermal hyperplasia, hyperkeratosis, cystic hair follicles, furunculosis
136
What's this?
Callus/pressure point granuloma
137
What causes Zn responsive dermatosis?
Diet deficient in Zn, high in Ca/Fe/phytates or other Zn-chelating organisms
138
What are the signs of Zn responsive dermatosis in pigs?
* 2-4 mos old
* anorexia
* reduced growth rate
139
What are the two syndromes of Zn responsive dermatosis in dogs?
* Syndrome 1: Siberian huskies, Alaskan malamutes < 1 yr old
* Syndrome 2: Puppies of any breed
140
What does Zn responsive dermatosis look like in ruminants?
* Several in herd affected
* decreased appetite
* weight loss
* decreased milk production
* depression
* diarrhoea
141
What does Zn responsive dermatosis look like grossly?
scaling & crusting skin lesions mainly around the eyes, lips, nose, pressure points, foot pads
142
What does Zn responsiver dermatosis look like histologically?
* severe acanthosis, follicular parakeratosis
143
What breeds/species can get Zn responsive dermatosis as an autosomal recessive condition?
Cattle: Friesians, US Shorthorns
Dogs: Bull terriers
