Final - Dermatopathology Flashcards
(92 cards)
1
Q
Vesicle/Bulla
- Definition
- Causes
- Pathological Processes
- Changes that can lead to Vesicle/Bulla
- Typical Locations
A
- Palpable elevation filled with clear fluid
– Vesicle < 1cm
– Bulla > 1cm
- Causes
– Auto-immune dermatoses
– Viral infections
– Chemical irritants
– Burns
- Degeneration/Necrosis
Inflammation & Repair
4. Changes Intracellular Edema (spongiosis/Hydropic Degeneration) Disruption of intercellular Junctions (Acantholysis)
- All layers (Subcorneal, suprabasal, subepidermal)
2
Q
Pustule
- Definition
- Cause
- Pathological Processes
A
- Palpable elevation filled with pus
- Cause – leukocyte infiltrate
- Inflammation & Repair
3
Q
Crusts
- Definition
- Causes
- Pathological Process
A
- Dried exudate, serum, blood, and scale that is adhered to the skin surface
- Causes
– Severe disorders of keratinization
– Severe pustular dermatitis
– Secondary to ulcers - Degeneration/Necrosis
Inflammation/Repair
Disorders of Growth
4
Q
A
5
Q
A
6
Q
What is the MDx for Inflammation & Repair?
What are some ways to differentiate it?
A
______ dermatitis.
Tips for differentiating
- Look for ‘cardinal signs of inflammation’ – erythema, edema, exudate, heat, pain; + itching!
- If there are pustules/crust, there is an inflammatory component to the lesion
- Depigmentation – immune mediated inflammatory lesions
- If inflammatory infiltrate is severe enough, will see papules, plaques,nodules, but disorders of growth (neoplasia) can also result in these changes
7
Q
Describe the gross features of Dermatitis.
A
Early
– Edema
– Erythema
– +/- pustules, crust, vesicles
Later
– Scaling
– Change in oiliness
– Ulceration
– Alopecia
– Lichenification
– Pigmentary change
– Fibrosis/scarring
8
Q
What are the modifiers related to dermatitis and what do they indicate?
KNOW THIS
A
– Suppurative/Pustular/Exudative/Neutrophilic –bacterial, auto-immunity
– Proliferative – viral
– Vesicular – viral, auto-immunity
– Granulomatous – ‘higher’ bacteria, mycobacteria, fungal, foreign substance
– Eosinophilic – allergy, parasitic
– Interface – auto-immunity
9
Q
What kind of lesion is this?
What pathological process is it?
A
Dog with superficial spreading pyoderma, a superficial pyoderma with bacterial folliculitis
Inflammation and repair
10
Q
Pyoderma
What are the types of pyoderma?
A
Clinical term encompassing several diseases; “pus in the skin” – usually bacterial infection involved
Types:
-
Superficial – epidermis and hair follicles
– Disease examples
Canine superficial spreading pyoderma / Bacterial folliculitis
Impetigo (superficial pustular dermatitis)
Greasy pig disease
Dermatophilosis -
Deep – deep dermis
– Disease examples
• Bacterial furunculosis
• Abscesses
11
Q
How do bacterial infections of the skin occur?
A
Portals for:
Pores (follicular openings)
Hematogenous spread
Direct entry through damaged skin
Predisposing factors for:
Allergy
Disorders of keratinization (seborrhea)
Immunodeficiency
Anatomic predisposition
Common in dogs:
Thin stratum corneum, lack of lipid seal of hair follicles, high skin pH
12
Q
Bacterial infections often involve _____.
A
Staphylococcus spp.
13
Q
TRUE/FALSE.
One way that bacteria cause skin infections is through the production of exfoliative toxins that cause intraepidermal splitting.
A
TRUE
14
Q
This puppy is presented to you. Give:
- Disease Name
- MDx
- Cause
- Consequence/CS
A
- Impetigo
- Pustular Dermatitis, a type of superficial pyoderma.
- Bacterial infection secondary to immunosuppression/debilitation
- Nonfollicular pustules, which develop into crusts.
Prepuscent puppies are otherwise healthy
Adults - Look for underlying disease.
15
Q
What’s going on with this puppy? Give:
- Disease Name
- MDx
- Pathogenesis
- What types of cells will you find?
A
- Intertrigo/Skin Fold pyoderma
- Neutrophilic dermatitis
- Closely apposed skin surfaces –> frictional trauma –> moisture –> opportunistic bacterial infections
- Neutrophils
16
Q
What is going on with this dog? Give
- Disease Name
- MDx/Gross lesions
- Pathogenesis
A
- Pyotraumatic Dermatitis (“Hot Spots”) - Very common in dogs
- MDx: ulcerative/exudative dermatitis.
Gross: Moist, alopecic, slightly raised, red well-circumscribed lesions –> ulceration/crusting - Pathogenesis:
– Self trauma –> bacterial infection
– Underlying pruritis – especially flea allergy dermatitis!
17
Q
What can you tell me that’s going on in this disease? Give:
- Disease Name
- MDx/Gross lesions
- Cause
- Predisposing factors/Consequences
A
- Greasy Pig Disease (Exudative Epidermitis)
- MDx: pustular to exudative dermatitis.
Gross: erythema –> pustules –> crusts - Caused by Staphylococcus hyicus
- Predisposing factors – other skin lesions, poor nutrition/husbandry, lacerations
- Fatal in neonatal pigs
18
Q
Ew. Give:
- Disease Name
- MDx/Gross Lesions
- Cause
- Pathogenesis
- Predisposing factors
- How would you diagnose this?
A
- Dermatophilosis aka rain rot
- MDx: Exudative dermatitis
Lesions on back or distal extremities - Caused by Dermatophilus congolensis – gram positive filamentous bacteria which subdivide longitudinally and transversely
- Stimulate neutrophilic exocytosis: pustules–>exudate –> matting of hair/wool –> alopecia
- Predisposing factors
– Wet weather in humid climates (“rain rot”) – prolonged wetting of skin/hair/wool allows penetration of epidermis by “zoospores” - Diagnosis in the crust (characteristic appearance of bacteria - tram track)
19
Q
What is this?
What does it look like and how would you differentiate it?
A
This is dermatophilosis
It looks similar to squamous cell carcinoma due to repeated sun exposure. You know it’s not because of the distribution of the lesions.
20
Q
What is this? Give:
- Disease Name
- MDx/Gross lesions
- DDx
- Diganostics
A
- Canine superficial spreading pyoderma - Usually secondary condition; Bacterial infection of superficial follicles and adjacent skin
- MDx: neutrophilic/exudative dermatitis/folliculitis.
Gross: scaling, erythematous macules (often circular –> ring shaped), papules, pustules, crusts, epidermal collarettes, alopecia - DDx: (Grossly indistinguishable)
– Dermatophytosis (‘ring worm’)
– Demodicosis -
Diagnostics:
– Cytology of pustule/crust • neutrophils with cocci
– Woods lamp
– Fungal culture
– Skin scraping
21
Q
What is the difference between folliculitis and furunculosis?
A
Furunculosis is more severe.
22
Q
What two conditions resemble Canine Superficial Spreading pyoderma?
What lesions do they have in common?
A
Demodicosis & Dermatophytosis
Both have Folliculitis; erythematous macules –> Alopecia/Scaling
23
Q
This dog presents to your clnic. You perform a skin scraping, demonstrated in the histology. Give
- Disease Name
- Cause
- MDx
- How do the lesions vary?
- What are the two forms that can affect dogs?
A
- Demodicosis
- Cause: Demodex spp. mite
- Neutrophilic Dermatitis/folliculitis w/ intrafollicular mites and bacteria; Gross MDx of Dog: Multifocal exudative dermatitis
- Lesion vary by host/mite species
– Distribution on body
– Neutrophilic to granulomatous (exudative vs nodular grossly) - In dogs
–Localized form (face, forelegs) – young dogs, self-limiting
– Generalized form - Familial with young dogs
Adult-onset – often associated with systemic disease such as neoplasia, endocrinopathy, or immunosuppressive therapy
24
Q
This animal presents to your clinic. What can you tell me?
A
- Dermatophytosis
- Cause: Epidermophyton, Microsporum, and Trichophyton spp. (keratinophilic fungi)
- Contagious – acquired by contact with scales shed from infected animals
- Colonize keratin, do not need to invade tissue to cause disease
- Self-limiting in healthy animals, can become chronic/generalized in immunocompromised animals
- Predisposing factors:
– Young or immunosuppressed – Hot/humid environments - Use GMS or Groscott (silver stains)
25
5 yo FS dog has acutely developed some nasty skin lesions...
How do we describe these changes?
What can we do to determine the pathological process and cause?
Final Diagnosis?
1. MDx: Pustular/exudative dermatitis; Lesion = pustules, crusts
2. There is leukocyte infiltrate of the epidermis. Pathlogical process is likely inflammatory
3. Tests:
* Skin scraping: No mites or fungus seen
* Wood’s lamp: No fluorescence
* Fungal culture: No growth
* Cytology of a pustule: Eosinophils, Some bacteria, but not within cytoplasm of leukocytes, and not many neutrophils
4. Eosinophilic pustular dermatitis with tintralesional acantholytic keratinocytes. Consisten with Pemphigus foliaceous
26
Pemphigus foliaceous
* “Pemphigus” – group of auto-immune diseases involving type II hypersensitivity against cell adhesion proteins (desmosomes)
* PF is the most common and milder form of pemphigus (reported in horses, dogs, cats and goats) – others are rare but covered in text
* Often involves face, ears, footpads, clawbeds
* Vesicles, pustules, crusts, ulcers
* Can be spontaneous, drug-induced, or associated with allergic skin disease
27
What is this?
Mdx: Proliferative dermatitis with “ballooning degeneration” & intracytoplasmic inclusion bodies
Comment: Consistent with swine-pox infection
28
Describe the lesions that occur with Pox Viruses
* Sequence of lesions: macule → papule → vesicle → umbilicated pustule → crust → scar
* Poxviruses have a gene whose product is similar to epidermal growth factor → epidermal hyperplasia
* Many cutaneous lesions only, some systemic and fatal
* Some are foreign animal diseases
* **Umbilicated center is very characteristic of pox viruses**
29
What do you know?
Lamb with contagious ecthyma, early papular to vesicular phase
MDx: papular/vesicular dermatitis/cheilitis.
Note the epidermal hyperplasia (acanthosis), ballooning degeneration, vesicle (V), and neutrophils accumulating in the vesicle, which subsequently results in the formation of a pustule. Epidermal hyperplasia, upward movement of the pustule, and rupture of the vesicle or pustule contribute to crust formation as seen in A. H&E stain.
30
What's this?
Lambs with contagious ecthyma, late crusty phase
MDx: pustular/exudative dermatitis/cheilitis.
31
Seeing lameness, anorexia, ptyalism in some backyard livestock...
Lesions are seen in cattle, sheep and pigs.
* Something is injuring keratinocytes... The pathological process is likely degeneration&necrosis or inflammatory
* Differential Diagnoses?? Viruses!!
* **Early herpesvirus**
* **Early poxvirus**
**Vesicular diseases – FMD, VSV, SVD, VES**
* The only sure way to distinguish these diseases is by laboratory testing
* Producers and private practitioners, are the first line of defense against these economically devastating diseases.
* WHENEVER YOU SEE ULCERS – LOOK FOR VESICLES!
32
What is this?
Cat with ulcerative facial dermatitis due to FHV-1
MDx: pustular/vesicular dermatitis/cheilitis/rhinitis.
McGavins
33
What is this?
Cow with pseudo-lumpy skin disease, a vesiculo-ulcerative dermatitis due to BHV-2
34
What is this?
Cows with herpesviral mammilitis, vesiculo-ulcerative mammillitis also due to a strain of BHV-2
35
Multiple lesions in 4 y/o mixed breed. All tests that were done were inconclusive.
Granulomatous Dermatitis w/o Agents (“sterile”)
36
Idiopathic Sterile Granuloma and Pyogranuloma Syndrome
Give the Pathogenesis
* Rare
* Esp. dogs
* Pathogenesis – cause unknown
* – Caused by fastidious unrecognized organisms?
* – Abnormal immune response to unidentified microbial antigen?
* – Variant of histiocytic neoplasia?
* Diagnosis of exclusion
37
What is this?
Include MDx and stain
* Fungal dermatitis
* MDx: Granulomatous dermatitis
* • Uncommon
* Pythium, Lagenidium spp.
* “Swamp Cancer” - clinically resembles neoplasia...invasive lesions, involvement of regional lymph nodes
* Dx with Culture + PCR – why?
38
What is this?
* Actinomycete Mycetomas
* Bacteria introduced by traumatic injury
* Nocardia and Actinomyces sp.
* Can form large clumps (grossly evident as ‘sulfur granules’)
* Gross - Nodules, ulceration, draining sinuses, involvement of underlying bone
* MDx: pyogranulomatous dermatitis.
39
What is this?
* Mycobacterial Dermatitis Feline leprosy
* Cause - Mycobacterium lepraemurium, obligate intracellular organism (potentially other strains)
* Cats in cold, wet areas
* Transmission unknown – biting insects?
* FIV/debilitation may be predisposing factors
* Numbers of mycobacteria in lesions can be low – might not see on histo
* DOES NOT GROW IN CULTURE – Must use PCR – Can not get sensitivity resultsa
40
What is this?
* Mycobacterial Dermatitis Opportunistic mycobacteriosis
* Cause – “atypical mycobacteria”, facultative saprophytes (inhabitants of soil, water, and decomposing vegetation)
* – Rapid-growing (more common) – M. fortuitum, M. smegmatis, M. chelonae, M. abscessus, M. thermoresistible
* – Slow-growing – M. avium-intracellulare complex, M. kansasii, M. ulcerans
* Infection tends to occur via wound contamination or traumatic implantation
* Usually localized, but can disseminate
* Can do culture and sensitivity
41
Nodules involving dorsal pinna, less commonly other distal extremities were found on this dog. He is outside frequently. No other hx available. What could it be? Lesions are chornic/granulomatous.
* Mycobacterial Dermatitis Canine Leproid Granuloma
* Cause – saprophytic mycobacteria
* Transmission – fly bites?
* Nodules involving dorsal pinna, less commonly other distal extremities
* Short coated breeds, esp Boxer
* Self-limiting in immunocompetent dogs but may last months
* Difficult to culture, may need PCR; but usually can find organisms with histo
* MDx: granulomatous dermatitis.
* ZN stain showing acid fast bacilli within macrophages
42
What is this?
Multiple puppies in the litter were affected. No other evident etiologies.
* Puppy Strangles (Juvenile sterile granulomatous dermatitis)
* Pups \< 4 mos old
* One or more in litter
* Pathogenesis unknown
* Gross – pustules, nodules, swelling of face, ears, mucocutaneous junctions
* Histo – (pyo)granulomatous dermatitis and panniculitis +/- lymphadenitis
* Fever, joint pain
* MDx: pyogranulomatous dermatitis.
43
This dog comes into your clinic. The owner said he has not stopped licking this spot. What is going on?
* “Lick Granuloma” Acral lick dermatitis
* Common in dogs
* Cause – persistent licking/chewing
* Underlying factors – boredom? Sensory polyneuropathy?
* Gross – extremities; circumscribed, hairless, and ulcerated
* Histo
– Not really a granuloma!
– Epidermal hyperplasia, granulation tissue, fibrosis
* MDx: dermal fibrosis and epidermal McGavins hyperplasia.
44
This is the histopathology of a dog that has come in with erythema, alopecia, scaling. What is the most likely pathological process?
* Inflammatory
* MDx: Eosinophilic dermatitis with epidermal hyperplasia
* Comments: no cause evident. Consistent with ALLERGIC SKIN DISEASE. Must distinguish clinically.
45
What are the types of Allergic Skin disease?
* Atopy
* Food Allergy Contact Hypersensitivity Insect Bite Hypersensitivity
* Distribution of lesions vary
* Gross
– Lesions due to self-inflicted trauma: erythema, alopecia, excoriation
– Lesions due to secondary pyoderma: papules, pustules, crusts
– Lesions due to chronicity: lichenification, hyperpigmentation, scaling (‘secondary seborrhea’)
* Histo
– Lymphocytic and eosinophilic dermatitis
46
Atopy
* Pathogenesis: Type I hypersensitivity to environmental allergens (“inhalant allergy”)
* Diagnose with intradermal skin testing
* Distribution - ventrum, face, distal
* extremities
* Dermatology for Animals
47
Contact Dermatitis
* Pathogenesis: Type IV hypersensitivity reaction; exposure via direct contact
– Plastics in food bowls
– Dyes in carpets
– Plant residues in bedding
* Low molecular weight haptens present in chemicals require binding to cell-associated proteins prior to being recognized by CD8+ (cytotoxic) T lymphocytes
* Distribution - depends on site of contact, often in poorly haired areas
* MDx: dermatitis.
48
Insect Bite Hypersensitivity
* Pathogenesis: Type I and/or IV hypersensitivity reaction
* Examples
– Culicoides saliva - horses
– Flea saliva - dogs and cats
– Mosquito saliva - cats
* Distribution: depends on areas favored by insect, but can become generalized
– Culicoides – tail base, withers, head
– Fleas – tail base (dog), neck (cats)
– Mosquito – nose and face
* Gross: often includes papules
* Histo: may have eosinophilic pustules, folliculitis, or granulomas
* MDx: papular/pustular dermatitis.
49
What is this?
Dog with flea bite hypersensitivity;
Remember: pyotraumatic dermatitis (secondary self-trauma associated pyoderma) very common with this condition.
MDx: chronic and exudative dermatitis.
50
“Miliary dermatitis” in Cats
Not a disease, a pattern of lesions.
Small crusty erythematous papules.
Commonly seen in cats with allergic skin disease.
51
What is this?
* ALSO not a disease, a pattern of lesions.
* Indolent ulcer – ulcers on upper lips.
* Eosinophilic plaque – discrete red to ulcerated plaques on abdomen or medial thighs.
* Eosinophilic granuloma – nodules (may be ulcerated) on thighs, face or mouth.
* Commonly seen in cats with allergic skin disease.
MDx: Eosinophilic ulcerative dermatitis/cheilitis.
52
Describie Eosinophilic Granulomas
* Grossly similar to non-eosinophilic granulomas
* Often see collagenolysis – due to proteolytic enzymes of eosinophil granules?
* Causes
– Parasite reaction
– Insect bite hypersenstivity
– Foreign body reaction
53
What type of skin reaction is seen in summer sores?
Case of cutaneous habronemiasis (“Summer sores”):
Cutaneous eosinophilic granulomas caused by larval migration of Habronema or Draschia sp. deposited into a wound by house or stable flies
MDx: eosinophilic and granulomatous dermatitis.
54
Discoid Lupus Erythematosus
* 2nd most common autoimmune skin disease
* Induction/exacerbation by UV light
* Dorsal nose and nasal planum \>\>\> pinnae, lips, periocular region \>\>\> oral mucosa
* Gross: depigmentation, erythema, scaling, erosion, ulceration, and crusting
* Histo: interface dermatitis
* DDx:
– Uveodermatologic syndrome–auto- immune disease against dermal and uveal melanocytes; esp arctic breeds
– Dermatomyositis
* MDx: lymphoplasmacytic interface dermatitis.
* Mononuclear leukocytes infiltrate at the epidermal junction and obscure the basal lamina
* There are several other immune-mediated dermatoses with similar interface dermatitis.
* Pigmentary incontinence
55
How can you ID circulatory disorders?
Tips for differentiating
- Discrete reddened areas (hemorrhage)!
- Lesions follow a linear pattern
- Lesions are in geometrical shapes (indicating mapping to a vascularsupply)
- Vascular lesions which result in ischemia -\> see gross features of degeneration/necrosis
56
MDx?
Generalized subcutaneous edema
\*\*it will look gelatinous when cutting and a clear fluid may exude
57
MDx?
Cause?
MDx: Multifocal cutaneous ecchymotic hemorrhages
Cause: Primary hemostasis defect (Vasculitis vs. thrombocytopenia)
58
Infarcts
- Gross Appearance
- Causes
**_Gross_**
* Sharply demarcated geometrical shaped dark red to blue area
* As time goes by becomes firm, dry, sunken, darkened (features of necrosis begin to predominate over hemorrhage)
**_Causes_**
Frost bite
Toxins causing extreme vasoconstriction (ergot)
Vasculitis
* Erysipelothrix rhusiopathiae
* Gram negative septicemias -
* Salmonella, Pasteurella, E. coli
* E. coli shiga toxin 2e (damages
* endothelium) “Edema Disease”
* Spider/snake bite
* Drug reaction
* Secondary to ulceration
59
You are called to see this pig on a farm. Give:
1. MDx
2. Disease Name
3. Cause
4. DDx
* MDx: Multifocal cutaneous infarcts.
Histo MDx --\> Vasculitis and thrombosis (with cutaneous hemorrhage and necrosis)
* Disease: Diamond skin disease
* Cause: Erysipelothrix rhusiopathiae
* DDx: Salmonellosis (+ African swine fever, hog cholera viruses)
60
This lesion was found on a pig. Give:
- MDx
- Disease Name
- Cause
Another pig with "diamond skin disease"
MDx: Cutaneous ecchymotic hemorrhage
Cause: E. rhusiopathiae bacteremia and associated vasculitis
61
This horse has..
**Purpura hemorrhagica**
Pathogenesis: Type III hypersensitivity immune-mediated vasculitis
Cause: Streptococcus equi infection (rarely with other infections or vaccinations)
Gross: Red or purple macules or patches (hemorrhage or infarct) in the skin or mucous membranes
Subcutaneous edema
62
What happened to this goat?
**Frost bite aka Dry Gangrene**
• Cause: exposure to cold temperature
• Pathogenesis:
– Formation of ice crystals which physically disrupt cells
– Vasoconstriction and endothelial damage--\> reduced blood flow --\> thrombosis --\> infarction
* Lesions in cold exposed extremities
63
12yo TB gelding with acute onset of ‘welts’...
* Pathological process: Vascular disease, superficially reflecting focal mast cell degeneration.
* Known as a wheal
64
Urticaria ("Hives")
Urticaria vs. Angiodema
* Dogs, horses
* Localized areas of edema
* – **Urticaria** – superficial dermis
* – **Angioedema** – dermis + subcutis
* Pathogenesis: Type I and III hypersensitivity; mast cell degranulation focal edema, congestion, pruritis
* Triggers – foods, drugs, antisera, insect stings
* Histo – subtle (don’t waste your time!)
* MDx: Multifocal cutaneous Edema and congestion
65
Causes of Developmental Anomalies
Things that injure cells at a critical stage of development. The defect depends on tissue tropism and timing.
1. _Genetic defect_ – inherited mutation, spontaneous somatic mutation
2. _In utero infection_ – BVD, bluetongue, border disease, akabane, panleukopenia, classical swine fever
3. _In utero exposure to teratogens_ – toxic plants, griseofulvin in cats
66
Hypotrichosis
* Less than the normal amount of hair
* Hereditary most common
* More susceptible to environmental extremes and infections
67
What's wrong with this stretchy pup?
Collagen Dysplasia (Cutaneous Asthenia, Dermatosparaxis, Ehlers-Danlos)
A, The skin is hyperextensible. In this dog, the skin can be stretched more than the skin of a normal dog.
B, The collagen bundles are irregular in size and shape and are arranged haphazardly. The abnormally formed collagen is responsible for the hyperextensibility of the skin, which predisposes to tearing with normal handling and activity. H&E stain.
C, Deeper level of the sample shown in B. Collagen bundles are stained blue. The variation in diameter and shape of the collagen bundles and their haphazard arrangement is accentuated with this stain. Masson's trichrome stain.
68
This calf was born like this.. QUE PASA?
Epitheliogenesis Imperfecta
Born without epithelium. Usually won't live long because there is more susceptibility to bacterial infections.
69
What is this? Half alligator right?
Ichthyosis - Developmental anomaly
* Really thickened stratum corneum
* Pathogenesis is not well understood
* Thought to involve a defect in cell adhesion proteins
* Animal will die because of fissures and cracks leaving ulcers susceptible to 2\* infections
70
What are endocrine disorders that can result in alopecia?
– Hypothyroidism
– Hyperadrenocorticism
– Hyperestrogenism (sertoli cell tumor)
– Alopecia X
71
What are some hair cycle abnormalities?
– Postclipping alopecia
– Telogen effluvium
– Antimitotic drugs - chemotherapeutics, immunosuppressants
72
What are some random things that may lead to alopecia? (Not endocrine or hair cycle abnormalities)
* Excessive grooming – feline psychogenic alopecia
* Self-trauma (pruritis) – ectoparasites, dermatitis of any cause, but particularly allergic skin disease
* Autoimmune - alopecia areata (antibodies made against hair follicle)
* General poor nutrition - hairs are produced weak
* Hyperkeratosis - interferes with the hair follicle decreasing hair production
* Cicatricial alopecia (scar)
73
Describe what's going on here.
**Symmetric alopecia and hyperpigmentation, hyperestrogenism (iatrogenic from diethylstilbestrol therapy), skin, dog.**
A, Note the symmetric alopecia and hyperpigmentation over the caudal dorsal trunk and caudolateral hind legs. In male dogs, the symmetric alopecia in conjunction with enlargement of nipples, pendulous prepuce, and attraction of other male dogs suggest the possibility of hyperestrogenism.
## Footnote
B, Note epidermal orthokeratotic hyperkeratosis (arrowhead), follicles dilated with keratin (F), and small atrophic follicles (arrows) in the telogen (resting) stage of the hair cycle. H&E stain.
74
Epidermal hyperplasia
Acanthosis vs. Hyperkeratosis
Acanthosis: Increased thickenss of stratums basale and spinosum
Hyperkeratosis: increased thickness of stratum corneum
Perakeratotic - nuclei retained
Orthokeratotis - anuclear
75
Hyperkeratosis
Gross - Scaling "seborhea"
Dry - sicca - dry skin and white-to-gray scales that exfoliate
Greasy - oleasa - excessive brown to yellow lipids
Seen with:
* Primary idiopathic Seborrhea
* Secondary Seborrhea
* Zinc Responsive Dermatosis
76
Primary Idiopathic Seborrhea
* Primary (Idiopathic seborrhea) - especially Cockers, Springers, Westies
* Inherited disorder of keratinization or cornification
* Pathogenesis: thought to involve hyperproliferation of the epidermis, hair follicle infundibulum, and sebaceous glands
77
Zinc responsive dermatosis
• Types
– Arctic breeds – inherited defect in zincabsorption
– Pigs and rapidly growing large-breed dogs fed low zinc diet
• Gross: scaling around mouth, chin, eyes, pressure points, pawpads
78
This pig has...
parakeratosis (zinc responsive dermatosis). - lesions are typically confined to the lower and ventral abdomen, thorax, limbs and feet.
79
Which one is normal?
What does the other have?
Top.
**Sarcoptic Mange**
An example of ‘secondary seborrhea’ due to chronic dermatitis
* Caused by Sarcoptes scabiei
* Highly contagious and zoonotic
* Pathogenesis: burrow into stratum corneum--\>intense pruritis through hypersensitivity mechanism--\>self trauma, chronic irritation--\> hyperkeratosis, lichenification, alopecia
* MDx: Chronic dermatitis
80
What is going on with this fox?
Alopecia on the back and flank of a fox with a sarcoptic mange infection. In the lower image you can see the pronounced hyperkeratosis and where the skin has started to crack. The cracking of the skin, combined with scratching and grooming lead to lesions that are prone to bacterial infection.
MDx: Chronic dermatitis
81
What is this?
* Cutaneous Soft Tissue Sarcomas (spindle cell tumors)
* Very common in dogs
* Types
– Fibrosarcoma
– Nerve sheath tumor
– Malignant fibrous histiocytoma
– Liposarcoma
– Myxosarcoma
* Have overlapping histological features and similar prognosis--\>treat the same
* Prognosis predicted by grade and margins
* Locally invasive, slow to metastasize
82
What is this?
**Papillomas**
* Caused by papilloma virus
* Pathogenesis: viral genes inactivate host tumor-suppressor proteins
* Benign, spontaneously regress
* Gross: horny cauliflower-like masses
83
What is this?
Mdx: Cutaneous fibropapillomas
Cause: papilloma virus
84
You're called out to treat this horse. The owner tells you that this site has been injured multiple times and it keeps recurring after treatment. Show 'em what you got.
* Equine Sarcoid
* Very common in young adult horses
* Thought to be caused by bovine papilloma virus
* Frequently involve sites of previous wounds
* Invasive, high rate of recurrence, but do not metastasize
* Gross: variable range from nodular to plaque-like to wart-like
* Histo: composed of both epithelial and dermal components – need a biopsy that is not ulcerated to diagnose!
85
This dog is brought to your clinic. You notice these ulcerated lesions that are particular to the lightly pigmented areas. What do you think?
**Squamous cell carcinoma**
Pathogenesis: solar radiation, chronic injury commonly involved
**Gross:**
– Verrucousandulcerated
– Poorlypigmented,sparsely haired, sun-exposed areas
Histo: keratinizing squamous cells gone wild
86
What is this?
Sebaceous adenoma
• Benign growth of dogs • Gross:
– White-yellow, greasy, cauliflower- like
87
What is this?
Benign growth of dogs \>\>\> cats
• Gross:
– Looks and feels like fat, only forming a nodule
• Histo:
– Lookslikenormalfat
88
This dog comes into your clinic.
Pathological process: neoplasia
Mast Cell Tumor
Dog - behavior varies with grade but all considered potentially malignant
Cats, horses - benign • Gross:
– Can look like anything
– Oftenresemblesinflammation
\*\*Tolouidine blue stain shows intracytoplasmic granules
89
An owner is worried about this dome-shaped lesion that appeared on her dog. What is it? What do you do?
**Histiocytoma**
Dogs, mostly young, but any age
Head, ears, neck, distal forelegs
Gross: dome-shaped
Cyto: round cells
Langerhans’ cell origin (epidermal dendritic antigen-presenting cell)
Benign, often spontaneously regress (don't have to treat)
90
What is this?
Pathological process: Neoplasia
Melanoma
* Dog, horse, angora goat
* Gross: usually dark brown
* Histo: characteristic “junctional change” (in nonulcerated biopsies!)
* Location, size, mitotic index, and cell morphology may help predict behavior
* – Canine: oral, mucocutaneous, subungual, often malignant; haired skin often benign
* – Gray horses • usually progressive and multicentric
* Junctional change
91
What can you tell me about these two kinds of neoplasms?
Pathogenesis: solar radiation
Young adult dogs
• Hemangiosarcoma
– Not as malignant as visceral counterparts
– Primary to skin or metastatic from visceral tumor
– Metastatic potential may vary with depth of tissue invasion
92
What is this?
* Cutaneous Lymphoma
* Many species, esp. dogs
* Poor prognosis
* • Epitheliotropic – T-cells
* • Nonepitheliotropic
* – T or B cells
