Dermatopathology Flashcards
1
Q
What are the 5 main pathological processes in dermatopathology?
A
- Degeneration and Necrosis
- Inflammation and Repair
- Circulatory Disorder
- Disorders of Growth
- Deposits and Pigmentations
2
Q
What is the difference between a vesicle and a bulla?
A
A vesicle is less than 1 cm
A bull is greater than 1 cm
3
Q
Describe what a vesicle or bulla are?
A
They are a palpable elevation filled with clear fluid.
4
Q
What types of things can cause a vesicle or a bulla to form?
A
Auto-immune dermatoses
Viral infections
Chemical irritants
Burns
5
Q
What are the 2 major types of edema that cause the formation of a vesicle or bulla?
A
Intercellular edema: spongiosis
Fluid accumulating between the cells.
Intracellularedema: hydropic degeneration
Lost osmotic balance and the cells are taking on too much water. More common with viral infections b/c the cell is preoccupied with assisting in viral replication.
6
Q
What are the 3 areas that a vesicle can form in the skin?
A
- Subcorneal
- Suprabasal
- Subepidermal
7
Q
What is this?
A
Pustule
Palpable elevation filled with pus.
8
Q
A pustule is an infiltration of what?
A
Leukocytes
9
Q
What is this?
A
Crust
Could be: dried exudate, serum, blood, or scale that is adhered to the skin surface.
*Scale=excessive keratin
10
Q
What causes crust to form?
A
Severe disorders of keratinization.
Severe pustular dermatitis. Ruptured pustules.
Secondary to ulcers.
11
Q
What is a papule?
A
Palpable, solid elevated mass less than 1 cm in diameter.
12
Q
What are 2 subtypes of papules?
A
Nodules
Greater than 1 cm in diameter and deep.
Plaques
Coalesced papules.
13
Q
What is this?
A
Plaques
Remember these are coalesced papules.
14
Q
What are the causes of papules?
A
Infiltrate of inflammatory cells
Infiltrate of neoplastic cells
Epidermal hyperplasia
Deposit of mineral: especially Ca2+
15
Q
What is this?
A
Nodule
Remember this is a papule that is greater than 1 cm and deep.
16
Q
What is this?
A
Ulcer
Loss of epidermis with exposure of dermis.
17
Q
Ulcers often start out as an ______.
A
Erosion
18
Q
What can cause an ulcer?
A
Stress….j/k….but yeah probably….
Epidermal necrosis
Inflammation
Infarction
Neoplasia
19
Q
What is this?
A
Scale
aka Dandruff
Accumulation of loose keratinized cells.
20
Q
What causes scales to form?
A
Disorders of keratinization
Chronic dermatitis
21
Q
What are these?
A
Epidermal collarettes
A circular rim of scale that occurs secondary to the rupture of a vesicle, pustule or papule.
22
Q
What is this?
A
Lichenification
Thickening and hardening of the skin.
You will also get hyperpigmentation and erythema.
23
Q
What causes lichenification?
A
Chronic irritation/inflammation
24
Q
How would you describe this?
A
Tan-yellow firm plaque-like mass with an ulcerated surface.
Should point out that ulcers are typically depressed but this is elevated.
25
How would you describe this?
An area of crust on top of erythematous tissue.
26
What are 4 things you would **not want to do **when performing a biopsy?
Surgically prep the area
Grasp with forceps: *this would crush the cells and skew the morphology.*
Biopsy the center of a lesion
Hold out on telling the pathologist any important history or some potential differential diagnosis for fear it would influence pathologists opinion.
27
What are 4 things you **_would_** want to do when performing a biopsy?
Biopsy early prior to treating
Be gentle when grasping tissue
Collect multiple samples if possible
**Include the crusts:** *crusts are precious*
28
Degenerative and necrotic lesions tend to \_\_\_\_\_\_\_.
Ulcerate
## Footnote
*However, other pathological processes can do this too.*
29
Degenerative and necrotic lesions become ________ and ______ with time.
*Inflammation* and *repair*
***Normal response to injury and secondary infections are common.***
30
Primary _________ \_\_\_\_\_\_\_\_ often lead to degeneration and necrosis.
Circulatory disorders
31
How would you describe these lesions?
We have edema, erythema, alopecia, ulceration and crusting.
32
What are some differentials we should be thinking about when we look at these sheep?
*The history is that it's been sunny lately but they've been huddling in the shade.*
Photosensitization
Dermatophilus
Viral infections: Bluetongue, Pox virus (ORF/Scabby Mouth), Vesicular Disease (FMD/VS)
33
*You take a look at the pasture and see this plant growing; what is this?*
How can you r/o what is wrong with these sheep?
**St. John's Wort**
Can culture lesions, do a cytological prep, serology for viruses, PCR, or a biopsy.
34
* The blood work, serum ELISA for Bluetongue, and virus isolation from crust all come back as negative. _Histolopathology results show_ **epidermal necrosis and ulceration with etiology unknown and a 2ndary bacterial infection.***
* What is your diagnosis?*
**Photosensitization **from the St. John's Wort
## Footnote
*Knowing that St. John's Wort causes Primary: Type I Hypersensitization would explain why the sheep have photosensitization despite trying to huddle in the shade. Animals typically do not overexpose themselves. *
35
How many types of Primary Photosensitization are there?
2: Types I (Exogenous) and II (Intrinsic)
36
What is Primary: Type I Photosensitization caused from?
Plants containing photosensitive chemicals
ex: St. John's Wort, Lucerne, Perennial Ryegrass
37
What is Primary: Type II Photosensitization caused from?
Inherited deficiency of proporphyrinogen III\>\>
Cosynthetase\>\>
Defect in heme synthesis\>\>
Buildup of porphyrins\>\>
This causes **porphyria:** *which leads to pink teeth and pale oral mucous membranes.*
38
What is Secondary: Type III Photosensitization caused from?
Poor hepatic clearance of phylloerythrin (product of ruminal chlorphyll transformation.)
## Footnote
*Toxins cause biliary obstruction.*
***Most common in ruminants.***
39
What is the pathogenesis of photosensitization?
UV light absorbed by photodynamic chemicals in the skin\>\>
Leads to free radical damage\>\>
Epidermal necrosis of lightly pigmented or sparsely haired skin
40
How would you treat these sheep that are suffering from Primary: Type I (Exogenous) Photosensitization?
Move them to another paddock with shade and cover and no St. John's Wort.
Treat the animals with severe lesions which may have 2ndary bacterial infections.
41
What is this?
Solar injury
Acute UV light leads to a *sunburn.*
***Erythema\>blistering/vesicles\>sloughing of necrotic skin.***
42
What does chronic solar injury lead to?
Solar/actinic keratosis
## Footnote
*You get epidermal hyperplasia and dermal fibrosis and elastosis.*
43
With chronic solar injury animals have an increased risk of _________ due to direct DNA injury and subsequent mutations.
Neoplasia
44
What are thermal burns caused by?
Exposure to excessive heat.
## Footnote
*Hot liquids, flames, friction, electricity, heating pads, blow dryers, dry cages and lightening. *
45
How many **degrees** of thermal burns can you have?
3: 1st, 2nd and 3rd degree burns
46
Which type of burn do you have loss of the epidermis and dermis?
2nd degree burn
47
What type of burn do you have sloughing of necrotic tissue, followed by granulation tissue?
3rd degree burns
48
What type of burns do you have complete healing?
1st degree burn
49
What type of burn do you have loss of epidermis only?
1st degree burn
50
What type of type of burn do you have scar formation and that can be life-threatening from fluid, protein loss and is a portal for sepsis?
3rd degree burns
51
What degree of burn is this?
1st degree burn
52
What degree of burn do you have reddened/darkened necrotic epidermis?
1st degree burn
53
What type of burn do you have vesicle formation
2nd degree burn
54
What degree of burn do you have loss of the full thickness of the epidermis and dermis and potentially the subcutis as well?
3rd degree burns
55
What type of burn do you have some adnexa that are preserved allowing epidermal regeneration with *some scarring*.
2nd degree burns
56
What degree of burn is this and why?
3rd degree burn
## Footnote
*The full thickness of the skin is effected, no nuclei are present, and fluid has accumulated between the dermis and epidermis forming vesicles. Dry necrotic skin can be observed grossly.*
57
What caused this?
Chemical burn from bleach.
## Footnote
*Exposure is direct and must penetrate hair and protective epidermal layers.*
58
What is Erythema Multiforme and Toxic Epidermal Necrolysis?
Pathogenesis though to involve Type IV Hypersensitivity towards antigens or the surface of keratinocytes inducing apoptosis.
## Footnote
***Induced via antigenic mimcry from drug administration, underlying infection, neoplasia, and possibly dyes or preservatives in pet foods.***
* Causes widespread coalescing erythematous macules that lead to vesicles and ulcers.*
* \*Macules in picture.*
59
What is the difference between *Erythema Multiforme *and *Toxic Epidermal Necrolysis*?
**Erythema Multiforme**
*Milder and causes single celled apoptosis +/- lymphocyte satellitosis.*
**Toxic Epidermal Necrolysis**
*More severe, sheets of apoptotic/necrotic cells resembling a burn. *
60
What are the cardinal signs of inflammation?
Erythema
Edema
Exudate
Heat
Pain
+/- Pruritis
61
If there are ________ or ________ there is an inflammatory component to the lesion.
*Pustules *or *Crust*
62
\_\_\_\_\_\_\_\_\_\_\_\_\_ is immune mediated inflammatory lesions.
Depigmentation
63
If inflammatory infiltrate is severe enough we will see \_\_\_\_\_\_\_, ________ and _________ but disorders of growth (neoplasia) can also result in these changes.
Papules, Plaques and Nodules
64
What are the ***early*** gross features of dermatitis?
Edema
Erythema
+/- pustules, crust, vesicles
65
What are the late gross features of dermatitis?
Scaling
Ulceration
Alopecia
Lichenification
Pigmentary change: *Hyper or Hypopigmentation*
Fibrosis/scarring
66
What are some causes of inflammation and repair?
* Suppurative/Pustular/Exudative/Neutrophilic*-bacterial, auto-immunity
* Proliferative*- viral
* Vesicular*- viral, auto-immunity
* Granulomatous*- "higher bacteria", mycobacteria, fungal, or a foreign substance
* Eosinophilic*- allergy, parasitic
* Interface*- auto-immunity
67
What is this?
Pyoderma
## Footnote
*"Pus in the skin"--typically bacterial infection is involved.*
***There are 2 types: Superficial and Deep***
***~the picture shows superficial spreading pyoderma***
68
What is superficial pyoderma?
It affects the epidermis and hair follicles.
## Footnote
* ex: Canine superficial spreading pyoderma/bacterial folliculitis*
* Impetigo (superficial pustular dermatitis)*
* Greasy pig disease: caused by S. hyicus *
* Dermatophilosis*
69
What is deep pyoderma?
It affects the deep dermis.
## Footnote
* ex: Bacterial furunculosis*
* Abscesses*
***Shown is a dog with deep chin acne (basically like small abscesses), a deep pyodema with bacterial furunculosis***
70
What is furunculosis?
Infected hair follicle that has ruptured. You have a strong neutrophilic and pyodermic response.
71
What are some portals for bacterial infection?
Pores: *follicular openings*
Hematogenous spread: *usually associated with thrombis or infarction if spread through the blood.*
Direct entry through damaged skin
72
What are some predisposing factors for bacterial infection?
Allergies
Disorders of keratinization: *seborrhea*
Immunodeficiency
Anatomic predisposition
Ectoparasites: *such as mites*
73
Bacterial infections of the skin often involve what genus of bacteria?
***Staphylococcus spp.***
*The exception is opportunistic Gram (-) and cases of dermatophilosis.*
74
What is this?
Impetigo
## Footnote
*Superficial pustular dermatitis*
**Non follicular pustules will develop into crusts.**
**Typically develop in prepubsescent puppies that are otherwise healthy.**
**If this occurs in adults you should be looking for underlying disease.**
**Typically associated with Staph spp. infections**
75
What is this?
Intertrigo
## Footnote
*Skin fold pyoderma*
**You have 2 closely apposed skin surfaces, frictional trauma occurs, leads to moisture, and trapping of bacteria which in turn leads to infection.**
76
What is this?
Pyotraumatic dermatitis
## Footnote
*Hot spot or Acute moist dermatitis*
**This is very common in dogs.**
**Typically from self trauma which leads to secondary bacterial infection.**
**Grossly: Alopecia, slight raised, red, well-circumscribed lesion that leads to ulceration and crusting.**
**Underlying pruritis: possibly flea allergy.**
77
What is this?
## Footnote
*Species is a pig.*
Greasy pig disease
## Footnote
*Exudative epidermitis*
**Fatal in neonatal pigs.**
**Causative agent: Staphylococcus hyicus**
**Grossly: erythema which leads to pustules and then crust.**
**Other predisposing factors: other skin lesions, poor husbandry, or nutrition, lacerations, etc.**
78
What is this?
## Footnote
*Species is a sheep.*
Hard to make a diagnosis based on this image alone.
79
From the previous picture of a sheep, you do a Gram stain which reveals these organisms....now what is your diagnosis?
*Dermatophilosis congolensis*
Gram positive filamentous bacteria: **characteristic train tracks apperance.**
Lesions are typically on the back as we saw, or in the distal extremities.
This bacteria stimulates neutrophilic exocytosis: pustules which leads to exudate, matting of the hair and wool, and subsequent alopecia.
***Predisposing factors: wet weather/humid climates: sometimes this is called rain rot or lumpy wool. Prolonged wetting of the skin hair and wool allows penetration of the epidermis by zoospores.***
80
What is this?
Canine superficial spreading pyoderma
## Footnote
**Usually this is a secondary condition.**
**Bacterial infection of the superficial follicles and adjacent skin.**
**Grossly: there is scaling, erythematous macules (often circular or ring shaped), papules, pustules, crusts, epidermal collarettes and alopecia.**
81
What is this?
Folliculitis (*follicular inflammation*) and furunculosis (*rupture of the follicle*)
82
What is this?
Demodicosis
*Although it should be pointed out that this is often indistinguishable from superficial spreading pyoderma.*
**Cause: Demodex, demodectic mange**
**Lesions will vary as well as their distribution on body. *May be localized in the face or forelegs or more generalized.***
**Adult onset usually indicates an underlying disease process.**
**Can be neutrophilic (exudative) to granulomatous (nodular) grossly.**
83
What are the causes of Dermatophytosis?
How do animals acquire Dermatophytosis?
What are some predisposing factors to Dermatophytosis?
*Epidermophyton, Microsporum and Trichophyton spp. --**keratinophilic fungi***
Contact with scales shed from infected animals.
Young or immunosuppressed or Hot/humid environments.
84
How would we grossly describe these changes?
What is the morphological diagnosis (MDx)?
What would be the etiological diagnosis (EDx)?
Crusting and ulceration periorbitally and around nares, depigmentation and erythema, and pustules present.
MDx: Exudative dermatitis or Pustular dermatitis
EDx: Bacterial dermatitis (*suspect*: would need to confirm with cytology or biopsy.)
85
So we get the cytology back on the previous dog and is noted that there is *some bacteria* but not within the cytoplasm of leukocytes and there isn't too many neutrophils. The biopsy however reveals this....
## Footnote
***What are these cells that the arrow is pointing too and what is this indicating the etiology is?***
*Acantholytic keratinocytes: **keratinocytes that have lost their cell to cell function.***
Consistent with _Pemphigus foliaceous_
86
What causes this?
We now know that....
**Pemphigus foliaceous**
is the cause.
*Pemphigus is a group of auto-immune diseases involving **Type II Hypersensitivity** against cell adhesion proteins (desmosomes).*
***Can be spotaneous, drug induced, or associated with allergic skin disease.***
87
Pigs at a zoo came down with these lesions...
How would we describe these changes?
What would our MDx be?
This pathological process is likely what?
Multiple \<1 cm, slight raised and crusted papules and slightly solid.
*Papular dermatitis*
**Disturbance of growth** or **Inflammatory**
88
Most tests for the pigs showed NSF (no significant findings) except with the biopsy, these were seen [where arrow is pointing].
*What is the arrow pointing to and what is this indicative of?*
What would our MDx be?
*Swollen vacuolated cytoplasm or hydropic change. The cytoplasm is completely clear but it also contains eosinophilic globules which are **viral inclusion bodies.***
Consistent with: **Swine Pox infection**
MDx: *Proliferative dermatitis with **ballooning degeneration** and intracytoplasmic inclusion bodies.*
89
What are the sequence of lesions with Pox viruses?
Papule\>\>Vesicle\>\>Umbilicated pustule\>\>Crust\>\>Scar
90
If you see this, what should you be thinking?
Pox virus until proven otherwise
## Footnote
*Raised papule with a necrotic center.*
91
What is this poor lamb suffering from?
*Parapox virus*
***ORF, Scabby Mouth, Contagious Exanthema***
***_Zoonotic_***
Early papular to vesicular phase
92
What is the sheep suffering from?
*Parapox virus*
***ORF, Scabby Mouth, Contagious Exanthema***
***_Zoonotic:_*** ***below is shown a human hand with ORF: painful papule with an umbilicated center.***
Late crusty phase of disease with most likely secondary bacterial infection.
93
What is this on the foot of a pig?
What is the MDx of what this pig is suffering from?
Vesicle
## Footnote
*Just starting to rupture, skin flap lifted up and clear fluid is leaking out.*
***MDx:** Vesicular ulcerative pododermatitis*
94
What is this in the mouth of a sheep?
What is the MDx of what this sheep is suffering from?
Ulcer
MDx: *Vesicular ulcerative stomatitis*
95
What is the morphological diagnosis (MDx) of what this cow is suffering from?
MDx: *Vesicular ulcerative dermatitis*
96
What is the MDx of what this horse is suffering from?
**Mdx:** *Vesciular ulcerative stomatitis*
97
In the previous 4 slides, the pig, sheep, cow and horse have all been suffering from lameness, anorexia, ptyalism (drooling) and these lesions.
What is the most likely causitive agent?
How would we confirm what the causitive agent is?
***Viruses***
*Early herpesvirus, early poxvirus, or vesicular diseases such as FMD, VSV, SVD, and VES.*
***Laboratory testing***
**It turns out that this was VSV~ Vesicular Stomatitis Virus,** this affects cattle, pigs, horses and wildlife.
98
What is this?
*Vesicular ulcerative dermatitis* in the face of a cat caused by: **Feline Herpes Virus- 1**
99
What is this?
A cow with *vesicular ulcerative dermatitis* caused by **Bovine Herpes Virus- 2.**
## Footnote
***Pseudo-Lumpy Skin Disease***
100
What is this?
A cow with *vesicular ulcerative mammillitis* caused by **Bovine Herpes Virus- 2.**
_Different strains have different predilection sites._
101
A 4 year old mixed breed dog has multiple lesions like this:
What is the most likely pathological process?
How would you describe these lesions?
Disturbance of growth (*neoplastic cells)* or inflammatory *(cells; granuloma). **We know it's not an abscess because there is no leukocytes.***
Plaques, papules and nodules in multiple foci.
102
A biopsy was done from the previous papule and here is what was found (**no infectious agents or foreign material were seen with special stains)**:
## Footnote
*How would we describe this?*
*Multifocal granulomatous dermatitis~ **sterile***
103
What is this?
Idiopathic Sterile Granuloma and Pyogranuloma Syndrome
* Rare*
* Found mostly in dogs*
* Pathogenesis is unknown*
104
What is this?
Fungal dermatitis
***Pythium,*** *Lagenidium spp.*
***Swamp Cancer, or Florida Horse Leeches***
Pythium insidiosum mainly seen in dogs and horses
**Clinically resembles neoplasia, they are very invasive and spread to regional lymph nodes.**
105
