Dermatopathology Flashcards
(143 cards)
1
Q
During embryology, what does the neural tube become?
A
CNS
2
Q
What does the notochord induce during embryology?
A
Formation of the neural tube
3
Q
The notochord forms from which kind of cells?
A
Mesoderm cells
4
Q
What are the 5 layers of the epidermis?
A
Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
5
Q
What are the 3 stages of the hair cycle?
A
Anagen: active stage of hair growth
Catagen: hair stops growing but is not shed
Telogen: follicle recedes and hair falls out
6
Q
What is acantholysis?
A
Loss of keratinocytes cohesion
7
Q
What is acanthosis?
A
Increased thickness of stratum spinosum (often used to indicate epidermal hyperplasia)
8
Q
What is alopecia?
A
Hair loss or failure to grow
9
Q
What is atopy?
A
Allergic skin disease
10
Q
What is meant by ballooning degeneration?
A
Intracellular oedema
11
Q
What is a bullae?
A
Collection of fluid >1cm in diameter
12
Q
What is folliculitis?
A
Luminal, mural or peri-follicular inflammation of the hair follicle
13
Q
What is furunculosis?
A
Perifollicular inflammation due to hair follicle wall rupture (dermal pyogranulomatous inflammation)
14
Q
What is hyperkeratosis?
A
Increased thickness of the keratin layer, with (parakeratotic) or without (orthokeratotic) nuclei
15
Q
What is a pustule?
A
Cavitation of the epidermis filled with inflammatory cells
16
Q
What is pigmentary incontinence?
A
Melanin granules and melanophages within the dermis
17
Q
What is seborrhea?
A
Increased scale formation, with (S. oleosa) or without (S. sicca) excessive greasiness
18
Q
What is spongiosis?
A
Epidermal intercellular oedema
19
Q
What is a vesicle?
A
Fluid-filled blister
20
Q
What is greasy pig disease caused by?
A
Staphylococcus hyicus
21
Q
Skin lesions can be classified based on which 4 things?
A
Lesion type (eg bulla, pustule)
Distribution
Aetiological agents
Underlying pathogenetic mechanism (eg inflammatory)
22
Q
What causes ‘diamond’ skin lesions in pigs?
A
Erysipelothrix infection (bacteria)
23
Q
A neutrophilic vasculitis is suggestive of what?
A
A type III hypersensitivity reaction or septicaemia
24
Q
A lymphoplasmacytic vasculitis is suggestive of what?
A
Cell-mediated immune-response
25
What is eosinophilic vasculitis suggestive of?
Type I hypersensitivity reaction, or other eosinophil-dominated dermatoses (eg eosinophilic granuloma)
26
Describe impetigo
Superficial pustular dermatitis with NO involvement of the hair follicle
Erythematous papule -> pustules (composed mainly of neutrophils)
27
Describe greasy pig disease
Acute superficial exudative pyoderma of young (5-35 days old) pigs
Caused by Staphylococcus hyicus
Exotoxin produces cleavage between stratum layers
Greasy dark brown exudate over eyes, snout, chin, ears
3 clinical forms: peracute (rapid spread to body -> death), acute, subacute (lesions confined to head, more surviving piglets)
Bacterial colonies
28
Describe dermatophilosis
Acute to chronic exudative superficial dermatitis caused by Dermatophilus congolensis (gram + coccoid bacteria -> branching filaments)
Wet skin and skin trauma are favourable
Thick parakeratotic crusts (continuous epidermal invasion)
29
Describe deep pyoderma
Staphylococcus spp=most commonly involved bacteria
Follicular papula -> pustule -> crusts, coalescing ulcers, alopecia -> epidermal acanthosis (increased thickness of S.spinosum)
Histology: neutrophilic folliculitis and furunculosis, bacterial colonies -> free keratin fragments -> foreign body reaction and haemorrhages
30
Herpes viruses have which kind of inclusion bodies?
Intranuclear
31
Pox viruses have which kind of inclusion bodies?
Intracytoplasmic
32
Define poxviruses
DNA viruses with high epitheliotropism
Some have zoonotic potential
Capable of causing vesicular and proliferative lesions
33
Describe cowpox
Affects cats
Single lesions on face or forepaws
Ulcers -> papules and pustules
Histology: focal, sharply demarcated ulcer, covered with fibrinonecrotic exudate
34
Describe orf
Affects kids and lambs
High morbidity but low mortality
Affects lip commissure -> lips and muzzle -> legs (rarely)
Multifocal to coalescing raised and flat grey crusts
Histology: ballooning degeneration and spongiosis (intra- and intercellular oedema) with epidermal hyperplasia and crust formation
Zoonotic
35
Describe sheep pox
>50% mortality
Africa, Asia, Middle East
Cutaneous lesions are the expression of systemic disease (resp and GI systems)
Distribution: disseminated, esp. in sparsely wooled areas
Vesicles -> crusty pustules, papules -> dermal oedema
Histology: vesicles, pustules and papules due to vacuolar degeneration of S. spinosum, eosinophilic intracytoplasmic inclusion bodies (also within macrophages)
36
Describe swinepox
Negligible mortality
Distribution: ventrolateral abdomen, medial legs and lateral thorax
Erythematous papules -> pustules
Histology: ballooning degeneration, spongiosus (intra- and intercellular oedema), pustules, inclusion bodies, crust formation
37
Describe herpes virus dermatitis
Cats: felid herpes virus type I (FeHV-1)
Common pathogen of upper airways, but skin lesions often occur in absence of resp. signs
Primarily on nasal planum and haired skin of face
Persistent/recurrent crusts, ulcers and vesicles
Histology: ulcerative and necrotising dermatitis, large intranuclear glassy inclusion bodies and mixed dermal infiltration
38
Describe Malassezia dermatitis
Caused by the yeast Malassezia pachydermatis
Cats, dogs
Predisposing factors probably required (eg skin allergies)
Face, ears, ventral neck, axilla, medial legs
Erythema, alopecia, greasiness, lichenification (leathery skin), hyperpigmentation
Histology: parakeratotic (with nuclei) hyperkeratosis, epidermal hyperplasia, spongiosis. Mixed cell exocytosis. Aggregates of yeasts within crusts or S.corneum
Intensive pruritis
39
What is the causal agent of Malassezia dermatitis?
Yeast: Malassezia pachydermatis
40
Describe dermatophytosis
Superficial mycotic infection (ringworm), confined to the keratin layer of skin, claws, hair
Three main genera: Microsporum, Trichophytoa and Epidermophytoa
Favourable conditions: microabrasions/maceration of S.corneum in moist skin, prolonged corticosteroid treatment, immune deficiencies
Transmission: infected hair and keratin fragments. Fungi migrate to follicular lumen, proliferate along follicle
Circular expanding areas of scaling and alopecia. Often furunculosis and chronic pyogranulomas develop (kerion) and mimic tumours
Histology: ortho- and parakeratosis and acanthosis (increased thickness of S.spinosum). Luminal folliculitis, furunculosis and pyogranulomas
41
What is a fistula?
Draining tract
42
What is a mycetoma?
Tumour-like lesion characterised by tumefaction, draining tracts (fistula) and grains in the discharge
43
What are the 2 orders of Zygomycosis?
Mucorales (angioinvasion and dissemination)
| Entomophthorales (local subcutaneous granulomas)
44
Describe zygomycosis
Two orders: Mucorales and Entomophthorales
Caused by contaminated wounds and penetrating objects
Non-contagious
Trunk, neck, head
Solitary large ulcerated nodules with serosanguinous exudate and scattered yellow-white gritty masses (kunker)
Histology: thin-walled, occasionally septate and uncommonly branching hyphae within necrotic lesions surrounded by multifocal to diffuse eosinophilic and granulomatous inflammation
45
Describe Besnoitiosis
Caused by Besnoitia spp
Two host life cycle: Definitive=cat. Intermediate=variable, mainly cattle and horses
Causes large intracellular cysts in intermediate host species
46
Describe Leishmania
Obligate intracellular apicomplexan parasite of macrophages
Transmitted by blood-sucking sandflies
Two clinical forms:
Alopecic: stronger Th1 response, fewer parasites
Nodular: predominant Th2 response, more parasites
Head, limbs, dorsal midline
Gross lesion description: nodules, alopecia, ulcers or pustules
Histology: hyperkeratotic, nodular to diffuse superficial and deep granulomatous dermatitis, variably dominated by plasma cells
47
What is myiasis?
The infestation of living tissues by the larval stages (maggots) of dipterous flies
48
What causes Sarcoptic mange?
Sarcoptes scabiei
49
Describe sarcoptic mange
Caused by Sarcoptes scabiei
Zoonotic, highly contagious, notifiable
Extremely pruritic
Pigs and dogs
Inner surface of pinna, spreading to head, neck, legs
Life cycle is within tunnel burrowed under S.corneum -> scales and crusts
Histology: severe acanthosis (increased thickness of S.spinosum), ortho- and patchy parakeratosis, spongiosis, leukocyte exocytosis and eosinophilic pustules
50
Describe demodectic mange
Demodex mites are obligate parasites, life cycle is within the lumen of hair follicles and adnexa
Dogs
Alopecia, scaling and comedones in the squamous form; pustules, folliculitis and furunculosis in pustular form (with bacteria)
Localised form: well-circumscribed self-limiting lesions on ears, lips, eyes and extremities
Generalised form: diffuse alopecia and scaling on face and legs
Histology: severe suppurative folliculitis and furunculosis
51
What is a bruise?
The local effect of vigorous pressure (blunt trauma) can cause the occurrence of acute intradermal and/or subcutaneous haemorrhages
52
During the healing process of a bruise, what causes the bruises typical red colour to fade?
Erythrocyte removal (recruited leukocytes and phagocytes) and haemoglobin catabolism (haemoglobin red -> biliverdin green -> bilirubin yellow)
53
What is the difference between hypersensitivity and autoimmunity?
```
Hypersensitivity= excessive antibody production in response to an innocuous stimulus
Autoimmunity= pathological immune response against self-antigens
```
54
What may remain visible locally after clinical resolution of the trauma regarding a bruise?
Haemosiderin-laden macrophages
55
Describe Urticaria
Acute, variable pruritic, oedematous skin lesions- Type 1 hypersensitivity reaction
Caused by mediators of basophils and mast cells
Drugs, foods and food additives are frequent causes
Distribution= variable, from localised to widespread
Discrete, well-circumscribed, round erythematous and oedematous plaques
Histology: variable, non-specific. Subtle or prominent dermal oedema of the superficial dermis
Angioedema: larger, less demarcated swelling of deep dermis and subcutis
56
Urticaria is caused by mediators of what?
Basophils and mast cells
57
Describe atopic dermatitis
Increased production of IgE against 'innocuous' antigens
Prominent Th2 reactivity -> IgE hypersecretion and deficient cell-mediated immune response -> higher susceptibility to local infections
Very pruritic
Typically on ventral sparsely-haired skin
Excoriations, papules, pustules, hyper-pigmentation and lichenification are secondary to trauma induced by pruritis
Histology: perivascular to interstitial lymphoplasmacytic dermatitis with oedema, eosinophils, macrophages and variable degree of epidermal hyperplasia
58
Describe food allergy dermatitis
Exaggerated immune response against food allergens
Type 1 hypersensitivity
GI tract and skin
Similar to atopic dermatitis
Allergens are encountered in GI tract, and sensitised lymphocytes secondarily reach the skin
Non-seasonal severe pruritus, poorly responsive to corticosteroid treatment
59
Describe insect hypersensitivity
Antigens from insect saliva, venom, whole body or faeces
Type I and IV hypersensitivity reactions
Seasonal and pruritic
Flea-bite hypersensitivity= dogs and cats (FAD)
Culicoides hypersensitivity= horses (sweet itch)
Sparsely-haired body regions (lumbosacral-fleas)
Gross lesuion appearance: pruritic crusted papule -> hyperkeratosis, lichenification, seborrhea, excoriation
Histology: eosinophil-dominated dermal perivascular to diffuse dermatitis with lymphocytes
60
Describe skin autoimmunity
Pathological immune response against self-antigens -> production of autoantibodies
Uncommon
Several pathological theories:
-Drug can link with endogenous epidermal molecules -> immunogenic
-Infectious agents share sequence homology with some endogenous epitopes
61
Describe Pemphigus foliaceus
Autoantibodies against desmoglein 1 (cadherin family= calcium-dependent adhesion molecules; cell adhesion)
Lesions are restricted to skin (no mucosa)
Periocular and nasal skin -> ears, neck, ventral abdomen
Erythematous maculae -> pustules -> erosion and crusts
Histology: acantholytic subcorneal or intragranular pustular dermatitis
62
Describe Pemphigus vulgaris
Most severe and rare form
Autoantibodies against desmoglein 3, present on mucous membrane and mucocutaneous junctions
Lesion starts in mouth
Gross lesion appearance: fragile vesicle and bullae -> after rupture, erosion/ulcers
Histology: spongiosis and vacuolation of the suprabasilar layer -> vesicles and bullae above the basal layer. Mild superficial perivascular to interstitial dermatitis (inc. eosinophils)
63
Describe Bullous Pemphigoid
Autoantibodies against bullous pemphigoid antigen 1 (BPAG1) and 2 (BPAG2, only one recognised in animals)
Starts at oral cavity and mucocutaneous junctions -> face, groin, axilla,
Vesiculobullous, ulcerative and crusted lesions
Histology: subepidermal vesicles, bullae and ulcers containing neutrophils, eosinophils, other leukocytes. Mild mixed perivascular inflammation
64
What are the 2 forms of lupus eythematosus?
Systemic lupus eythematosus (SLE). Involvement of multiple organs with skin lesions in 1/3 affected animals
Discoid lupus eythematosus (DLE). Localised cutaneous form
65
Describe systemic lupus erythematosus
Immunoregulatory imbalance -> B cell hyperactivity
Autoantibodies against numerous antigens, mainly antinuclear antibodies against double-stranded DNA, RNA and histones
Main skin tissue damage is provoked by antigen-antibody cpmplexes (type III hypersensitivity)
Skin around eyes, mouth, nostrils, genitalia, perineal skin
Appearance varies from ulcerative to scaling and alopecia
Histology: lichenoid interface dermatitis. Apoptotic keratinocytes, pigmentary incontinence, hyperkeratosis, epidermal hyperplasia
66
Describe discoid lupus erythematosus
Localised form, most common in dogs
'Photosensitive nasal dermatitis'
Nasal planum only
Erythema, depigmentation, scaling, crusting, alopecia, ulcers
Histology: similar to SLE, but more epidermal hyperplasia, denser interface infiltrate dominated by lymphocytes
S. basale
67
What is satellitosis?
The abnormal clustering of one cell type around each other
68
Describe erythema multiforma
Uncommon, occurs with underlying conditions (eg drug therapy)
Type III and IV hypersensitivity reactions
Deposition of immune complexes in vasculature and basal membrane
Two forms:
-EM minor -> symmetrical bilateral erythematous papules and macules. Classical 'target' lesions
-EM major -> widespread mucosal lesions, extensive necrotising and vesiculobullous skin lesions and systemic illness
Histology: characteristic interface dermatitis with necrotic keratinocytes and satellitosis. Epidermal necrosis
69
Describe alopecia areata
Focal, multifocal or generalised asymptomatic inflammatory alopecia
Usually skin appears hyperpigmentated, hairs are short or fragmented (dystrophic)
Often spontaneously regresses and new hairs are white (leukotrichia)
Inflammation is restricted to hair bulb
Histology: peribulbar lymphocytic folliculitis -> pigmentary incontinence -> chronic lesions: telogen and atrophic follicles
70
What does lack of Vitamin A cause in skin?
Squamous epithelial hyperkeratosis (follicular keratosis)
71
What does lack of Vitamin E cause in skin?
Panniculitis due to steatonecrosis (lack of antioxidant protection)
72
What does lack of Vitamin B cause in skin?
Dry seborrhea with alopecia
73
Describe how a zinc deficiency affects skin
Important co-factor for many enzymes, inc those relates to DNA function
Pigs
D= symmetrical and bilateral on distal legs and around eyes, ears, tail
A= erythematous maculae -> papule covered in dry thick crusts
Histology: acanthosis and epithelial hyperplasia with para-keratotic hyperkeratosis, with prominent basal cell mitotic activity
74
Describe superficial necrolytic dermatitis
'Red, white and blue' epidermal disease: severe parakeratotic hyerkeratosis (red), spongiosis and oedematous spinous layer (white) and basal layer hyperplasia (blue)
Highly associated with glucagon-secreting pancreatic tumours and end-stage liver disease
D= bilateral and symmetrical on lips, periocular skin, pinna and distal extremities
A= areas of erythema, erosion, ulcers, crusts
75
What causes Cushing's disease?
Hyperadrenocorticism (pituitary gland tumour, adrenal tumour or iatrogenic administration)
76
Describe Cushing's disease
Hyperadrenocorticism (pituitary tumour, adrenal tumour or iatrogenic administration)
No pruritis
Calcinosis cutis due to corticosteroid treatment (calcium deposits in skin)
A & D: bilateral and symmetrical hypotrichosis (sparse hair) and alopecia of trunk, abdomen. Skin is diffusely thinned and less elastic. Hyperpigmentation, comedones (blackheads), calcinosis cutis
Histology: diffuse cutaneous atrophy with ortho-keratotic hyperkeratosis and follicular keratosis
77
What are the causes of hyper-oestrogenism in female and male dogs?
Female: polycystic ovaries, functional ovarian neoplasms
| Intact males: oestrogen-secreting tumours (sertoliomas)
78
Describe an eosinophilic plaque
Cats
Pruritic lesion associated with hypersensitivity
Haired skin of inguinal, axillary, lateral thigh areas
Diffuse and perivascular eosinophilic dermatitis, with epidermal acanthosis and spongiosis
79
Describe an eosinophilic granuloma
Cats
Raised, pink, variable pruritic nodular lesions on both haired skin (linear) and oral mucosa (nodular)
Diffuse eosinophilic inflammation with granulomas centred around degenerated collagen bundles covered with degenerate and degranulating eosinophils (flame figures)
80
What is meant by a 'flame figure'?
Degenerate and degranulating eosinophils
81
Name 3 feline eosinophilic dermatoses
```
Eosinophilic plaque (legs)
Eosinophilic granuloma (mouth)
Indolent ulcer (lips)
```
82
Name 3 equine eosinophilic nodular diseases
Collagenolytic granuloma
Axillary nodular necrosis
Unilateral papular dermatosis
83
Describe collagenolytic granuloma
Horses
Single/ multiple nodular, NON-PAINFUL, NON-PRURITIC lesions
Foci of collagen degeneration surrounded by granulomas, sometimes with macrophage palisading and numerous eosinophils
84
Describe axillary necrosis
Horses
Nodular, NON-PAINFUL, NON-PRURITIC lesions on trunk behind axilla (girth galls)
Foci of coagulative necrosis with numerous eosinophils and fewer flame figures (may be eosinophilic vasculitis)
85
Describe unilateral papular dermatosis
Horses
Seasonal, uncommon unilateral nodules on lateral trunk
Small foci of folliculocentric coagulative necrosis
86
Tumours of the epidermis are derived from which cells?
Keratinocytes
87
Describe an epidermal cyst
Single dermal mass, not neoplastic
Filled with lamellar keratin, lined by continuous squamous epithelium
Cause:
-Enormous abnormal distention of follicles
-Traumatic dermal implantation of epidermal fragments (rare)
88
Of epithelial and follicular tumours, which are more often malignant?
Epithelial
89
How may a papillomavirus infection facilitate the progression of UV light-induced neoplasia?
By inhibition of DNA repair and apoptosis, and by inducing proliferation
90
What are koilocytes?
Keratinocytes with eccentric pyknotic nucleus (condensation of chromatin in nucleus) and peripheral clear halo (ballooning degeneration)
91
Describe papilomas
Epithelial proliferation induced by host- and site-specific Papillomaviruses
Immune system competence linked to susceptibility and regression
Cutaneous papillomas: one/multiple filiform exophytic and hyperkeratotic projections of epidermis, supported by thin dermal stalks (S.spinosum and granulosum)
Fibropapillomas: plaque-like lesions with predominant dermal proliferation (eg Sarcoids)
Single/multiple, bleed easily ->secondary infections
92
Dscribe squamous cell carcinoma
All domestic species
Locally invasive and destructive (rarely metastatic)
UV light directly involved in white/pale animas. Viral papillomas can be predisposing condition
A: singe expansile hyperplastic ulcerated or nodular skin lesions
D: mainly on head
Histo: invasive islands and cords of neoplastic cells within dermis. Anisocytosis, anisokaryosis and mitotic index are high. Keratin pearls. Inflammation and desmoplasia. Neutrophilic pustules due to abnormal keratin formation and necrosis
93
Describe basal cell tumours
Older cats and dogs
Tumours arise from S. basale
Classified as basal cell carcinoma when malignancy is present without differentiation towards sebaceous gland or follicular wall epithelium
May have connection with superficial epidermis
Head and neck of cats
May recur locally but no metastasis
Histo: cells resembling basal cells. Cords and sheets with indistinct cell boundaries extend into dermis. Cells with small hyperchromatic nuclei and high mitotic index. Desmoplasia
94
Describe the types of follicular tumours
Classified according to segment of origin, as assessed by differentiation pattern observed:
- Infundibular differentiation with keratohyalin granules in granular layer: Infundibular keratinising acanthoma
- Clear keratinocytes similar to the isthmic outer root sheath cells: Tricholemmoma
- Signs of matrical differentiation as seen in hair bulb: Pilomatricoma
- Characteristic of all 3 segments: Trichoepithelioma
- Formation of primitive hair germ cells: Trichoblastoma
95
Describe an infundibular keratinising acanthoma
Single intradermal 0.5-3cm exophytic mass
Central lumen filled with keratin and central pore
Lined by squamous epithelium, only moderately anaplastic
Surrounded by compressed collagen and moderate inflammation
96
Describe a tricholemmoma
```
Benign neoplasm originating from the external root sheath of the hair follicle
Clear keratinocytes (isthmic outer root sheath cells)
Central cells with abundant deep eosinophilic cytoplasm (inferior type)
Central tricholemmomal keratinisation (isthmic type)
```
97
Describe a pilomatricoma
Solitary benign tumour, localised to the lower dermis and subcutis
Derived from follicular matrix cells
Chalky white on cut surface, multiobulated and sometimes pigmented
Central portion abruptly filled with 'ghost cells' (pale eosinophilic anucleated cells)
Common mineralisation
98
Describe a trichoepithelioma
Multilobulated intradermal mass
| Trichogenic differentiation to all 3 segments of the hair follicle
99
What are the 4 histological types of trichoblastoma (formation of primitive hair germ cells)
Spindle type
Ribbon type
Granular type
Trabecular type
100
Describe the 3 types of sebaceous gland tumours
Most common in dogs
Adenoma: well-differentiated, well-demarcated, preponderance of sebocytes, few basaloid cells and ducts
Epithelioma: preponderance of basaloid cells, few sebocytes and ducts. Intermediate degree of malignancy
Adenocarcinoma: cells with variable degree of sebaceous differentiation
-Irregular lobular formations
-Pleomorphism, high mitotic index -> few sebocytes
-Local infiltration -> regional lymph nodes -> lungs?
101
Describe perianal gland tumours
Mae dogs, 8+yrs
Castration causes regression in most cases
Solitary/multiple nodular masses, up to 10cm diameter, can ulcerate
Microscopically consist of chords of large acidophilic polygonal 'hepatoid' cells surrounded by reserve cells. Mitoses of reserve cells, ulcerations, necrosis
Hepatoid gland adenoma:
- Compact well-organised lobules
- Low pleomorphism
- Well demarcated
Hepatoid gland carcinoma
- Disorganised lobular pattern
- Higher cellular atypica and mitotic index
- Local invasion
102
Describe sweat gland tumours
Middle aged dogs
Adenoma of apocrine glands:
- Gross: well-circumscribed, grey/tan, solid/cystic
- Histo: well-circumscribed, non-encapsulated dermal nodule formed by multiple cystic tubules lined by well-polarised cuboidal-columnar epithelium, papillary ingrowths
Carcinoma of apocrine glands:
- Gross: less circumscribed and ulcerated
- Histo: poorly differentiated, desmoplasia, anaplasia, invasion, metastasis
103
Why are ceruminous gland tumours more common in cats?
Horizontal ear canal
104
Describe ceruminous gland tumours
Cats (horizontal ear canal)
| Grossly: present as obstructive, ulcerated, nodular or pedunculated masses, the cut surface exhibiting a yellow colour
105
What does vitamin D stand for with respect to describing lesions?
```
Vascuar
Inflammatory
Trauma and chemicals
Autoimmune
Metabolic and hormonal
Idiopathic
Neoplastic
Developmental and Degenerative
```
106
Describe a fibroma
Single intradermal or SC mass, often raised. On cut section: well-circumscribed, non-encapsulated, white to grey derma nodules
Resemble normal mature fibrocytes in interwoven fascicles with abundant collagen production
Excision is curative
107
Equine sarcoids are which kind of skin tumour?
Fibroblastic
108
What are the 3 predisposing factors for equine sarcoids?
Genetic predisposition, trauma, virus (bovine papillomavirus 1 and 2)
109
Describe equine sarcoids
Unique, locally aggressive fibroblastic skin tumour
3 predisposing factors: trauma, genetic predisposition, virus (bovine papillomavirus 1 and 2)
Don't metastasise
Recur following surgery
Can be occult (alopecic plaque), nodular or mixed verrucous/fibroblastic (wart-like)
Biphasic tumour: both an epidermal and dermal component (although predominantly connective tissue)
Hist: resemble fibromas/low-grade fibrosarcomas.
Neoplastic cells are haphazardly arranged in streams of spindloid cells. Cells show poorly demarcated cytoplasmic borders, faintly eosinophilic cytoplasm. Moderate pleomorphism
110
Describe fibrosarcoma
Occur anywhere in skin and subcutis of older dogs and cats
| Variable degree of differentiation, rapid infiltrative growth, often recur after removal, metastasis in
111
Describe post-vaccinal fibrosarcomas
Cats only
Locally invasive spindle cell sarcoma occurring at site of previous vaccinations
Difficult to cure
Lymphocytic infiltration and remnants of vaccine-induced panniculitis with multinucleated giant cells scattered at periphery of neoplasia
112
Describe myxoma/myxosarcoma
Tumours originating from primitive pleomorphic fibroblasts, characterised by their abundant myxoid matrix rich in muco-polysaccharides (glycoaminoglycans)
Locally aggressive malignant tumours
Loosely arranged stellate or spindle cells separated by mucinous stroma
113
Describe canine haemangiopericytoma
Neoplastic entity in dogs aged 8-14yrs
Boxer, Springer Spaniel, German Shepherd
Firm to soft, fluctuant, nodular growth, rarely ulcerates, up to 10cm diameter, slow-growing, may be locally infiltrative but rarely metastasises
Formed from pericytes around capillaries
Histo: 'whorling' palisade-like fingerprint pattern, sometimes surrounding small capillaries
FL and HL
Non-encapsulated, well-circumscribed dermal or SC nodule formed by the confluence of dilated blood-filled channels lined by flattened endothelium
114
Describe a lipoma
Benign tumours of adipose tissue
Encapsulated by a thin fibrous capsule
Common in dogs: older, obese females, trunk and proximal limbs
Excision is curative
115
Describe a haemangiosarcoma
More common in older dogs
Grow rapidly
Skin and soft tissues
Distant metastasis (lungs and liver)
Cutaneous haemangiosarcomas less aggressive than visceral
Only clue for morphological recognition= occasional cleft-like spaces
Pleomorphic and plump hyperchromatic spindle cells, vascular channel formation
116
Describe infiltrative lipomas
Rare in dogs; middle-aged females, thorax and limbs
Difficult to remove completely as they dissect along fascial planes and between skeletal muscle bundles
Aggressive excision is recommended, amputation may be necessary
117
IHC anti-CD18 is involved in what?
What are they considered markers of?
Which tumours are they associated with?
Adhesion and migration of inflammatory cells through activated blood vessels
Markers of monocytes/macrophages
Liposarcomas
118
What are Langerhans cells?
Type of WBCs
119
Histiocytoses usually involve which cell type?
Langerhans cells
120
Benign systemic histiocytosis affects which dog breed?
| Where are they found?
Young Bermese Mountain dogs
| Skin and lymph nodes; scrotum, nose, eyelids
121
Mastocytomas (mast cell tumours) affect which dog breeds?
Boxer, Boston terrier, Labrador
| Older dogs
122
What do mast cell tumours present as?
| Which skin layers are they found in?
Subcutaneous nodules, occasionally as oedematous swellings
| Usually localised to dermis, may extend to subcutis and musculature
123
Which cells are found in mastocytomas?
```
Mast cells (contain metachromatic granules)
Eosinophils
```
124
Mastocytomas are what grade of tumour?
Grade I
| Lower malignancy, longer survival times
125
Briefly describe the 3 grades of cutaneous mast cell tumours
Grade I: well-differentiated, uniform cells, no giant cells, obvious cytoplasmic granules, uniform nuclei, low malignancy
Grade II: intermediate differentiation, moderate anisocytosis, few giant cells, visible cytoplasmic granules, anisokaryosis, medium malignancy
Grade III: poor differentiation, marked anisocytosis, frequent giant cells, inconspicuous/absent cytoplasmic granules, anisokaryosis, high malignancy
126
Where are extra-medullary plasma cell tumours found?
Head and extremities of older dogs
127
What are the two forms of cutaneous malignant lymphoma?
```
Epitheliotropic form (involving epithelium)
Nodular, non-epitheliotropic form
```
128
What is the most common form of cutaneous lymphoma in dogs?
Epitheliotropic cutaneous (malignant) lymphoma
129
Epitheliotropic cutaneous (malignant) lymphomas are diagnosed as what?
Epitheliotropic T cell lymphoma
130
Of epitheliotropic and non-epitheliotropic (malignant) lymphoma, which is more aggressive?
Non-epitheliotropic
131
Non- epitheliotropic cutaneous (malignant) lymphomas are diagnosed as what?
Cutaneous B cell lymphoma
132
Melanocytic tumours are common in which kind of dogs?
Darkly pigmented breeds eg Kerry Blue
133
Where are melanocytic tumours usually found?
Face, trunk and extremities
| Also gums, oral mucosa, palate and lips
134
Are oral melanomas usually benign or malignant?
Malignant
135
Are cutaneous melanotic tumours in dogs usually benign or malignant?
Benign, except if on digits or scrotum
136
What is the best indicator of malignancy when looking at tumours?
Mitotic figures
137
Regarding melanomas, are poorly melanotic or very melanotic tumours more malignant?
Poorly melanotic/amelanotic
138
Briefly describe malignant melanomas
Amelanotic, exhibit greater pleomorphism, giant cells, mitoses
Commonly metastasise to regional lymph nodes and lungs
139
Which types of tumours have the greatest metastatic potential?
Mammary gland adenocarcinomas, squamous cell carcinomas, transitional cell carcinomas, pulmonary adenocarcinomas and angiosarcomas
140
What should you do if a cat has multiple carcinomas on their feet and why?
Check for a lung tumour, as in cats, pulmonary adenocarcinomas preferentially metastasise to the distal extremities
141
Calcinosis circumscripta (tumoral calcinosis) localises where?
Bony prominence
142
Describe the early and chronic lesions of Calcinosis circumscripta
Early: fluctuant, chalky white -> dermal lakes of von Kossa positive material surrounded by inflammation and fibrosis
Chronic: lesions are firmer -> more mineralised and fibrotic -> osseous or cartilaginous metaplasia can occur
143
Where are lesions from herpes virus dermatitis primarily seen and in which species?
Cats
| Nasal planum and haired skin of face
