Skin Flashcards
Intertrigo
Skin Fold Pyoderma
Plaques
Coalesced papules
Pustule
MDx
Grade II soft tissue sarcoma
Pathogenesis of sarcoptic mange
- Burrow into stratum corneum
- Intesnse pruritis through hypersensitivity mechanism
- Self trauma, chronic irritation
- Hyperkeratosis, lichenification, alopecia
Portals for bacterial infection of skin
Pores - Follicular Openings
Hematogenous Spread
Direct entry through damaged skin
Histological appearance of callus
Epidermal hyperplasia
Subcorneal Vesicle
Stratum corneum forms the roof of the vesicle
Pyoderma
Clinical term encompassing several diseases
“Pus in the skin”
Usually bacterial infection involved
Disease and Cause
Impetigo - Superficial Pyoderma
Bacterial infection secondary to immunosuppression/debilitation
Purpura hemorrhagica
Red or purple macules or patches (hemorrhage or infarct) in the skin or mucous membranes
Disease
Arabian Fading Syndrome
Vesicle / Bulla
Palpable elevation filled with clear fluid
Vesicle - < 1cm
Bulla - > 1cm
Mdx
Cutaneous Infarcts
Disease and Cause
Purpura hemorrhagica
Streptococcus equi
Wheal
Elevated, irregular shaped area of cutaneous edema, solid, transient
Disease
Histiocytoma
Idiopathic Sterile Granuloma and Pyogranuloma Syndrome
Rare
Cause unknown
Diagnosis of exclusion
Mdx
Papular dermatitis
Pathogenesis of purpura hemorrhagica
Type III hypersensitivity immune mediated vasculitis
Albinism
Melanocytes present but defect to synthesize melanin; color dilution is a mild form
Vesicle / Bulla
Acantholysis
Disruption of intercellular junctions
Disease
Puppy Strangles
Arabian Fading Syndrome
Horses with vitiligo
Mdx
Multifocal cutaneous edema and congestion
Secondary hyperkeratosis can be due to
Endocrine imbalances
Chronic dermatitis
Zinc responsive
Mdx
Vesiculo-ulcerative dermatitis
Ulcer
Mdx
Generalized subcutaneous edema
Discoid Lupus Erythematosis
Induction/ exacerbation by UV light
Dorsal nose and nasal planum, pinnae, lips, periocular resion, oral mucosa
Spongiosis
Intercellular Edema
Histologic characteristics of allergic skin disease
Lymphocyte and eosinophillic dermatitis
Pathogenesis of Squamous Cell Carcinoma
Solar radiatoin, chronic injury commonly involved
Ulcer
Loss of epidermis with exposure of dermis
Frost bite
Lesions in cold exposed extremiteis
Caused by exposure to cold temperature
Pathogenesis of Primary Idiopathic Seborrhea
Thought to involve hyperproliferation of the epidermis, hair follicle infundibulum and sebaceous gland
Disease
Insect bite hypersensitivity
Diagnostic technique used for opportunistic mycobacteriosis
Culture and Sensitvity
Cause of ulcers
Secondary to:
Epidermial necrosis
Inflammation
Infarction
Neoplasia
Callus
Proliferative lesions are associated with what type of disease
Viral
Hemangioma - Hemangiosarcoma
Young adult dogs
Due to solar radiation
Pustules and Crust are indicative of what pathological process
Inflammation and Repair
Mdx
Ulcerative dermatitis
Hyperkeratosis
Increased thickness of stratum corneum
Scaling “seborrhea”
Primary Vs Secondary
Disease
Fungal dermatitis
Pyotraumatic Dermatitis
Hot Spots
Very common in dogs
Moist, alopecic, slighly raised red well circumscribed lesions that lead to ulceration and crusting
Disease
Papilloma
Disase
Lipoma
Pathogenesis of primary photosensitization
- UV Light absorbed by photodynamic chemicals in the skin
- Free radical damage
- Epidermal necrosis of lightly pigmented or sparsely haired skin
Calcinosis cutis
Associated with hyperadrenocorticism
Erythematous to white gritty plaques and nodules
MDx
Exudative dermatitis
Pustule
Palpable elevation filled with pus
Disease
Discoid Lupus Erythematosis
T/F: Degenerative/Necrotic lesions are the only pathological processes that cause ulceration
False
Later gross features of dermatitis
Scaling
Ulceration
Alopecia
Lichenification
Pigmentary change
Fibrosis/scarring
Pathogenesis of Erythema Multifome and Toxic Epidermal Necrolysis
Thought to involve type IV hypersensitivity towards antigens or the surface of keratinocytes inducing apoptosis
Histological appearance of equine sarcoid
Composed of both epithelial and dermal components - need biopsy that is not ulcerated to diagnose
Cause of Canine Leproid Granuloma
Saprophytic mycobacteria
Mdx
Multifocal cutaneous ecchymotic hemorrhages
Acral Lick Dermatitis
Lick Granuloma
Common in dogs
Extremities - circumscribed, hairless, and ulcerated
Disease and cause
Sarcoptic Mange
Sarcoptes scabiei
Pattern
Eosinophilic granuloma complex
Causes of fungal dermatitis
Pythium
Lagenidium spp
Chemical Burns
Caused by body or wound secreations, application of drugs, exposure to acids, alkalies, soaps, detergents, or irritant plants
Diagnose Canine Leproid Granuloma
Histopathology
PCR- if needed
____________________________
Difficult to culture
MDx
Multifocal exudative dermatitis
Nodule
Causes of scale
Disorders of keratinization
Chronic dermatitis
Disease
Zinc Responsive Dermatosis
Equine Sarcoid
Common in young adult horses
Frequently involve sites of previous wounds
Invasive, high rate of recurrance, but do not metastasize
Variable range from nodular to plaque like to wart like
Gross appearance of Discoid Lupus Erythematosis
Depigmentation
Erythema
Scaling
Erosion
Ulceration
Crusting
Disease
Actinomycete Mycetomas
Localized Hyperpigmentation
Chronic inflammation or physical irritation
Congenital
MDx
Eosinophillic and granulomatous dermatitis
MDx
Chronic Dermatitis
Cause of demodicosis
Demodex spp mite
MDx
Neutrophilic / exucative dermatitis/folliculitis
Disease
Equine Sarcoid
Characteristics of skin lesions caused by circulatory disorders
Discrete reddened areas
Lesions follow a linear pattern
Lesions are in geometrical shapes
Vascular lesions result in ischemia
Granulomatous lesions are associated with what type of diseases
“Higher” Bacteria
Mycobacteria
Fungal
Foreign Substance
Acanthosis
Increased thickness of stratums basale and spinosum
Disease
Intertrigo
Cause of Sarcoptic Mange
Sarcoptes scabiei
Disease
Sebacious Adenoma
Histologic feature of solar/actinic keratosis
Dermal Elastosis
Cause of acral lick dermatitis
Persistant chewing or licking
Hypopigmentation - Hypomelanosis
Melanocytopenic (decreased melanocytes) vs Melanopenic (decreased melanin)
Congenital vs Acquired
Generalized form of demodicosis
Familial with young dogs
Adult onset - associated with systemic disease such as neoplasia, endocrinopathy or immunosuppresive therapy
MDx
Pustular Dermatitis
Lichenification
Thickening and hardening of the skin
Causes of eosinophilic granulomas
Parasite infection
Insect bite hypersensitivity
Foreign body reaction
Pathological processes that could cause ulcers
Degeneration/Necrosis
Inflammation and Repair
Circulatory Disorders
Disorders of Growth
Calcificaion of skin
Most common forms observed int he skin are both classified as dystrophic calcification
Chalky white, gritty to hard texture
Calcinosis cutis vs Calcinosis circumscripta
MDx
Pyogranulomatous dermatitis
Early gross features of dermatitis
Edema
Erythema
+/- pustules, crust vesicles
Plaque
Tissue Pigment
Melanin
Disease
Hypopigmentation
_______________________
Albinism
Indolent Ulcer
Ulcers on upper lips
Solar/Actinic Keratosis results in an increased risk for
Neoplasia due to direct DNA injury and subsequent mutations
Characteristics of canine melanomas
Oral, mucocutaneous, subungual lesions are typically malignant
Lesions on haired skin are often benign
Why are bacterial skin infections common in dogs?
Thin stratum corneum
Lack of lipid seal of hair follicles
High skin pH
Most degeneration and necrosis skin cases have what features
Bacterial infection
Epidermal necrosis/ulceration
Leukocyte infiltrate
Thrombosis
Predisposing factors for dermatophilosis
Wet weather in humid climates (“rain rot”)
Prolonged wetting of skin/hair/wool allows penetration of epidermis by zoospores
Type II (Intrinsic) Photosensitization can be caused by
Porphyria
Inherited deficiency of proporphyrinogen III cosynthetase
Defect in heme synthesis
Buildup of porphyrins
Gross lesion progression from solar injury
Erythema → Blistering/Vesicles → Sloughing of necrotic skin
MDx
Pustular to exudative dermatitis
Gross appearance of insect bite hypersensitivity
Often includes papules
MDx
Ulcerative/Exudative dermatitis
Disease
Acral Lick Dermatitis
Scale
Diagnosis of fungal dermatitis
Cultrue and PCR
Hydropic Degeneration
Intracellular Edema
Fungal Dermatitis
“Swamp Cancer”
Uncommon
Clinically resembles neoplasia… invasive lesions, involvement of regional lymph nodes
Greasy Form (Seborrhea oleosa)
Excessive brown to yellow lipids
Angioedema involves what layers of the skin
Dermis and Subcutis
What secondary condition is commonly associated with flea bite hypersensitivity
Pyotraumatic dermatitis - secondary to self trauma associated with pyoderma
Disease
Cutaneous Soft Tissue Sarcoma
Squamous Cell Carcinoma
Verrucous and ulcerated
Poorly pigmented, sparsley haired, sun exposed areas
Type III Hypersensitivity
Immune complex mediated hypersensitivity
Manifestation - localized arthus reaction and generalized reactions such as serum sickness, necrotizing vasculitis and glomrulonephritis
Disease
Epitheliogenesis Imperfecta
Histological appearance of acral lick dermatitis
Not really a granuloma!
Epidermal hyperplasia
Granulation tissue
Fibrosis
Type I Hypersensitivity
IgE mediated hypersensitivity
Typical manifestation - systemic anaphylaxis and localized anaphylaxis
Allergy
Stain used to detect fungal dermatitis
GMS Stain
Infarcts
Sharply demarcated geometrical shaped dark red to blue area
Becomes firm, dry, sunken, darkened - features of necrosis predominate
Mdx
Cutaneous calcification
Mdx
Chronic dermatitis and cutaneous hyperpigmentation
______________
D/t chronic flea allergy dermatitis
Mdx
Dermal fibrosis and epidermal hyperplasia