Unit 2- Skin Flashcards
Vitamin D Production
Epidermis converts provitamin D3 into D3, liver hydroxylates, and kidneys convert to active form
Lesion Characteristics
Distribution, location, size, shape, configuration, type
Primary Lesion
Directly associated with disease process
Secondary Lesion
Modification of the primary lesion that results from its evolution or traumatic injury
Macule
A smaller flat circumscribed lesion of altered skin color
Patch
A larger flat circumscribed lesion of altered skin color
Papule
A small solid elevated lesion
Plaque
A larger flat elevation in skin
Pustule
Circumscribed raised superficial accumulation of purulent fluid within the epidermis
Vesicle
A smaller sharply circumscribed elevation of epidermis filled with clear fluid
Bulla
A larger sharply circumscribed elevation of epidermis filled with clear fluid
Wheal
Sharply circumscribed raised lesion consisting of edema
Nodule
Circumscribed larger solid elevation that usually extends into deeper layers of skin
Cyst
Epithelium lined cavity containing fluid or solid material, smooth, well circumscribed, solid mass
Alopecia
Partial to complete loss of hair
Scale
Sheets of cornified cells that split and separate from epidermis as fragments
Crust
Desquamation composed of dry accumulations of serum, pus, epithelial, and bacterial debris
Follicular Casts
Accumulation of keratin and follicular material that adheres to the hair shaft extending above the surface of the follicle
Comedo
Dilated hair follicle filled with cornified cells and sebaceous material
Epidermal Collarette
Thin layer of scale that expands peripherally and forms a ring
Scar
Fibrous tissue that replaces normal skin after dermis injury
Excoriation
Superficial linear break of the dermis
Erosion
Partial-thickness loss of epidermis resulting in shallow, moist, glistening depression
Ulcer
Full-thickness loss of epidermis and basement membrane, portion of dermis with depression and exposed surface
Fissue
Deep linear break from epidermis into dermis
Lichenification
Rough, thickened epidermis
Callus
Thick, firm, hyperkeratotic, hairless plaque with increased skin folds, wrinkles, or fissures
Superficial Skin Scraping
Scabies mite
Deep Skin Scraping
Demodex mite
Tape Cytology
Bacteria, yeast, acantholytic cells
Cytology for masses
Fine needle aspirate
Culture of Superficial Infections
Skin swab for aerobic bacteria
Culture of Deep Infection
Sterile tissue culture for bacteria, mycobacterium, and fungi
Dermatophyte Culture
Hair pluck, toothbrush, dermatophyte test medium, and PCR
Allergy Testing
Serology or intradermal testing only after all other causes of pruritus have been ruled out
When to biopsy
Disease can only be diagnosed by biopsy, failure to respond to therapy, severe clinical presentation, persistent ulcer, nodular or neoplastic, and guides treament
What to biopsy
Primary lesions
Prior to biopsy
Avoid steroids, treat infection, submit tissue culture, leave crusts and scales, provide clinical history and differentials
Keratinocyte Function
Permeability barrier, structural support, immunoregulation
Keratinocyte Structure
Keratin filaments connect to desmosomes, providing structural integrity
Lamellar body
Lipid vesicles that act as structure between keratinocytes
Hyperkeratosis
Excessive thickening or hyperplasia of stratum corneum
Primary cause of hyperkeratosis
Mutation of lipids, enzyme, or structural protein
Secondary cause of hyperkeratosis
Chronic irritation
Orthokeratosis
Keratinocytes undergo complete cornification and lose their nucleus
Parakeratosis
Keratinocytes only partially undergo cornification due to faster turnover time and retain the nucleus
Golden Retriever Ichthyosis
Lamellar othokeratotic hyperkeratosis, congenital defect in formation of the stratum corneum leading to generalized scaling on the trunk
Primary Serborrhea
Excessive scaling, not a diagnosis
Acanthosis
Epidermal hyperplasia, thickening due to increased number of cells in the epidermis, especially stratum spinosum, response to chronic inflammation
Acral Lick Dermatitis
Underlying disease causes chronic focal trauma and secondary deep pyoderma on dorsal carpus of dog
Spongiosis
Intercellular Edema
Intracellular Edema
Ballooning degeneration in the superficial layer, hydropic degeneration in the basal layer
Acantholysis
Disruption of desmosomes between keratinocytes, causes vesicles and bullar
Subcorneal Acantholysis
Superficial layer, pemphigus foliaceus
Suprabasal Acantholysis
Basal layer, pemphigus vulgaris
Exocytosis
Aggregation of leukocytes in the epidermis
Langerhans Cells
Immune dendritic cells that process and present antigens to T cells
Contact Hypersensitivity
Allergic contact dermatitis, hapten delayed hypersensitivity
MElanocytes
Transfer melanin to keratinocytes in basal cell layer of epidermis and anagen hair follicles
Pigmentary Incontinence
Loss of melanin due to damage to the cells of the basal layer or follicles, causes accumulation of pigment in macrophages
Lentigo Simplex
Black spots on cat face, permanent but harmless
Uveodermatologic Syndrome
Autoimmune disease attacking melanocytes and causing uveitis, photophobia, blepharospasm, and depigmentation in akita and arctic breeds
Merkel Cells
Mechanoreceptors in tylotrich pads and hair follicles
Basement Membrane Zone
Anchors epidermis to dermis and heals wounds
Subepidermal Blistering Disease
Vesicles lead to ulcers and subepidermal cleft under the basement membrane
Ehlers-Danlos Syndrome
Congenital defect in dermal collagen leads to cutaneous hyperextensibility, tears, wounds, and scars, diagnosed by skin extensibility index
Solar Dermatitis
Chronic exposure to light alters fibroblast function and causes erythema, scales, thick skin, erosions, ulcers, comedones, and cancer
Calcinosis Cutis
Hypercortisolemia causes dermal mineralization on the dorsal neck, axilla, and groin
Simple Follicles
Human, cattle, horses, pigs
Compound Follicles
Dogs, cats, sheep, goats
Hair Growth Cycle
Anagen is the growth phase, telogen is resting phase when the follicle retracts into the dermis
Sinus Hairs
Slow adapting mechanoreceptors
Tylotrich Hairs
Rapid adapting mechanoreceptors scattered among normal hair
Anagen Stimulating Hormones
Thyroid hormone and androgens
Anagen Inhibiting Hormones
Glucocorticoids and estrogen
Adnexal Atrophy
Endocrine dermatopathy, alopecia
Sebaceous Glands
Holocrine glands open into the hair follicle
Sebaceous Adenitis
Loss of sebaceous glands and replacement with inflammatory cells leads to scales, hair thinning, alopecia, and follicular casts in poodle, akita, samoyed, and vizsla
Epitrichial Sweat Glands
Apocrine glands empty into the hair follicle
Atrichial Sweat Glands
Eccrine glands present in paw pads empty directly onto the skin
Subcutis
Adipose tissue and loose connective tissue between dermis and muscle
Panniculitis
Inflammation of the panniculus (subcutis)
Perivascular Dermatitis
Inflammatory cells aggregate around blood vessels due to any insult
Superficial Perivascular Dermatitis
Due to hypersensitivity disorders
Type I Hypersensitivity
After first hypersensitivity, IgE will bind mast cells to release cytokines that attract eosinophils and lead to second reaction
Acute Perivascular Dermatitis
Edema, erythematous papules
Chronic Perivascular Dermatitis
Alopecia, lichenification, and hyperpigmentation
Urticaria
Smaller hives
Angioedema
Larger hives
Canine Atopic Dermatitis
Generalized pruritus due to skin barrier dysfunction and dysregulated immune response leads to secondary infection, lesions, diagnosis by allergy testing
Canine Food Allergy
Non seasonal pruritus, GI signs, and secondary infection
Canine Flea Allergic Dermatitis
Seasonal hypotrichosis, papules, erythematous plaques, and wheals due to sensitization to flea saliva proteins
Feline Atopic Skin Syndrome
Inflammatory and pruritic skins syndrome of cats manifested by nonspecific reaction patterns
Cutaneous Reaction Patterns for FSS
Miliary dermatitis, self-induced alopecia, face head neck pruritus, and eosinophilic granuloma complex
Sarcoptic Mange
Burrowing mites cause highly contagious pruritus, diagnose with scraping
Cutaneous Acariasis
Intracorneal arthropods
Malassezia Dermatitis
Secondary yeast infection concurrent with otitis externa
Armadillo Westie
Malassezia dermatitis in west highland white terriers
Parakeratosis
Indicative of increased epidermal turnover
Type 1 Zinc Responsive Dermatitis
Defect of Zn absorption or metabolism in husky and malamute
Type 2 Zinc Responsive Dermatitis
Zinc deficient diet or over supplementation of chelates
Zinc Responsive Dermatosis in Pigs
Piglets not allowed access to soil or not supplemented with zinc
Superficial Necrolytic Dermatitis
Liver disease, glucagonoma, or diabetes causes hyperkeratosis of paw pad, bilaterally symmetrical erythemal, scaling, crusting, erosion, and ulcer in small breed geriatric dogs
French Flag Histology
Red (parakeratosis), white (edema), and blue (basal cell hyperplasia) in superficial necrolytic dermatitis
Interface Dermatitis
Type III or IV hypersensitivity targets basal keratinocytes and dermoepidermal junction
Acantholysis
Loss of cohesion between keratinocytes due to desmosome breakdown
Acantholytic Cells
Keratinocytes separate from neighbors and become rounded
Intraepidermal Vesicular Dermatitis
Caused by acantholysis, vesicles and pustules form and progress to erosions and crusts
Cause of Acantholysis
Pemphigus foliaceus, S. pseudintermedius, Dermatophytes release proteolytic enzymes
Pemphigus Foliaceus
Type II hypersensitivity, autoantibodies against desmocollin 1, pustules, erosions, and crusting on face, ears, and paw pads, subcorneal pustule
Pemphigus vulgaris
Suprabasal vesicles and bullae progress to erosions and ulcers in oral cavity, mucocutaneous junction, and sin, caused by autoantibodies against desmoglein-3
Impetigo
Puppy pyoderma, cutaneous abrasions or immunosuppresion allows S. pseudintermedius to invase, pustules on ventral abdomen and perineum
Porcine exudative epidermitis
Greasy pig disease, S. hyicus produces exotoxins that cause intra-epidermal cleavage and pustules and crusting
Dermatophilosis
Rain rot, Dermatophilus congolensis causes thick yellow-brown keratinized crust with skin trauma and prolonged moisture in livestock
Subepidermal Vesicular Dermatitis
Subepidermal blistering disease, poor prognosis and difficult to treat
Subepidermal Blistering Disease Causes
Congenital defect in structural proteins, autoantibody targeting antigens of basement membrane
Congenital epidermolysis bullosa
Congenital defect in structural proteins of basement membrane and cytoskeleton of basal keratinocytes
Congenital epidermolysis bullosa signs
Vesicles, erosion, ulcer, sloughing of skin, nail, or hooves on skin, oral cavity, extremities, and paw pad
Mucous Membrane Pemphigoid
Ulcers in oral cavity, nasal, periocular, and genital regions in german shepherds
Perifolliculitis
Inflammation around hair follicle
Luminal folliculitis
Inflammation of lumen of hair follicle
Mural folliculitis
Inflammation within the wall of the outer root sheath
urunculosis
Follicle rupture with inflammation
Folliculitis Gross Appearance
Small papules at inflamed follicles, alopecia
Causes of folliculitis
S. pseudintermedius, Dermatophyte, Demodex
Superficial Pyoderma
Bacterial infection in upper layers of skin and follicle, common in dogs, usually secondary to another condition, S. pseudintermedius, papules, pustules, and epidermal collarettes
Intertrigo
Dermatitis in areas of skin folding due to surface bacteria overgrowth
Deep Pyoderma
Infection of deep dermis and subcutis in german shepherds due to S. pseudintermedius; erythema, ulcers, crusts, bullae, and draining tracts
Post-Grooming Furunculosis
Pseudomonas aerginosa causes acute deep pyoderma after contaminated grooming products or water
Dermatophytosis
Ringworm, young animals and persian and himalayans predisposed, arthrospores in hair follicle cause circular patches of scaling, alopecia, and folliculitis
Dermatophytosis Diagnosis
Hair pluck shows abnormal hair, toothbrush technique, culture on dermatophyte test medium, PCR
Demodectic Mange
Demodex lives in deep hair follicles and causes alopecia, crusting, scaling, and pruritus due to immunosuppression
Feline Herpesvirus Dermatitis
Felid herpesvirus-1 causes erosions, ulcers, and crusts on face, nasal planum, and limbs with rhinitis and conjunctivitis
Feline Herpesvirus Dermatitis Histology
Epithelial necrosis, intranuclear viral inclusion bodies, homogenous lost nuclei
Contagious Ecthyma
Orf, sheep and goat parapoxvirus, vesicles, pustules, ulcers, and crusts on lips, muzzle, face, and oral cavity, usually regresses on its own
Irritant Contact Dermatitis
Inflammatory reaction due to contact with an irritating agent, not allergic, edema, erythema, and papules progress to scales and lichenification
Thermal Burn
Various causes, clinical signs vary based on depth
Type 1 Photosensitization Dermatitis
Primary, due to ingestion of exogenous agents
Type 2 Photosensitization Dermatitis
Endogenous, congenital erythropoietic porphyria, disturbance in porphyrin pigment metabolism
Type 3 Photosensitization Dermatitis
Hepatogenous, plant toxins and mycotoxins
Hepatogenous Photosensitization
Impaired capacity of liver to excrete porphyrins leads to increase in blood levels and dermatitis in sun exposed areas
Nodular/Diffuse Dermatitis
Infectious or non infectious, neutrophilic infiltrates if bacterial, eosinophilic infiltrates if parasitic, histiocytic infiltrates if chronic granulomatous
Nodular Dermatitis Diagnostics
Sterile tissue culture
Canine Leproid Granuloma
Mycobacteria causes firm, nonpainful nodules in short coated breeds, acid fast positive bacteria
Deep Fungal Infection
Cutaneous lesions secondary to systemic infection due to ingestion or inhalation of contaminated soil
Pythiosis
Aquatic dimorphic water mold causes GI disease in dogs and ulcerative lesions with fistulous tracts in horses called kunkers
Leishmaniasis
Intracellular protozoa spread by sandfly bites causes alopecia, ulcers, nodules, and exfoliative dermatitis
Onchiogryphossi
Hypertrophy and increased curvature of the claws
Habronemiasis
Summer sores, nematode transmitted by flies causes granulomatous and eosinophilic dermatitis in horses
Sterile Granulomatous Dermatitis and Lymphadenitis
Facial swelling, papules, and pustules in periocular skin, muzzle, and pinnae of young dogs in response to immunosuppressive drugs, also causes lymphadenomegaly
Eosinophilic Granuloma Complex
Cat allergy manifests as eosinophilic plaque, indolent ulcer, and eosinophilic granuloma
Panniculitis
Inflammation of the subcutis, rule out infectious disease, idiopathic more common in dogs: sterile nodular panniculitis
Panniculitis Diagnostics
Sterile tissue culture
Sterile Nodular Panniculitis
Idiopathic pyogranulomatous dermatitis and panniculitis as ulcerated nodules with draining tracts in dachshund trunks
Atrophic Dermatoses
Noninflammatory alopecia, follicular atrophy, sebaceous atrophy, and epidermal and dermal atrophy due to endocrine dermatopathy, ischemia, and feline acquired skin fragility
Endocrine Dermatoses
Bilateral symmetrical alopecia, hyperpigmentation, epidermal thinning, rough, dry, and dull coat with minimal inflammation
Conditions of Endocrine Dermatoses
Hypothyroidism, Hyperadrenocorticism, Hyperestrogenism, Hyposomatotropism, Hypersomatotropism, Alopecia X
Hypothyroidism
Primary thyroid dysfunction causing bilaterally symmetrical alopecia, thickened and droopy facial skin, and rat tail
Hyperadrenocorticism
Pituitary dependent, Adrenal dependent, or Iatrogenic causes bilateral symmetrical alopecia of trunk, pendulous abdomen, hyperpigmentation, visible veins, comedones, and calcinosis cutis
Alopecia X
Bilateral symmetrical alopecia on trunk, thighs, neck, perineum, and tail in plush coated breeds
Hyperestrogenism
Bilaterally symmetrical alopecia and hyperpigmentation with gynecomastia
Cutaneous vasculitis
Inflammation targeting the walls of venules or arterioles appears as edema, erythematous macules, petechiae, and ecchymoses and ulceration of distal extremities
Diamond Skin Disease
Swine erysipelas causes septicemia, bacterial embolization to kin, vasculitis, thrombosis, ischemia, and infarction showing multifocal skin lesions
Mass Diagnosis
FNA for cytology; cell adhesion for epithelial cells, no clusters for round cells, spindles for mesenchymal cells
Tumor Like Lesions
Cutaneous tags, follicular cysts, and cutaneous horns
Papilloma of Dogs
Oral papilloma, cutaneous papilloma, pigmented viral plaque, squamous cell carcinoma
Papillomavirus in Cattle
BPV 1-3 in young cattle causes cauliflower masses on head, neck, shoulders, teats, and penis
Squamous Cell Carcinoma
Common malignant neoplasm of cats due to UV light or papillomavirus on lightly pigmented skin
Equine Sarcoid
Most common skin neoplasm of equids caused by BPV, locally aggressive but non metastatic originating from fibroblasts
Injection site Sarcoma
Locally aggressive fibrosarcoma due to vaccine, trauma, and foreign material
Hemangioma
Red pigmented nodule, may be hemangiosarcoma
Round Cell Neoplasias
Lymphoma, transmissible venereal tumor, mast cell tumor, plasma cell tumor, or histiocytoma
Histiocytoma
Neoplasia of langerhans cells causes dome shaped lesion in young dogs that undergoes spontaneous regression
Mast Cell Tumor
Most common skin tumor in dogs, alopecic, erythematous, and edematous on trunk, extremities, and head
Canine Cutaneous Epitheliotropic Lymphoma
Generalized scaling, ulcers, and nodules at mucocutaneous junctions due to T cells infiltrating