Itchy, bald, and lumpy Flashcards
Innate immunity
The first line of defense. The cells of the innate system recognize and respond to pathogens in a generic way, but unlike the adaptive immune system (which is found only in vertebrates), it does not confer long- lasting or protective immunity to the host. They include both humoral immunity and cell-mediated immunity components.
Humoral immunity
Aspect of immunity mediated by macromolecules (as opposed to cell-mediated immunity) found in extracellular fluids such as secreted antibodies, complement proteins, and certain antimicrobial peptides. (named after the substances found in humours or body fluids)
Cell mediated immunity
Immune response that does not involve antibodies, but involves phagocytes, antigen specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.
Adaptive Immune System
Also comprises of a humeral and cell-mediated components (like the innate immune system). A subsystem of the overall immune system that is composed of highly specialized, systemic cells and processes that eliminate or prevent pathogen growth. It creates immunological memory after an initial response to a specific pathogen, leads to an enhanced response to subsequent encounters with that pathogen. This is the basis of vaccination.
Keratinised epidermal cells (stratum corneum) significance?
Provides protection depending on thickness- it is thickest where frictional forces are greater
What is the function of melanin and hair with protection?
Radiation protection (from UV light)
What has antimicrobial action at the surface of integument?
Stratum corneum (physical barrier) and sebum (some chemical antimicrobial activity)
What purpose does the stratum corneum serve?
Physical barrier to fluid to microbes, also controls fluid permeability (along with hair)
What characteristics of integument provide thermoregulation?
skin surface area (ratio to body mass), cutaneous blood flow (arteriovenous anastomoses), hair (insulation), cutaneous and subcutaneous fat (insulation), and sweat glands (number and efficiency)
What is the basic structure of skin?
2 main layers + hair & glands
What are the two main layers?
*Epidermis- ectoderm derived stratified squamous epithelium (keratinized) *Dermis- mesoderm derived connective tissue
What attaches the epidermis and dermis to underlying structures (deep fascia and muscle, etc.)?
Hypodermis (subcutis/ superficial fascia). Lowermost layer of the integumentary system in vertebrates. The types of cells found in the hypodermis are fibroblasts, adipose cells, and macrophages.
What are the two appendages of skin (skin derivatives)?
- Keratinised appendages e.g. scales, hair, horns, and hoofs 2. Glands- sebaceous glands, tubular glands, special glands i.e. scent and regional glands
a. dermis
b. epidermis
c. hair follicle
d. glands
a. str corneum
b. str ganulosum
c. str spinosum
d. str basale
Single layer of cuboidal to columnar cells
Stratum basale
Polygonal cells become squamous toward the surface, desmosome junctions
Stratum spinosum
str spinosum
str basale
What are the active cells of the epidermis?
Tonofilaments + non-membrane bound keratohyalin granules _ membrane bound lamellar granules
What are the inactive cells of the epidermis?
Keratohyalin granules are concentrated in the str. granulosum
Inactive
Active
Proliferative
Do albino animals have melanocytes?
Yes. They just don’t have enzymes to make melanin but they do have the melanocytes
Melanin granules
Melanocytes
What are Langerhans cells?
*Dendritic cells (antigen presenting cells) of the skin
*Similar in morphology and function to macrophages
*Most prominent in the stratum spinosum
What are Merkel cells?
Sensory, associated with tactile stimulation and nerve cells
Tonofilament (bundles called tonofibrils)
A cytoplasmic protein structure in epithelial tissues that converge at desmosomes and hemidesmosomes anchoring them to the cytoskeleton. They are made of keratin tonofilaments.
Desmosome
A cell structure specialized for cell-to cell adhesion. A type of junctional complex. They help to resist shearing forces and are found in simple and stratified squamous epithelium. Also found in muscle tisse where they bind muscle cells together.
Dermal papillae
Important so you can see pathological changes
(epidermis is the top and the dermis is the bottom)
Epidermal pegs
(epidermis is the top and the dermis is the bottom)
What makes up the dermis?
Cells, intercellular substances, appendages, vascular plexuses
What is the importance of the vascular plexuses found in the dermis?
Allows the shunting of blood through different levels of the dermis in response to changes in the environmental temperature, fluctuations in circulating blood volume
What is an example of an antigen presenting cell relevant to the skin?
Langerhans cells
What inhibits the activation of ILC2s?
In homeostatic conditions, the expression of adhesion molecule E-cadherin on normal human keratinocytes inhibits the activation of ILC2s
What are ILCs? Examples relevant to the skin.
Group of innate immune cells that belong to the lymphoid lineage but do not respond in an antigen-specific manner, as they lack B or T cell receptors. Differing functions.
Innate Lymphoid Cells. ILC1, ILC2, ILC3
Different cell surface markers producing cytokines.
Cytokines
Small proteins that are important in cell signaling.
What are keratinised appendages of the skin (skin derivatives)?
Scales, hair, horns, claws, and hoofs
What glands are related to the dermis and epidermis?
Sebaceous glands, tubular glands, and special glands (scent and regional glands)
Carpal pad
Metacarpal pad
Digital pads
str spinosum
str lucidum
What are structures unique to horses skin?
Chestnut and ergot
What are chestnuts and ergots?
Epidermal thickenings found in horses. Ergots can be found on both front and back legs. Ergots are small growthso n the back of the fetlock.
- tubular horn (dermal papillae produce the tubular horn)
- intertubular horn (just the part in between tubular horns)
* these are just structures
What are horns comprised of?
Keratinized epidermis–> papillated dermis–> thin hypodermis–> periosteum of the bone
What are epikeras?
At the root of the horn, similar to the epidermis of teh periople of the hoof
What are claws made of?
Shells of hard keratin produced by the epidermis covering the ungal process of the third phalanx
- Claw fold
- Dermis
- Digital pad
- Distal phalanx
- Limiting furrow
- middle phalanx
- sole
- wall
Merocrine
Small secretory product of granule + cell membrane via exocytosis
Apocrine
Large granule + a rim of cytoplasm + cell membrane
Holocrine
Entire cells are released as the secretory product; sebaceous glands of the skin are typical holocrine glands (sebum)
Cytocrine
Secretory material is transferred from one cell to the cytoplasm of another cell i.e. melanin from melanocytes to keratinoctyes
Apocrine sweat gland
* Discharge an albuminous sweat
* secrete into the hair follicles, but important species differences on distribution
Merocrine sweat gland
* secrete a more watery sweat
* secrete onto certain regions of the skin (e.g. the nasolabial plate of cattle and footpads of dogs)
Functions of hair, wool, and fibre
Protection (physical, radiation, antimicrobial, immunity)
* control of fluid permeability and barrier to chemicals
*sensory activity: cutaneous nerve endings, stout tactile hair (sinus hair) (Merkel cells)
*Nutritional: Vitamin D3
* Social: sexual attraction, territorial marking and individual and species identification
* Indicator of health (direct observation and palpation)- hair loss, rough hairs
What are the three forms of hairs?
- Straight, rather stiff guard hairs “top coat”
- Fine, wavy wool hairs “undercoat”
- Stout tactile hairs- restricted distribution associated with touch receptors
Medulla
A solid column of cuboidal cells to a system of air filled spaces
Cortex
Contain melanin acquired from melanocytes, fibrillar keratin in an amorphous matrix
Cuticle
The outermost single layer of overlapping flat keratinized cells
Medulla
Cortex
Cuticle
Keratin Associated Proteins (KAP)
Consitute the matrix of the keratin composite of wool. Large group of possibly up to 100 different proteins. Intermediate filaments (IFs) constitute macrofibrils.
What is soft keratin?
Keratin that has a high lipid content and low sulfur content
Cortex
Cuticle
Medulla
external root sheath
dermal root sheath
matrix
dermal papilla
Dermal papilla
The region of connective tissue
What does CTS, DP, HS, IRS, and ORS stand for?
Connective tissue sheath (dermal root sheath), dermal papilla, hair shaft, inner root sheath, and outer root sheath
Arrector Pili Muscles
Smooth muscles, attaches to the dermal root sheath of the follicle and the superficial layer of ther dermis, well developed along the back of dogs, cause the hair to bristle when they contract, contract to form dead-air space to provide insulation to help to maintain internal body temp in cold weather
Dermal root sheath composed of collagen and elastic fibres
Secondary follicles (as opposed to primary/ simple)- compound
Have sweat glands, there is no medulla, muscle
Sinus (tactile) hair follicle (e.g. whisker)
- annular sinus
- connective tissue sheath, inner
- connective tissue sheath, outer
- epidermis
- inner root sheath
- outer root sheath
- sebaceous glands
- sinus pad
- trabecula
Trabeculated sinus traversed by what?
Fibroelastic trabeculae containing many nerve endings
Tactile hair example
Whiskers
Anagen
phase of the hair cycle- Growth phase- repetitive cycles of growth
Catagen
Recession phase- apoptosis driven regression
Telogen
Resting phase- relative quienscence
What are hair cycles controlled by?
Daily period of light, ambient temperature (seasonal change), nutrition, hormones (estrogen especially, testosterone, adrenal steroids, thyroid hormone)
What does a microscopic examination of the hair root tell us?
Whether hair has fallen out or been plucked out
Follicular cast
An accumulation of keratin and follicular material to the hair shaft
Staple
The fiber of cotton or wool considered with regard to its length and degree of fineness
Crimp
A natural wave formation visible in wool. In general, the closer the waves are together, the finer the wool
How is nutrition key to wool growth?
Supply of energy and protein
Factors: pregnancy, hypoxia, environmental stress, hormones (i.e. cortisol), etc.
What are the most important amino acids in hair growth?
Cysteine and methionine
What are the key trace metals in hair growth?
Copper and Zinc
What does a deficiency of copper and zinc do to wool?
Copper deficiency- highly reduced crimp. “steely”
Infundibulum
Most proximal part of the hair follicle relative to the epidermis, extending from the sebaceous duct to the epidermal surface. Includes the hair canal and the distal outer root sheath.
Sebaceous gland
Acinar gland composed of lipid filled sebocytes, localized close to the insertion of the arrector pili muscle. Secretes sebum to the epidermal surface via a holocrine mechanism. Sebum helps making hair and skin waterproof. together with the hair follicle and the arrector pili muscle it forms the pilosebaceous unit.
epidermis
dermis
subcutis
f- hair follicles
a- arrector pili muscles
s- sebaceous glands
t- tubular glands
epidermis
a keratin
b basal cells
c epithelial cells organized in columns
a external root sheath
b dermal sheath
internal root sheath
dermal papilla
germinal hair matrix
a. sebaceous glands
b. hair follicle lumen
c. duct
d. external root sheath of hair follicle
tubular sweat glands
arrector pili muscles
tubular glands
Stratum corneum
stratum granulosum
stratum spinosum
stratum basale
Hyperkeratosis
* stratum corneum
* excess keratin formation
* clinical signs associated with seborrhea
* scaling, crusting, greasiness
Sebhorrhea
Excessive scaling, crusting and greasiness
Hyperkeratosis. Seborrhea
Primary Seborrhea
Excessive scaling (dandruff). Oily and crusty skin as well.
Sarcoptic mange (scabies)
Itchy. Transmissible from dogs to dogs, dogs to humans, humans to humans. Crusty skin and diffuse hyperkeratosis. Lives in the epidermal layer (stratum corneum).
Dog scabies.
Scabies (sarcoptic mange)
Ancanthosis (epidermal hyperplasia)
Not specific to any disease. Always present in chronic skin disease of all causes. The first reaction of skin to nearly any injury.
Hyperkeratosis
Acanthosis (epidermal hyperplasia)
How many layers of epithelial cells should you have in normal skin?
Thinner skin- 1-2 layers
Skin of higher pressure i.e. elbows- 4-5 layers
Therefore greather than 5 layers of epithelial cells= acanthosis
Lichenification
Thickened and leathery skin
Lichenification (severe and chronic form of acanthosis)
Callus
Callus
Localized, hyperplastic skin reaction to trauma caused by pressure or friction.
Actinic keratosis
Actinic keratosis
Epidermal hyperplasia from exposure to UV radiation. Precancerous lesion. Can develop into squamous cell carcinoma. Sparsely haired, non pigmented areas of the skin are most commonly affected
Actinic keratosis.
Erythema
Redness of the skin due to congestion of capillaries.
Erythema. Allergic dermatitis (miliary dermatitis)
Comedone (comedo)
A comedo is a clogged hair follicle (pore) in the skin.[1] Keratin (skin debris) combines with oil to block the follicle.[2] A comedo can be open (blackhead) or closed by skin (whitehead), and occur with or without acne.[2]
Erosion vs. Ulceration
Complete loss of the epidermis in one area. Erosion is reddening of the skin but usually you don’t have bleeding (epidermis doesn’t have vessels). Ulceration, you will see a lot of bleeding because the dermal vessels are exposed.
Name the degrees
Describe necrosis of the skin from a burn.
Cannot see cellular detail.
Spongiosis
Intercellular oedema. Accumulation of fluid between cells. You can see the spines of the keratonocytes (desomosomes). With fluid, those connections look like spikes. Cannot see grossly.
Spongiosis (intercellular oedema)
Malassezia infection
Normal inhabitant of the skin but with a immunocompromise or minor trauma or excessive moisture, allergy, hypersensitivity reactions- malassezia proliferates and causes dermatitis.
Malassezia infection. What you can see is achantosis or lichenification. (Increased folding)
Malassezia infection
Scabies vs.
Malassezia infection
scabies is normally on back. Malassezia infection on stomach
Spongiosis vs. Ballooning degeneration
Spongiosis: between cells
Ballooning degeneration: intracellular oedema (pox virus)
Ballooning degeneration
Acantholysis
typical reaction to immune mediate diseases. Separation of keratonocytes. Loss of cohesiveness of epithelial cells in the epidermis. Not common.
Acantholysis
Vesicles. Fluid-filled blisters in the superficial epidermis.
3 ways vesicles (aka bullas) form
Spongiosis, ballooning degeneration, acantholysis
Name four vesicular diseases
FMD, Vesicular stomatitis, vesicular exanthema, swine vesicular disease
How does a vesicle form?
Cytopathic viral effect–> ballooning degeneration of epithelial cells–> rupture of epithelial cells and loss of cohesiveness–> vesicle
Vesicular diseases
Contagious ecthyma
Crusty scabs ont he lips (dermatitis and cheilitis). Histologically there is ballooning degeneration and inclusion bodies in the keratinocytes. The infection is transmissible to humans (by direct contact)
Contagious ecthyma
What is this? And what is in it?
Pustule
Inflammatory cells (as opposed to a vessicle with fluid)
Pemphigus foliaceus
Autoimmune disease. Antibodies destroying desmosomes. Eventually lesion (pustule) will burst and exudate will be exposed on the surface of the skin, dry out, formation of crusts.
Pemphigus foliaceus
Pemphigus foliaceus.
Crust
Crust: Evolution of lesions?
Photosensitization
Dermatophylosis
Hair is matted by a crust composed of dried exudate, stratum corneum and bacteria. Opportunistic infection. Loss of integrity of skin barrier, bacterium can become a pathogen.
Dermatophylosis
Dermatophilosis
Greasy pig disease
Exudative epidermitis. Fatal disease of piglets (only in the first week of life- neonatal piglets). Common. Immune system is not developed, which is the reason it is fatal. Caused by stapphylococus. Skin is greasy and moist with malodorous exudate. Epidermal hyperplasia (achanthosis) and suppurative exudate within the lumen of the hair follicle and on the surface of the epidermis. Lesion starts as a pustular disease (intraepidermal collection of neutrophils) which extends to the follicles; the pustules rupture, the exudate dries and the crusts form.
Greasy Pig Disease
What are the structures of adnexa?
hair follicles, sebaceous glands, and sweat glands
What are the 3 responses of the adnexa to injury?
Atrophy, dysplasia, inflammation
(Adnexa- hair follicles, sebacesous glands, and sweat glands)
Endocrine dermatoses.
Cushing’s Disease. Excess activity of adrenal glands. Causes atrophy of the skin (epidermis, dermis, and most importantly hair follicles). Microscopically- hair follicles look really small.
Cushing’s disease. Thin skin. missing hair. If skin looks transulcent and thin- it can easily rupture.
Hypothyroidism.
Folliculitis vs. furunculosis
Location of the inflammatory infiltrate.
Folliculitis- confined within follicle lumen (where the hair shaft is supposed to be)
Furunculosis- inflammation extends and ruptures the follicular wall and extends into the dermis
Furunculosis. A circular area of erythema, scaling and crusting, caused by furuncolosis (follicular wall rupture)
Demodicosis
3 diseases of folliculitis and furunculosis
Staphylococus (bacterial cause)
Ringworm
Demodicosis
Demodicosis
Parasite which causes inflammatory reaction. Rupture of the hair shaft. Therefore you will get folliculitis and furunculosis
Demodicosis
Dermatophytosis
Ringworm. Fungi. 3 main fungi that cause ringworm- 2 are
Microsporum & Trichophyton. Multifocal erythematous plaques, patches of alopecia and mild surface crusting.
Ringworm (Dermatophytes)
Why does ringworm cause hair loss?
Hair loss is caused by breakage of hair shaft due to inflammation
3 responses of the dermis to injury
Dermal atrophy, fibrosis, inflammation.
(Fairly unreactive composed of collagen- fairly unreactive- support structure. Dermis- fibroblasts- sparse and not doing much. So reactions are quite bland usually. Fibrosis and atrophy are not common)
Fibrosis (scars, granulation tissue)
Dermatitis
Dermal inflammation. Macrophages (granulomatous)- Mycobacterium spp.; Neutrophils (suppurative)- bacteria; Eosinophils: allergy (hypersensitivity), parasites, EGC in cats
Flea bite hypersensitivity
Flea bite allergy (to the saliva of fleas). Perivascular interstitial dermatitis with eosinophils and later mononuclear cells, spongiosis and microabscesses.
Mycobacterial granuloma- feline leprosy
Feline Leprosy
Caused by opportunistic bacteria. Loss of integrity of the skin barrier. Traumatic injury in cats- microbacteria enters the breach and causes granulomas.
Feline Leprosy
Feline eosinophilic granuloma
Acute or Chronic?
- Acute (red)
- Acute (oedema or swelling)
- Chronic (thickenings or scaring)
A Epithelial
B Mesenchymal
C Round
Benign cutaneous hisiocytoma. Round cell tumour. Typical tumour of young dogs. Usually occurs in dogs up to 2 years old. “Button tumour”. Spontaneously regressing.
Benign cutaneous histiocytoma
Mast Cell Tumour. The top picture does look like a button tumour- one way to differentiate is the age of the dog. If the dog is older, it is unlikely to be a button tumour.
Mast cell tumour. Neoplastic cells are round and contain abundant granules in the cytoplasm.
Cutaneous Lymphoma. Multiple lumps in the subcutis.
Cutaneous epitheliotropic lymphoma (mycosis fungoides-name comes from the fact that it used to be diagnosed as a fungal infection). Multifocal to coalescing erythematous plaques and papules. Early lesions resemble inflammatory skin disease and are often misdiagnosed.
Melanocytic tumours. Raised pigmented brown to black hairless mass.
Melanocytosis
Grades of Mast Cell Tumours and their prognosis and treatment
Grade I- removal, likely will not return
Grade II- intermediate- could go either way upon removal
Grade III- will almost definitely come back upon removal
Malignant melanomas. Progressed from melanocytoma (possibly benign at first)
Transmissible venereal tumor. Round cell tumour.
Lipoma.
Haemangioma. Well defined mass of proliferative, blood-filled, vascular channels in the dermis.
Haemangiosarcoma
Fibrosarcoma- soft tissue sarcoma. Extremely invasive, extremely malignant. 4-5 surgeries and they continue to come back.
Equine sarcoid. Tumour that only occurs in horses. Many different presentations. Verrucous type (proliferating containing keratin and epithelium) and proud flesh type are the two most common forms. Caused by a viral infection with bovine papilloma virus 1 or 2 (NOT EQUINE) affects fibroblasts- undergo transformation and give rise to sarcoids.
Papilloma (wart). Epithelial cells can give rise to benign tumours called papillomas. Viral. Proliferation of epithelium that projects. In dogs they regress spontaneously in most cases. Immune system reacts towards neoplastic cells.
Squamous cell carcinoma. Common in cats. Tumour arises from squamous cells in the epidermis (arises from the squamous layer of the epidermis). Highly malignant. Associated with UV light exposure. Concurrent lesions in the same animal actinakeratosis- can progress to squamous carcinoma.
Squamous cell carcinoma in a dog.
Squamous Cell Carcinoma in a cow.
Sebaceous gland adenoma. Typically protrudes from the surface is hairless and greasy. Very common especially in older dogs.
Alopecia
Loss of hair- multifocal, patchy, etc.
Hyperpigmented
Darker skin. Hyperthyroidism, adrenal X syndromes
Macules
Circumscribed, non-palpable or well defined
Papule
Elevated lesion (vs. macule)
Rash
Erythematous macules, papules, and pustules
Nodule
Sub dermal mass not associated with an organ. Not crusting, not erythematous
Scale
Partially sloughed squames, attached to skin or hair (dandruf). Can be a vitamin deficiency, for example
Epidermal collarette
circular ring of scale (sometimes seen with ringworm)
Comedone
dilated hair follicle filled with sebaceous material but no hair shaft
Drainging Tract
Opening between sub-cutis and epidermis
Fissure
Splite in the epidermis (nose and footpads) (e.g. trauma or nutritional deficiencies)
Most likely issue regarding speed of change?
Quick
Cyclical
Slowly
Quick= infection, autoimmune, parasitic
Cyclical= allergic
Slowly= allergic, endocrine
Pruritis grades define
Grade 0- dog does not itch….
Grade 5- itches continuously, needs to be restrained to stop, doesn’t sleep
Skin Scraping
Used to detect mites, need to do 5-10 skin scrapings per animal, sarcoptes spp. are superficial, deeper mites- Demodex spp (seen in an immunosuppressed animal) will need to obtain blood on the scrape in order to get diagnostic samples
Combing of the hair coat
Useful to show owner that animal has fleas. Flea dirt will dissolve when moistened with water.
What are you trying to determine with ear smear?
Yeast or bacteria
Wood’s lamp used for?
Looking for a fungal infection. Fungal culture is required to confirm diagnosis.
What is cytology used for in dermatology?
Fine needle aspirate
Intra dermal skin testing
Variety of allergens injected, 1+, 2+, or 3+ as the size of the wheel. Determine which allergens cause the greatest reaction. You can develop desensitization programs.
Atopy
Predisposition toward developing certain allergic hypersensitivity reactions.
