Skin pathology Flashcards
What are the layers of the epidermis?
- statum corneum
- stratum spinocum
- stratum basale
- basement membrane below these
What does the dermis contain?
- vessels
- collagen
- nerves
What is adnexa?
- hair follicles
- sweat glands
- sebaceous glands
What are examples of epidermal responses to injury?
- hyperkeratosis
- epidermal hyperplasia
- malassezia
What is hyperkeratosis?
- =increased thickness of the stratum corneum
- very common feature of longstanding surface trauma
What are the clinical signs of hyperkeratosis?
- dry flaky skin
- scales
What are the diseases/conditions characterised by hyperkeratosis?
- any chronic surface injury
- seborrhea
- zinc deficiency
- endocrinopathies
What is this animal presenting?
- severe hyperkeratosis
What condition is this?
- hyperkeratosis due to zinc deficiency
- very thick layer (epidermis)
What disease does this calf have?
- congenital ichtyosis (fish skin disease)
- hairless skin
- thickened and scaly
What is epidermal hyperplasia?
- increased numbers (therefore layers) of keratinocytes in the epidermis
What is Acanthosis?
- specific term that refers to increase thickness of the stratum granulosm
What is the earliest reaction to skin injury?
- epidermal hyperplasia
What condition is this showing? What are the signs?
- epidermal hyperplasia
- see mild hyperkeratosis
What condition does this dog have?
- long standing duration epidermal hyperplasia = alopecia
What condition is shown here?
- malassezia
- keratinocytes
In what circumstances can epidermal hyperplasia occur?
- occurs in hypersensitivity disorders (allergy)
- e.g. flea bite reactions
- recruits eosinophils and mast cells
What skin condition is shown here?
- lichenification (severe epidermal hyperplasia)
- thickened and leathery skin = exaggeration of the normal skin markings resulting from longstanding surface trauma or friction
What is this and where does it normally occur?
- callus =thickened often pigmented and hyperkeratotic plaque
- hyperkeratosis and hyperplasia at the same time
- tends to occur at pressure points such as elbow/ chronic licking/ rubbing
What are vesicles and bullae and what are the causes?
- = fluid filled cavities within or beneath the epidermis (blister)
- causes
- frictional trauma
- autoimmune diseases (targeting IC juntions between keratinocytes)
- burns
- viral diseases (FMD)
What is the difference between vesicles and bullae?
- vesicle = <1cm
- bullae = >1cm
What is shown here?
- vesicle and bullae
What is shown by the star?
- sub-epidermal vesicle due to thermal burn
What are examples of vesicular diseases? and how do vesicles form?
- FMD
- vesicular stomatitis
- vesicular exanthema
- swine vesicular disease
What is a pustule and what are the causes?
- vesicle containing pus (=degenerate neutrophils, inflammatory cells)
- causes:
- autoimmune diseases (e.g. pemphigus)
- bacterial infections (e.g. staphylococcal infection = superficial pyoderma)
What is this?
- pustule
- contained within epidermis