Skin pathology Flashcards
What part of the skin is the epidermis?
The thin outer portion of the skin, important for the protective function of the skin
What part of the skin is the dermis?
The thicker inner portion, the connective tissue layer- important for sensation, protection and thermoregulation
What part of the skin is the hypodermis?
Part of the skin underneath the dermis and merged with it
What kind of tissue do you find in the hypodermis?
Mainly adipose tissue and sweat glands
What are the 5 layers of the epidermis?
- Stratum basale
- Stratum spinosum
- Startum granulosum
- Startum lucidum
- Stratum corneum
What are the 3 ways cells can adhere to each other in the skin?
- Using hemidesmosones
- Using desmosones
- The basement membrane mediates attachment of the epidermis to the underlying dermis
What is a pilosebaceous unit?
Collective name for the hair follicle, hair shaft and sebaceous gland
What is the name for increased thickness of the stratum spinosum?
Acanthosis
What is lichenification?
Rough thickened epiderms with acentuation of skin creases caused by marked acanthosis
What can cause Lichenification?
Persistent rubbing, scratching or irritation (chronic dermatitis)
What is hyperkeratosis?
Increased thickness of the stratum corneum, due to an abnormal amount of keratin- this is usually associated with epidermal hyperplasia
What is orthokeratotic hyperkeratosis?
When the preserved keratinocytes mature
What is parakeratotic hyperkeratosis?
Nuclei are retained as a sign of delayed keratinocyte maturation
What is the definition of a callus?
- thick, firm hyperkeratotic hairless plaque with increased skin folds
What is the cause of a callus?
trauma over a bony prominence such as an elbow, sternum or side of a digit
What is the similarity and difference between a vesicle and bullae
- they are both ‘blisters’, localised collections of fluid within or beneath the epidermis, elevated fluid-filled lesions differented by size
- Vesicles are less than one cm in diameter, Bulla are more than 1cm in diameter
What causes vesicles/ bullae?
Burns, Viral infections, immune-mediated diseases
What is the definition of a pustule?
- Elevated, pus-filled vesicle usually caused by bacterial infections
What is the definition of an erosion?
Partial-thickness loss of epidermis that results in a shallow, moist depression
the basement membrane remains intact
What causes an erosion?
it is secondary to a vesicle or pustule rupture/ surface trauma
What is the definition of a dried exudate?
fluid, blood, pustular debris or scales left behind on the skin surface
What causes crust?
Often the end result of loss of integrity of the epidermis
What is the definition of an ulcer?
Full-thickness loss of epidermis and the basement membrane
What is the defnition of a scar?
thin to thick fibrous tissue that replaces normal skin following injury or laceration to the dermis
What is epidermal hyperplasia?
Increased numbers of keratinocytes in the epidermis as a response to a variety of stimuli
What is the definition of a blister?
Localised collection of fluid within or beneath the epidermis
What is the definnition of crust?
- Dried exudate
- Often the end results ends in the loss of the integrity of the epidermis
Why would an erosion not bleed?
There are no vessels in the epidermis
What is the definition of an ulcer?
Full-Thickness, loss of epidermis and the basement membrane, and at least a portion of the dermis with depression of exposed tissue- may extend into the deeper tissue
What may cause an ulcer?
ischemic lesions resulting from vasculitis, indolent ulcer, feline herpesvirus, toxicity, self-trauma
What is the definition of a scar?
Thin to thick fibrous tissue that replaces normal skin following injury or laceration to the dermis, hair regrowth may not occur
What is the definition of atrophy?
Decrease in the size of a tissue due to a decreased number of cells
What is dermal atrophy?
Thinning of dermal collagen fibres and decreased dermal thickness
May be associated be alopecia
What causes atrophy?
malnutrition and endocrinopathies
What is the definition of urticaria?
- Smooth, Circumscribed, slightly elevated area of skin, caused by dermal oedema,
What is angioderma?
Vascular reaction involving the deep dermis or subcut, consisting of oedema that manifests as giant wheals and are caused by dilation
What is neoplasia?
abnormal mass of tissue, characterised by excessive and uncoordinated growth and persists in the same excessive manor after cessation of the stimuli which evoked a change
What is albinism?
Inherited disorder that presents with an absence of melanin
What is melanosis?
Excessive production of melanin in the skin
usually secondary to skin damage
