Inflammatory Dermatoses Flashcards
(37 cards)
what kind of cells are found in the stratum corneum?
dead keratinocytes which have lost their nuclei
what kind of cells are found in the stratum granulosum?
cells with keratin granules
much flatter
what kind of cells are found in the stratum spinosum?
- living keratinocytes
- dendritic cells (Langerhan cells)
what kind of cells are found in the stratum basale?
- melanocyte
- dividing keratinocyte (stem cell)
- tactile cell with sensory nerve ending (Merkel cells)
where are the youngest and oldest cells found in the epidermis?
the youngest cells are near the basement membrane where they freshly differentiate
the older cells are closest to the stratum corneum
what are the stages of differentiation of basal cells into keratinocytes?
basal cell
- to prickle/spinous cell (in the spinosum layer)
- to granular cell (in the granulosum layer)
- to keratin producing cell
what are the two layers of the dermis layer?
papillary dermis
reticular dermis
what function does the stratum corneum have and how is this achieved?
barrier function:
corneocytes (differentiated keratinocytes) have a glue around them made of lipids (filaggrin)
what protein is required for the glue around the corneocytes?
what is the result of a defect in this protein (gene) ?
filaggrin
a defect in the protein’s gene predisposes you to eczema
what are the 4 main types of eczema/dermatitis?
- atopic
- seborrhoeic
- discoid
- allergic contact
ASDA
what is the associated tendency with atopic diseases?
the tendency to develop hypersensitivity – includes eczema, hay fever & asthma:
from early life. Many grow out of it
what is the cause of atopic dermatitis?
defective barrier of skin e.g. filagrin epidermal protein gene mutation
what is a sign of filagrin mutation?
palmar hyperlinearity
the lines of the palm are more prominent
what is the consequence of a defective skin barrier due to the mutation in filagrin?
Defective barrier then allows entry of irritants, allergens and pathogens which then cause inflammation.
what is the consequence of chronic scratching and rubbing of atopic dermatitis?
lichenification where the skin becomes thick and leathery
how is severe eczema described?
erythroderma
describe intense and usually widespread reddening of the skin due to inflammatory skin disease.
what are some microbial infections that lead to severe eczema?
staphylococcus, streptococcus and herpes simplex
susceptible to these infection due to eczema
what is seborrhoeic eczema?
Associated with an overgrowth of malassezia (species of yeast on the skin that causes inflammation) with eczema
who does seborrhoeic eczema affect?
Common skin condition affecting babies and adults but is NOT itchy.
distinctive distribution involving
– nasolabial folds, eyebrows, scalp, central chest, axilla and groin.
in what sort of skin is discoid eczema common?
small discrete discs common in overwashed skin due to lack of skin oils
what are the types of psoriasis?
o Chronic plaque.
o Guttate.
o Palmoplantar pustulosis.
o Generalised pustular psoriasis
what is the cause of psoriasis?
many genes are implicated including PSOR1 alongside Environmental causes i.e. triggers like
- alcohol, stress, smoking, drugs (antimalarials, beta blockers) infection (strep)
in infection, tonsillectomy can improve psoriasis
what is the mechanism resulting in psoriasis?
- T-lymphocytes move out of blood vessels into the dermis
- initiate release of cytokines (e.g. TNFa)
- the epidermis thickens in response (produces more keratinocytes)
- Neutrophils infiltrate the epidermis and lymphocytes infiltrate the dermis.
what are the histological features of psoriasis?
proliferation effects:
- hyperkeratosis: thickening due to overproliferation
- parakeratosis: top layer of keratinocytes have not lost their nuclei
- acanthosis: thickening
- inflammation
- dilated blood vessels
