Psthology of Rashes Flashcards
what is the endocrine function of the skin?
UV stimulation of vitamin D
what happens when cells become corneocytes?
nuclei are lost
cells are then shed from the upper surface of skin
what is contained within the granular layer?
keratohyalin granules
what do melanocytes do and how?
synthesise melanin pigment and transfer it to keratinocytes via dendritic processes
found in basal layer
what do Langerhans cells do?
found in upper and mid-dermis and act as sentinels monitoring environment for antigens and initiate inflammation through dendritic function
what are the 2 parts of the dermis?
papillary dermis = thin superficial layer
reticular dermis = thicker deeper layer containing type 1 collagen and skin appendages
what is the epidermal basement membrane made of?
laminin and collagen 4
what holds the dermis onto the epidermis?
hemi-desmosomes at the dermo-epidermal junction
what is parakeratosis?
persistence of nuclei in cells in the keratin layer - sign that epidermal turnover is too fast - psoriasis
what is acanthosis?
increased thickness of epithelium
what is papillomatosis?
irregular epithelial thickening
growth of dermal papilla upwards into the epidermis
what is spongiosis?
oedema fluid between squamous cells of the epidermis, increasing the prominence of intracellular prickles
hallmark of eczema
what are the 4 main reaction patterns of inflammatory skin disease?
spongiotic-intraepidermal oedema - eczema
psoriasiform - elongation of rete ridges - psoriasis
lichenoid - basal layer damage - lichen planus, lupus
vesiculobullous - blistering - pemphigoid, pemphigus, dermatitis herpatiformis
describe the pathogenesis of psoriasis
increased epidermal turnover leads to epidermal hyperplasia
complement attracts neutrophils to keratin layer
koebner phenomenon
hereditary factors (specific HLA types)
what are some features of psoriasis plaques?
well defined
erythematous as blood vessels run close to the top due to dermal papillae
symmetrical
on extensor surfaces