Loco dermatology Flashcards
Keratin filament type
Intermediate
Soft vs hard keratin
Soft = alpha helices Hard = beta sheets
What links keratinocytes?
Desmosomes
What joints basal keratinocytes to the BM?
Hemidesmosomes
Cells in basal epidermis
Compact cells with dark nuclei
Stem cells that proliferative and migrate upwards
Cells in spinous layer
3-4 cells thick
Spiny cells as many desmosomes
Cells in granular layer
Dark purple cells
Stained due to keratohyaline granules that form substances that form protective barrier of the skin
Cells in cornified layer
Flat cells with no nuclei or organelles
Main cell type of the dermis
Fibroblast
3 layers of dermis
Papillary = below BM with disorganised arrangement of collagen fibres Reticular = thick layer where collagen is more organised Adipose = made of adipose tissue = hypodermis
Parts of the hair follicle
Dermal papilla = fibroblasts controlling hair growth
Bulb = matrix keratinocytes make cells to make hair
Outer root sheath = basal cell layer around the edge
Bulge region = hair follicle stem cells that migrate downwards
Stages of the hair cycle
Anagen = active = hair growing in length Catagen = regressive = hair follicle retracts Telogen = resting = end of cycle
Eccrine sweat gland
Regular sweat glands
Important for thermoregulation
Apocrine sweat gland
Specialised sweat gland found in axilla and pubic regions
Odourless sweat produced that then is digested by bacteria to make it smell
Melanocytes
Dendritic cells of the epidermis
Project to keratinocytes and inject melanin to give pigment
Langerhans cells
APCs of the skin
Mainly in basal and spinous layers of epidermis
Merkel cell
Found in basal layer
Sense fine tough
Mast cell
Found in dermis
Important for allergic responses
Secrete histamine
Phases of wound healing
Inflammation = blood clot and recruitment of immune cells Proliferation = keratinocytes and fibroblasts proliferate to form new skin Maturation = remodelling of skin to improve structure
Risk factors for chronic wounds
Diabetes
Venous disease
Bedridden
Th1 response
Intracellular bacteria or viruses
Th2 response
Allergens, parasites
Th17 response
Extracellular bacteria and fungi
Dust mite allergy
Allergy to Der P1 wound in faecal pellets of dust mites
Hives vs acute angioedema
Hives = epidermis only Angioedema = also dermis and subcutaneous tissues
Where does angioedema occur?
Lower lips
Eyes
Pharyngeal mucosa
Mechanisms of cell death in type 2 hypersensitivities
Complement dependent cytotoxicity
Anti-body dependent cell mediated cytotoxicity
Phagocytosis by macrophage
Receptor blockade
Pemphigus vulgaris
Development of IgG antibodies against desmoglein in desmosomes
Leads to skin blistering = acantholysis
Diagnosis = incubation –> chicken wire appearance
Treatment = steroids, rituximab
Cascade of contact allergic dermatitis
Skin exposed to allergen
Langerhans cells take antigen to lymph node
Activation fo T cells and memory formed
Upon challenge –> activation and immune response
Types of giant cells
Langham’s = peripheral nuclei
Foreign body = random nuclei
Alopecia areata
Antibodies against follicle
Exclamation mark hairs
Hair regrowth is white
Viteligo
Antibodies against melanocytes
Skin loses pigmentation
Staphylococcus vs streptococcal skin infections
Staphylococcal found on 20% of people
Streptococcal rarely found on skin
Staph infections more common
Strep infections more severe
Folliculitis
Infection of hair follicle
Impetigo
Infection of epidermis
By strep or staph
Tx = topical ABx
Cellulitis
Infection of dermis and subcutaneous fat
More commonly due to streptococcus but also due to staphylococcus
Oral ABx required
Staphylococcal scalded skin syndrome
Toxins from bacteria lead to desquamation of the skin
Toxic shock syndrome
Staphylococcal toxins cause severe systemic illness
From keeping tampons in too long
Nectrotising fasciitis
Infection that leads to soft tissue death
Most common cause = MRSA
Treatment = debridement and BSABx
Reasons for deterioration in eczema patients
Herpes simplex
Staphylococcus
Molluscum contagiosum
Viral infection
Leads to small umbilicated lesions
Tinea vesicolour
Pityriasis vesicolour
Yeast overgrowth leads to hypo/hyperpigmentation
Pathogen = Malassezia furfur
Tinea corporis
Fungal infection
Ring shape structures
Scabies
Severe itchy skin
No history of eczema
Skin-skin contact
Pimple like rash
