Week 10 - Dermatology Flashcards
For what 7 reasons is dermatology important?
- Accounts for ~20 % of GP consultations
- 1 of busiest Hospital OP specialties
- Can have significant psychological impact
- Skin changes can be marker of underlying systemic disease
- Huge increase in rates of skin cancer
- Research important as no cure for melanoma
- Need to be aware of cosmetic dermatology
What is the largest organ in the body?
Skin (15% of body weight)
Describe skin shedding?
Every 24hr skin sheds layer dead cells, renewed fully approx 28 days
What is the pH of skin?
Slightly acidic 5.4 due to Lactic & Amino acids
What are the 3 main functions of skin?
- Protection
- Regulation
- Sensation
List the 5 primary barrier functions of skin?
- Mechanical impacts
- Protects & detects pressure
- Detects variations in temperature
- Barrier to micro-organisms
- Barrier to radiation / chemicals
Describe the physiological regulation of the skin?
- Body temperature via sweat, hair & changes in peripheral circulation
- Fluid balance via sweat & insensible loss
- Synthesis of Vitamin D
What are the 4 layers of skin?
- Epidermis
- Basement membrane
- Dermis
- Subcutaneous tissue
What 3 anatomical features does skin have?
- Glands
- Hair follicles
- Capillaries
What are the 4 layers of the skin epidermis?
- Stratum corneum
- Stratum granulosum
- Stratum spinosum
- Stratum basale
What 3 cells does stem cells develop into?
- Ectoderm
- Mesoderm
- Endoderm
Give 4 examples of what ectoderm develops into?
- Skin
- Hair
- Brain
- Nerves
Give 5 examples of what mesoderm develops into?
- Cardiac
- Skeletal
- Renal
- Muscle
- Blood
Give 4 examples of what endoderm develops into?
- Lung
- Gut
- Thyroid
- Pancreas
What is the epidermis early fetal period invaded by?
Melanoblasts, cells of the neural crest origin
When is hair developed on the skin?
3rd month as an epidermal proliferation into dermis
What happens to the cells of the epithelial root sheath?
- Proliferate to form a sebaceous gland bud
- Sweat glands develop as downgrowths of epithelial cords into dermis
Describe langerhans cells (LC)?
Members of the dendritic cells family, residing in the basal layers
Describe how the skin langerhans cells specialise in antigen presentation?
Acquire antigens in peripheral tissues, transport them to regional lymph nodes, present to naive T cells & initiate adaptive immune response
What do activated T cells initiate?
Cytokine release cascade
List the 4 other things that the skin’s immune system is involved in?
- Antimicrobial immunity
- Skin immunosurveillance
- Induction hypersensitivity
- Pathogenesis of chronic inflammatory diseases of the skin
What induces langerhan cell migration & maturation in skin allergy?
Skin irritation by nonallergenic & allergenic compounds
Describe the migration of Langerhan cells?
Epidermis to draining lymph nodes
How long does the initial sensitisation in skin allergy take?
10-14 days from initial exposure to allergen (nickel, dye, rubber etc)
What happens once an individual is sensitised to a chemical?
Allergic contact dermatitis can then develop within hours of repeat exposure exposure
What are the damaging effects of ultraviolet on skin?
- Direct cellular damage & alterations in immunologic function
- Direct effects include photoaging, DNA damage & carcinogenesis
What is mutated by DNA damage & how is this implicated?
- P53 tumour suppressor gene
- Implicated in development of melanoma & non melanoma skin cancers
What work together to protect cells from UV DNA damage?
Keratinocytes & melanocytes
What 5 things does chronic UV exposure in humans eventually lead to?
- Loss of skin elasticity
- Fragility
- Abnormal pigmentation
- Hemorrhage of blood vessels
- Wrinkles & premature ageing
What happens during exposure to sunlight?
Solar UVB photons are absorbed by 7-dehydrocholesterol in the skin & converted to previtamin D(3)
What happens to pre-vitamin D(3)?
Undergoes transformation within the plasma membrane to active vitamin D(3)
What is the skin problem during winter?
Minimal pre-vitamin D(3) production in the skin & few foods naturally contain Vit D
What are the 4 associated increased risks with Vitamin D deficiency?
- Common cancers
- Autoimmune diseases (MS)
- Infectious diseases
- Cardiovascular disease
What can cutaneous receptors be?
Encapsulated nerve endings such as Meissner, Pacini & Ruffini corpuscles or Free nerve endings associated with Merkel cells
Describe Merkel cells?
- Base of the epidermis,
- Respond to sustained gentle & localised pressure, assess shape /edge
Describe Meissner corpuscles?
- Immediately below epidermis & are particularly well represented on the palmar surfaces of the fingers and lips
- They are especially sensitive to light touch
Describe Ruffini’s corpuscles?
- In the dermis
- Receptors sensitive to deep pressure & stretching
Describe Pacinian corpuscles?
- Mechanoreceptors present in the deep dermis, sensitive to deep touch, rapid deformation of skin surface and around joints for position/proprioception
What is a macule?
Flat area in the skin, usually a change in colour (pigmented)
What is a papule?
Something small raised in the skin
What is a pustule?
Raised & full of puss (infection/inflammatory cells)
What is a plaque?
Raised and tends to be big
What is a vesicle?
Tiny blisters
What is a bulla?
Giant blisters
What is Erythematous?
Redness
What is Ulceration?
The epidermis has been removed and you are left with just the deaper levels of skin
What are the 5 etiological stages of acne?
- Accumulation of epithelial cells & keratin
- Androgenic accumulation of shed keratin & sebum
- Blockage of sebaceous gland
- Propionibacterium acnes proliferation & inflammation
- Scarring
List the 7 clinical features of acne?
- Papules
- Pustules
- Erythema
- Comedones
- Nodules
- Cysts
- Scarring
What 3 clinical features are needed to make a diagnosis of acne?
- Papules
- Pustules
- Comedones
What are comedones?
Blackheads/ whiteheads
What are the 4 distributions of acne?
- Face
- Chest
- Back / Shoulders
- Occasionally legs, scalp
What are 3 clinical types of acne?
- Papulopustular
- Nodulocystic
- Comedonal
What are the 4 subtypes of acne?
- Steroid induced
- Acne fulminans
- Acne rosacea
- Acne Inversus (Hidradenitis suppuritiva)
What are the different grades of acne?
Grades 1-7 (the Leeds Acne photographic grading system)
What are the 2 medications to reduce plugging in acne?
- Topical retinoid
2. Topical benzoyl peroxide
What are the 3 medications to reduce bacteria in acne?
- Topical antibiotics (erythromycin, clindamycin)
- Oral antibiotics (tetracyclines, erythromycin)
- Benzoyl peroxide reduced bacterial resistance
What medication can reduce sebum production in acne?
Hormones- anti androgen ie Dianette / OCP
List the 4 side effects of topical agents in acne?
- Irritant
- Burning
- Peeling
- Bleaching
What is the side effect of oral antibiotics for acne?
Gastro upset (esp. tetracycline)
What is the side effect of the oral contraceptive pill for acne?
Possible DVT risk
What is the controversial treatment option for acne?
Dietary modification ie. reduce glycemic load (milk, chocolate)
What is Oral Isotretinoin?
- Licensed for severe acne vulgaris (remission in ~80% of teenagers)
- Concentrated form of vitamin A
What is the effect of Oral Isotretinoin?
Reduces sebum, plugging and bacteria
What is the standard course of Oral Isotretinoin?
- 16 weeks
- 1mg/kg
List the 9 side effects of Oral Isotretinoin?
- Dry lips
- Nose bleeds
- Dry skin
- Myalgia
- Serious side effects
- Deranged liver function
- Raised lipids
- Mood disturbance
- Teratogenicity
What is the program associated with Oral Isotretinoin?
Pregnancy Prevention program (monthly tests & contraception needed)
What are the 2 clinical problems with prescribing Oral Isotretinoin?
- Expensive
2. Consumes lots of clinical time
What is Oral Isotretinoin also known as?
Accutane or Roaccutane
What is the definition of eczema/dermatitis?
Inflammation of the skin
Describe the aetiology of eczema?
Combination of genetic, immune & reactivity to a variety of stimuli
Describe the inflammation in eczema?
- Primarily due to inherited abnormalities in skin so called “barrier defect”
- Leads to increased permeability & reduces its antimicrobial function
Describe the genetic problem in eczema?
Inherited abnormality in filaggrin expression (chromosome 1) –> disordered barrier function
What are filaggrins?
Proteins which bind to keratin fibres in the epidermal cells
What are the 5 endogenous types of eczema?
- Atopic
- Seborrhoeic
- Discoid
- Varicose
- Pompholyx
What are the 2 exogenous types of eczema?
- Contact (allergic, irritant)
2. Photoreaction (allergic, drug)
Describe atopic eczema?
- Itchy inflammatory skin condition
- High Ig-E immunoglobulin antibody levels
- Genetic & immune aetiology
What is atopic eczema associated with?
Asthma, allergic rhinitis, conjunctivitis, hayfever (atopy individual)
Describe the prevalence of atopic eczema?
- 10-15% of infants affected
- Remission occurs in 75% by 15 years
- 2/3 have a family history of atopy
Describe the presentation of infant atopic eczema?
- Itchy
- Occasionally vesicular (small blisters)
- Often facial component
- Secondary infection
- Occasionally aggravated by food (ie milk)
Describe the prognosis of infant atopic eczema?
< 50% still have eczema by 18 months
What are the 2 complications of atopic eczema?
- Bacterial infection- staph aureus
2. Viral infection- molluscum, viral warts, eczema herpeticum
What are the 3 negative systemic effects of atopic eczema?
- Tiredness
- Growth reduction
- Psychological impact
List the 9 management techniques for atopic eczema?
- Emollients
- Topical steroids
- Bandages
- Antihistamines
- Antibiotics / anti-virals
- Education for parents /child
- National Eczema Society
- Avoidance of exacerbating factors
- Systemic drugs
- Newest biologic agent
What are the 2 systemic drugs that you can use for atopic eczema?
- Ciclosporin
2. Methotrexate
What is the newest biologic agent for atopic eczema?
IL4/13 blocker- Dupilumab
What is contact dermatitis?
Type 4 hypersensitivity reaction precipitated by an exogenous agent ie:
- Irritant- direct noxious effect on skin barrier
- Allergic - Type IV hypersensitivity reaction
What are the 5 common allergens for contact dermatitis?
- Nickel- Jewellery, zips, scissors, coins
- Chromate- Cement, tanned leather
- Cobalt- Pigment /dyes
- Colophony- Glue, adhesive tape, plasters
- Fragrance- Cosmetics, creams, soaps
What is Seborrhoeic Dermatitis?
Chronic, scaly inflammatory condition caused by overgrowth of Pityrosporum Ovale yeast
Where is typically affected by Seborrhoeic Dermatitis?
Face, scalp, & eyebrows occasionally the upper chest
What 2 things can Seborrhoeic Dermatitis occasionally be confused with?
- Dandruff
2. Facial psoriasis
What 2 factors makes Seborrhoeic Dermatitis worse?
- Teenagers
2. Underlying HIV
How do you manage scalp Seborrhoeic Dermatitis?
Medicated anti yeast shampoo (antifungal ketoconazole -Nizoral, Selsun)
How do you manage face Seborrhoeic Dermatitis?
- Anti-microbial, mild steroid (ie Daktacort cream)
- Simple moisturiser
What can Seborrhoeic Dermatitis rarely be treated with?
Systemic antifungals
What often improves Seborrhoeic Dermatitis?
UV/sunlight
Describe Venous dermatitis?
- Underlying venous disease
- Affects lower legs
- Incompetence of deep perforating veins
- Increased hydrostatic pressure
What are 4 ways to manage Venous dermatitis?
- Emollients
- Mild / moderate topical steroid
- Compression bandaging / stockings
- Consider early venous surgical intervention
What is the definition of psoriasis?
Chronic relapsing & remitting scaling skin disease which may appear at any age & affect any part of the skin
When does psoriasis often present?
Age onset often two peaks age 20-30y or 50-60y
What are 3 causes of psoriasis?
- T cell mediated autoimmune disease
- Abnormal infiltration of T Cells (release of inflammatory cytokines incl interferon, interleukins & TNF, increased keratinocyte proliferation)
- Enviromental & genetic factors
What are 4 things linked to psoriasis?
- Psoriatic arthritis
- Metabolic syndrome
- Liver disease / alcohol misuse
- Depression
Describe the genetic prevalence associated with psoriasis?
- 1 sibling with psoriasis: risk is 24%
- 1 parent with psoriasis: risk is 28%
- 1 sibling & 1 parent with psoriasis: risk is 41%
- 2 parents with psoriasis: risk is 65%
- Both parents & a sibling have psoriasis risk is 83 %
What genes are related to psoriasis?
PSORS genes (eg PSORS1, Chromosome 6) & HLA – Cw0602 associated in certain subtypes
List the 5 types of psoriasis?
- Plaque
- Guttate
- Pustular
- Erythrodermic
- Flexural / Inverse
What type of psoriasis is now thought to NOT be psoriasis?
Palmar/plantar pustulosis
What is Koebner phenomenon?
Psoriasis at sites of trauma / scars ie. appendectomy
Describe the presentation of psoriasis?
- Well demarcated
- Salmon pink inflammation
- Plaque build up
- No moisture
- Scaled
- Onycholysis
- Nail pitting
What 4 factors does the management of psoriasis depend on?
- Severity
- What patient wants
- What patient can cope with
- If they have arthropathy
List 3 scoring systems for psoriasis?
- Disease life quality index- DLQI
- Psoriasis area severity index- PASI
- Patient eczema severity time- PEST
What do up to 20% of psoriasis patients develop?
Arthritis
What is the treatment for psoriasis in order of increasing effectiveness & toxicity?
- Topical creams & ointments
- Phototherapy light treatment (UV)
- Acitretin- retinoid drug/ vitamin A
- Methotrexate- decrease inflammation
- Ciclosporin
- Biologic therapies
What are 4 examples of biologic therapies for psoriasis?
- Adalumimab (anti TNF)
- Ustekinumab (anti IL12/23)
- Secukinumab
- Brodilumab
Give 2 examples of topical therapies for psoriasis?
- Moisturisers- help reduce dryness, flaking
2. Steroids- reduce autoimmune response, redness, itching, inflammation
Give 4 examples of topical therapies that slow down keratinocyte production?
- Vitamin D analogues
- Coal Tar
- Dithranol- tree bark extract
- Retinoid (Tazarotene) rarely used now
What effect does Ultraviolet Phototherpy have?
- Can reduce T cell proliferations
- Encourages Vitamin D & reduces skin turnover
What are the 2 types of Ultraviolet Phototherpy?
- UV-B light is the most commonly used
2. UV-A with psoralen photosensitiser
What are the 2 risks of Ultraviolet Phototherpy?
- Short term burning
2. Longer term skin cancer
List the 3 potent side effects of most drugs for psoriasis?
- Liver dysfunction
- Hypertension
- Risk of infection
What 2 drugs would you not give for treating psoriasis?
- Azathioprine
2. Systemic steroids
What 2 distinct pathways interact or converge to cause skin cancer?
- Direct action of UV on target cells (keratinocytes) for neoplastic transformation via DNA damage
- Effects of UV on the host’s immune system
Describe the chain of damage that UV light has on skin?
DNA damage –> p53 mutation & Immune suppression & p53 induction –> Abnormal cell proliferation –> Other genetic alterations –> Skin cancer
What are the 3 main skin cancer types?
- Basal Cell Carcinoma
- Squamous Cell Carcinoma
- Malignant Melanoma
Where do melanocytes reside?
With the skin basal cells
What is the most common type of skin cancer?
Basal cell carcinoma
What is the process of creating new skin cells controlled by?
Basal cells DNA
What can a mutation in the DNA cause?
- Basal cell to multiply rapidly & continue growing when it would normally die
- Eventually the accumulating abnormal cells may form a tumour PTCH gene mutation may predispose
What are 80% of basal cell cancers found on?
Head & neck/UV exposed sites
What rarely happens in basal cell carcinomas?
Metastasis or kills
What are the basal cell carcinoma subtypes?
- Nodular
- Superficial
- Pigmented
- Morphoeic/Sclerotic
Describe Nodular Basal Cell Carcinoma?
- Nodule ie > 0.5cm raised lesion
- Shiny “pearly”
- Telangectasia / blood vessels
- Often ulcerated centrally
Describe superficial basal cell carcinoma?
- Grows slowly
- Minimal tendency to be invasive
- Erythematous
- Well-circumscribed patch or plaque
- Not ulcerative
Describe pigmented basal cell carcinoma?
- Black/dark pigment
- Curved border
- Some ulceration
- Raised
Describe Morphoeic/ Sclerotic basal cell carcinoma?
- Subtle skin textural change
- Slowly expanding
- A yellow-white waxy patch with very ill-defined edges
- Surface telangiectasia