Integ1 Flashcards
What are the functions of skin?
- barrier
- homeostasis
- insulation
- sensation
- vitamin D production
What are the three basic layers of the skin?
- thin epidermis
- thicker dermis
- subcutis
What is the stratum basale?
the layer at the base
these are the stem cells that proliferate - they divide, pushing upwards.
It takes 10-14 days to go from stem cells to flattened top cells.
What is the stratum spinosum?
the spiny layer
There are lots of desmosomes which act as plates to hold the cytoskeletons of two cells tighter, making it strong and a good barrier. These cells get flatter and flatter towards the top.
A friction blister occurs due to damage in the stratum spinosum layer. Initially, fluid builds up due to burst cells, and later some transudate.
What is the stratum granulosum?
the granular layer
the cells are very flat in this layer. There are keratohyalin granules (keratin precursor) and lamellar bodies (lipids)
What is the stratum corneum?
the horny layer
contains keratin-packed enucleated cells –> NB soft keratin (nails)
lipids from lamellar bodies act as mortar, holding the cells packed with keratin together.
What is the stratum lucidum?
the clear layer
this layer is only found in thick skin. it contains immature keratin (eleidin).
What is there within the epidermis?
- melanocytes
- langerhans cells
- merkel cells
What are melanocytes?
- pigmentation
- in stratum basalis
- every shade of hair and skin is just a mix of two melanins (think of vitiligo)
What are langerhans cells?
- immune cells
- antigen presenting cells
- in stratum spinosum
- when it goes wrong it can cause eczema - attacks the wrong cells
- protection against microorganisms
- small, pale cells in non-basal layers of skin
- they are dendritic cells - have branching cytoplasmic processes
- they are antigen presenting cells and form a network in the epidermis - part of the immune system
What are merkel cells?
- sensory
- associated with nerve endings
- in stratum basalis
What are examples of appendages?
HAIR FOLLICLES: erector pili muscle
SWEAT GLANDS: eccrine and apocrine
SEBACEOUS GLANDS: holocrine
What kind of glands are there?
MEROCRINE: exocytosis
APOCRINE: clinch bits off themselves
HOLOCRINE: apoptosis/explode
What can vitamin D deficiency result in?
Children: rickets
Adults: osteomalacia
What is meant by integument?
means the skin, hair and nails. it is the interface between the body and the environment - thus is subject to a wide range of insults/stresses
What is the importance of keratin in protection and adaptation?
–> cell flow in the epidermis
Stratum corneum: cornfield keratinocytes lose nuclei, continuing to move distally
Daughter cells move distally through the epidermis while differentiating into mature keratinocytes - making lots of the tough, waterproof protein keratin
Basal layer: first cell layer, containing dividing stem cells
Nail is also made of keratinocytes, and is full on keratin. Horns and hoofs are also keratin(-ocytes).
What can extensive epidermal damage lead to?
- dehydration and shock
- infection
- heat loss and hypothermia
- protein loss, electrolyte imbalance, high-output cardiac failure, renal failure
What does the skin act as a barrier to/protect against?
- irradiation and UV light
- physical trauma
- microbes
- allergens
- irritants
- heat
- cold
- infections
What does epidermal melanin do?
UV protection
the colour of human skin is due mainly to melanin (dark skin) and haemoglobin (light skin)
much normal genetic variation in the amount of melanin (>12 genes known)
melanin protects against DNA damage and this skin cancer, especially in dark skin, incidence only 8-10% that of white people
melanin is made by melanocytes - cells in basal epidermal layer, with dendrites that feed pigment to keratinocytes
What happens during tanning?
- melanocytes increase activity - they make and transmit more melanin
- the signal for this works through DNA damage by uv
- gives some protection against uv
- additional protection by skin thickening in response to uv
What is lichenification?
more extreme form of hyperkeratosis - reaction to excessive rubbing or scratching/skin conditions
What is sunburn?
sunburn is a radiation burn causing blisters, inflammation and cell death (severe dna damage).
if you have ever been sunburnt it increases your risk of skin cancer
What are naevi?
MOLES
singular: naevus
benign proliferation of melanocytes
many of large naevi = risk factor for melanoma skin cancer
What are ephelides?
FRECKLES
involve a genetic component
also linked to red/fair hair
sun exposed areas
What are visual cues of solar lentigos?
liver spots, age spots, age related
What is solar keratoses?
dysplastic growth of keratinocytes
What are the two types of carcinoma?
- squamous cell carcinoma
- basal cell carcinoma
Why is UV good?
UV is needed for vitamin D production in skin.
UV radiotherapy is used for skin conditions such as vitiligo and psoriasis
What is irritant contact dermatitis?
- occurs when too much exposure to a substance
- can still use it, but reduce amount
- people vary in sensitivity
- common
- any of redness, itching, swelling, blistering and/or scaling
What is allergic contact dermatitis?
- allergy to something that contact skin - immune system involved
- tiny amount may be sufficient
- relatively uncommon
- varies greatly between people. may develop after long or short use
- any of redness, itching, swelling, blistering and/or weeping
What are examples of microbes?
- fungi
- bacteria
- viruses
What is paronychia?
nail fold infection - fungal or bacterial
fungal example: tine wapitis, scalp ringworm
virus example: HPV warts
Portal of entry: microbes can enter breach in epidermis (e.g. streptococcus in cellulitis)
Impaired immunity predisposes to infection, e.g. HIV and viral warts, eczema herpeticum or herpes (cold sore) virus infecting eczema
What is eczema?
An inflammatory process affecting the skin and due to various factors, both internal and external.
Interchangeable with the term ‘dermatitis’.
What is atopic eczema?
The most common form, affects 15% of the population. In children the majority of onset is
What is the histology of atopic eczema?
ACUTE STAGE: oedema of the epidermis (spongiosis), intraepidermal vesicles form, which coalesce/form blisters/rupture
CHRONIC STAGE: los of vesicles, epidermis thickens; stratum spinosum-acanthosis, stratum corneum-hyperkeratosis
What are symptoms of infantile atopic eczema?
- widespread dry red scaly skin
- can be weeping
- often cheeks are first area affected
- nappy area spared - moisture effect
What are the symptoms of atopic eczema in toddlers/school age children?
- more localised (flexural) and thickened, leathery (lichenified) lesions
- scratch marks
- elbows, knees, eyelids, ear creases, neck, scalp
What are the symptoms of atopic eczema in adults?
- commonly persistent localised eczema
- recurrent secondary staphylococcal infection
- major factor for irritant contact dermatitis, particularly hands
What is the treatment of atopic eczema?
- trigger avoidance
- break the itch-scratch-itch cycle
- regular emollients (moisturisers)
(consistency regulated to oil/water content –> lotion (oil in higher water content preparation), cream (oil in lower water content preparation), ointment (oil-based preparation)) - soap substitutes - aqueous cream, emulsifying ointment, dermal 500 (with antimicrobial)
- bath preparations (oilatum, balneum, dermal 600)
- intermitted topical steroids:
1% hydrocortisons (mild)
eumovate (moderate)
betnovate, elocon (potent) - other: topical calcineurin inhibitors (tacrolimus), oral antibiotics, antihistamines
When should someone be referred to a dermatologist in the case of atopic eczema?
- diagnostic uncertainty
- severe eczema or poor response to topical therapy for consideration of: UV phototherapy, systemic treatment - cyclosporin, methotrexate, azathioprine
What are possible complications of atopic eczema?
- bacterial co-infection - impetiginisation
- viral co-infection - eczema herpeticum
- post-inflammatory hypo pigmentation/hyperpigmentation
- scarring
- striae/skin atrophy from steroid use
- depression/psychosocial impact
What is psoriasis?
a common (1-2% of the population) chronic inflammatory disorder. It has focal, well-maintained, inflamed, oedematous plaques covered with silvery-white scale. Psoriasis can affect any age and there is no significant male/female difference.
The distribution of psoriasis comes in a variety of shapes and sizes. It is symmetrical and appears on extensor surfaces, sacrum, scalp, ears, palms, soles. There are environmental, genetic and immunologic factors.
What is the histology of psoriasis?
- disordered maturation of keratinocytes and reduced epidermal transit time from 30 days to 6 days
- leads to hyperprolifertion and thickening of the epidermis
What is the treatment of psoriasis?
- topical
- emollients
- topical steroids
- coal tar
- salicylic acid
- vitamin D analogues (calcipqotriol - dovonex)
- combination of above - diprosalix, dovobet)
- dithranol
What would you refer a psoriasis case to a dermatologist for?
PHYSICAL: UV phototherapy
SYSTEMICS: ciclosporin, methotrexate, acitretin
BIOLOGICS: monoclonal antibodies against TNF - ethanercept (Enbrel), infliximab (remicade) and adalimumab (humira), monoclonal antibody against IL-12 and IL-23 - urstekinumab (stellar), must meet specific criteria based on disease severity and impairment of quality of life, and failure of other systemics
What is acne vulgaris?
- Affects the areas of skin with the densest population of sebaceous follicles
- Over-activity of polo-sebaceous units secondary to hormonal stimulation
- Hyper proliferation of follicular epidermis with subsequent follicle plugging
- Presence and activity of Propionibacterium acnes with the above setting
What is the treatment of acne vulgaris?
- topical retinoids (adapalene, tretinoin)
- topical antibodies(dalacin-T, zineryt)
- benzoyl peroxide (Duac)
- oral antibodies (erythromycin, oxytetracycline, lymecycline)
- oral contraceptive pill (Dianette)
Referral to specialist dermatologist for consideration of Isotretinoin (Roaccutane):
- systemic retinoid
- works against all contributing factors
- teratogenic - two forms of contraception, monthly pregnancy tests
- other side effects: dry lips and skin, myalgia, hair thinning, depression
- base line FBC, LFTs and lipids
What is impetigo?
- most common bacterial skin infection in children; bacterial skin infection with staphylococcus aureus ± streptococcus pyogenes
- begins with a single erythematous macule which rapidly evolves into vesicle or pustule then ruptures
- exudate dried to fold classic golden crust
- if mild and localised - topical Fucidin
- if extensive - oral Flucloxacillin
What are viral warts?
- growths caused by infection with HPV (>70 subtypes)
- spread by direct or indirect contact - swimming pools, biting fingernails, shaving
- incubation ranges from a few weeks to over a year
- contagious but low risk of spread
- treatment: nil/self-resolving, duct tape, salicylic acid, cryotherapy
What is tinea?
- the most common organism is the dermatophyte trichophyton rubrum
- clue is history - short history, very itchy
- slowly enlarging, annular, scaly, erythematous plaque with well-defined edge and central clearing
- under microscopy - hyphae visible
What is the treatment of tinea?
- topical azalea (eg clotrimazole) or allylamine (eg terbinafine) for two weeks
- systemic therapy may be indicated if extensive, immunosuppression, resistance to topical therapy
- nails; terbinafine for 6 weeks (fingernails) or 3-4 months (toenails)
- monitoring for adverse effects and drug interactions
What is actinic keratosis?
- common sun-induced scaly or hyperkeratotic lesion, which has the potential to become malignant
- affects 23% of the UK population >60 years
- consequences of cumulative long-term sun exposure, so incidence increases with age
- also risk in long-term phototherapy (e.g. psoriasis) and immunosuppressed patients
- genetic factors/skin type important
What is the treatment for actinic keratosis?
Largely managed in the community
Treatment:
- observation
- emollients
- cryotherapy
- 5-fluorouracil cream (Efudix), imiquimod cream (Aldara), Diclofenac gel (Solaraze)
Should be referred to a dermatologist if:
- diagnostic uncertainty
- suggestion of transformation into SCC (under 2ww) - e.g. growth, pain, bleeding
What is the histology of actinic keratosis?
- abnormality confined to epidermis only
- clusters of atypical keratinocytes at lower layer of epidermis
- once this involves full thickness of epidermis = Bowen’s
What is squamous cell carcinoma?
- the result of cumulative sun exposure, so incidence increases with age
- sun-exposed sites - dorsum of hands, forearms, ears, upper face, lower lip
- arise de novo or from AK/bowens
- also site of chronic inflammation e.g. chronic leg ulcer
- refer immediately under 2ww for surgical intervention
What is the histology of squamous cell carcinoma?
- invasion of islands of typical squamous cells into the dermis
- classed as well, moderately, or poorly differentiated
- assessment of how significantly the tumour cells differ from normal keratinocytes
- lips and ears have a higher rate of metastasis to lymph nodes
What is basal cell carcinoma?
- slow growing skin malignancy also known as a ‘rodent-ulcer’
- head and neck most common
- shiny, translucent, nodule with a rolled-edge, telangiectasia, central depression or ulceration
What is the histology of basal cell carcinoma?
nests of basiloid tumour cells, palisading of cells at periphery
What is the treatment of basal cell carcinoma?
- routine dermatology referral (not 2ww)
- treatment usually by excision
- GP follow up, education regarding sun awareness and skin surveillance
What are suspicious pigmented lesions?
- think about risk factors
- counsel about risk
- at risk groups: educate about sun awareness, skin surveillance…
Asymmetry Border irregularity Colour variation Diameter >6mm - and persistent growth Extra features - itching, bleeding
Other suspicious features: bleeding without trauma, new nodularity, new pigmentation or unexplained destruction of a nail, new pigmentation on the lips or mucous membranes
What is melanoma?
- over 12,000 new cases in 2010 (rate doubled in past 20 years)
- second most common cancer in the 15-34 year age group
- most common on the trunk (males) and legs (females)
- types: nodular, superficial spreading, lentigo maligna, acial lentiginous
- all suspicious lesions should be referred under the 2 week wait rule
What is the histology of melanoma?
- varies depending on melanoma subtype
- atypical melanocytes arranged singly or in nests
- invasion into the dermis and subcutaneous fat
- depth of invasion is major prognostic indicator (breslow thickness)
