DERM Flashcards
what should you do when performing an examination of the skin?
There are four important principles in performing a good examination of the skin: INSPECT, DESCRIBE, PALPATE and SYSTEMATIC CHECK
when you are inspecting the skin what should you note?
General observation
Site and number of lesion(s)
If multiple, pattern of distribution and configuration
when describing and examining a lesion on the skin what should you note?
SCAM
Size (the widest diameter), Shape Colour
Associated secondary change Morphology, Margin (border)
palpate the individual lesion and note the surface, consistency, mobility, tenderness and temperature
what features of a lesion would increase the likelihood of it being a melanoma?
*If the lesion is pigmented, remember ABCD
(the presence of any of these features increase the likelihood of melanoma):
Asymmetry (lack of mirror image in any of the four quadrants)
Irregular Border
Two or more Colours within the lesion Diameter > 6mm
what is a naevus?
A localised malformation of tissue structures
e.g. Pigmented melanocytic naevus is a mole
what are comedones?
A plug in a sebaceous follicle containing altered sebum, bacteria and cellular debris; can present as either open (blackheads) or closed (whiteheads)
what words are used describe the distribution of a lesion?
Generalised - All over the body
Widespread - Extensive
Localised - Restricted to one area of skin only
Flexural - Body folds i.e. groin, neck, behind ears, popliteal and antecubital fossa
Extensor - Knees, elbows, shins
Pressure areas - Sacrum, buttocks, ankles, heels
Dermatome - An area of skin supplied by a single spinal nerve
Photosensitive - Affects sun-exposed areas such as face, neck and back of hands
Koebner phenomenon - a linear eruption arising at the site of trauma
what words are used to describe the configuration of a lesion?
Discrete - Individual lesions separated from each other
Confluent - Lesions merging together
Linear - in a line
Target - concentric rigs (like a dartboard)
annular - like a circle or ring (e.g. ringworm)
Discoid/Nummular - a coin-shaped/round lesions (e.g. discoid eczema)
what is the different terminology used to describe the colour of lesions?
Erythema - Redness (due to inflammation and vasodilation) which blanches of pressure e.g. palmar erythema
Purpura - red or purple colour (due to bleeding into the skin or mucous membrane) which does not blanch on pressure. It can be petechiae (small pinion macules) or ecchymoses (larger bruises-like patches)
Hypo pigmentation - areas of paler skin
Depigmentation - white skin due to absence of melanin
Hyperpigmentation - darker skin which may be due to various causes
what is the different terminology to describe morphology of lesions?
macule - a flat area of altered colour (freckles are macular)
patch - larger flat area of altered colour or texture -(port wine stain is a patch)
Papule - solid raised lesion less than 0.5cm in diameter
Nodule - solid raised lesion greater than 0.5cm in diameter with a deeper component
Plaque - palpable scaling raised lesion >0.5cm in diameter
vesicle (small blister) - raised, clear fluid-filled lesion <0.5cm in diameter
Bulla (larger blister) - raised, clear fluid filled lesion greater than 0.5cm in diameter
Pustule - pus containing lesion less than 0.5 cm in diameter
Abscess - localised accumulation of pus in the dermis or subcutaneous tissue
Weal - transient raised lesion due to dermal oedema - e.g. in urticaria
boil/furuncle - staph infection around or within a hair follicle
carbuncle - staph infection of adjacent hair follicles (multiple boils/furuncles)
what is the terminology used to describe secondary lesions??
a secondary lesion is a lesion that evolves from a primary lesion
Excoriation - loss of epidermis following trauma Lichenification - well defined roughening of the skin with accentuation of skin markings
Scales - flakes of stratum corneum - happens in psoriasis
Crust - Rough surface consisting of dried serum, blood, bacteria and cellular debris that has exuded through an eroded epidermis (e.g. from a burst blister) - happens in impetigo
Scar - New fibrous tissue which occurs post-wound healing, and may be atrophic (thinning), hypertrophic (hyperproliferation within wound boundary), or keloidal (hyperproliferation beyond wound boundary)
Ulcer - loss of epidermis and dermis
fissure - an epidermal crack often due to excess dryness
Striae - Linear areas which progress from purple to pink to white, with the histopathological appearance of a scar (associated with excessive steroid usage and glucocorticoid production, growth spurts and pregnancy)
what does alopecia, hirsutism and hypertrichosis mean?
alopecia - loss of hair
Hirsutism - androgen-dependent hair growth in a female
Hypertrichosis - non-androgen dependent pattern of excessive hair growth
what is the terminology used to describe nails?
Clubbing - loss of angle between the posterior nail fold and nail plate - associations include suppurative lung disease, cyanotic heart disease, inflammatory bowel disease and sometimes can be idiopathic)
Koilonychia - spoon shaped depression of the nail plate - associated with iron deficiency anaemia, congenital and idiopathic)
Onycholysis - separation of the distal end of the nail plate from the nail bed - associated with trauma, psoriasis, fungal nail infection and hyperthyroidism
Pitting - punctate depressions of the nail plate
what are the functions of normal skin?
protective barrier against environmental insults temperature regulation sensation vitamin D synthesis immunosurveillance apprearance
what is the structure of the normal skin?
The skin is the largest organ in the human body. It is composed of the epidermis and dermis overlying subcutaneous tissue. The skin appendages (structures formed by skin-derived cells) are hair, nails, sebaceous glands and sweat glands.
what are the four cell types in the epidermis?
Keratinocytes - produce keratin as a protective barrier
Langerhans’ cells - present antigens and activate T-lymphocytes for immune protection
Melanocytes - produce melanin, which gives pigment to the skin and protects the cell nuclei from UV radiation induced DNA damage
Merkel cells - contain specialised nerve endings for sensation
what are the layers of the epidermis?
There are 4 layers in the epidermis, each representing a different stage of maturation of the keratinocytes. The average epidermal turnover time (migration of cells from the basal cell layer to the horny layer) is about 30 days.
Stratum Basale - basal cell layer - actively deciding cells (deepest layer)
Stratum spinous - prickle cell layer - differentiating cells
Stratum granulosum - granular cell layer - So-called because cells lose their nuclei and contain granules of keratohyaline. They secrete lipid into the intercellular spaces.
Stratum corneum (horny layer) - layer of keratin, most superficial layer
what pathology can occur n the epidermis?
a) changes in epidermal turnover time - e.g. psoriasis (reduced epidermal
turnover time)
b) changes in the surface of the skin or loss of epidermis - e.g. scales,
crusting, exudate, ulcer
c) changes in pigmentation of the skin - e.g. hypo- or hyper-pigmented skin
what is the dermis made up from?
The dermis is made up of collagen (mainly), elastin and glycosaminoglycans, which are synthesised by fibroblasts. Collectively, they provide the dermis with strength and elasticity.
The dermis also contains immune cells, nerves, skin appendages as well as lymphatic and blood vessels.
what pathology can occur in the dermis?
changes in the contour of the skin or loss of dermis e.g. formation of
papules, nodules, skin atrophy and ulcers
disorders of skin appendages e.g. disorders of hair, acne (disorder of
sebaceous glands)
changes related to lymphatic and blood vessels e.g. erythema
(vasodilatation), urticaria (increased permeability of capillaries and small venules), purpura (capillary leakage)
what are the different types of hair?
a) lanugo hair (fine long hair in fetus)
b) vellus hair (fine short hair on all body surfaces)
c) terminal hair (coarse long hair on the scalp, eyebrows, eyelashes and
pubic areas)
what is a sebaceous gland?
sebaceous glands produce sebum via hair follicles - they secrete sebum onto the skin surface which lubricates and waterproofs the skin
the sebaceous glands are stimulated by the conversion of androgens to dihydrotestosterone and therefore become active at puberty.
pathology of sebaceous glands may involve increased sebum production and bacterial colonisation e.g. acne. Also may involve sebaceous gland hyperplasia
what are sweat glands?
sweat glands regulate body temperature and are innervated by the sympathetic nervous system
they can be eccrine and apocrine sweat glands
Eccrine sweat glands are universally distributed in the skin
Apocrine sweat glands are found in the axillae, areolae, genitalia and anus and modified glands are found in the external auditory canal. They only function from puberty onwards and action of bacteria on the sweat produces odour.
what are the stages of wound healing?
Wound healing occurs in 4 phases: haemostasis, inflammation, proliferation and remodelling
Haemostasis - vasoconstriction and platelet aggregation and clot formation
Inflammation - vasodilation, migration of neutrophils and macrophages, phagocytosis of cellular debris and invading bacteria
proliferation - granulation tissue formation and angiogenesis , re-epithelialisation
Remodelling - collagen fibre re-organisation, scar maturation
how should you manage an emergency in dermatology?
full supportive care - ABC of resuscitation
withdrawal of precipitating agents
management of associated complications
specific treatments for specific conditions
what are some causes of urticaria, angiooedema and anaphylaxis ?
can be idiopathic food (nuts, sesame seeds, shellfish, dairy products) drugs (penicillin, contrast media, NSAIDs, morphine, ACEi) insect bites contact - e.g. latex viral or parasitic infections hereditary autoimmune
what is urticaria?
Urticaria is due to a local increase in permeability of capillaries and small venules. A large number of inflammatory mediators (including prostaglandins, leukotrienes, and chemotactic factors) play a role but histamine derived from skin mast cells appears to be the major mediator. Local mediator release from mast cells can be induced by immunological or non-immunological mechanisms.
how does urticaria present?
swelling involving the superficial dermis, raising the epidermis
itchy wheals
how does angioedema present?
deeper swelling involving the dermis and subcutaneous tissues
how does anaphylaxis present?
bronchospasm, facial and laryngeal oedema, hypotension; can present initially with urticaria and angioedema
how is urticaria managed?
antihistamines
how is severe acute urticaria and angioedema managed?
corticosteroids
how is anaphylaxis managed?
adrenaline
hydrocortisone and chlorphenamine
what is erythema nodosum and what causes it?
a hypersensitivity response to a variety of stimuli
causes by group A beta-haemolytic streptococcus, primary TB, pregnancy, malignancy, sarcoidosis, IBD< chlamydia and leprosy
how does erythema nodosum present?
discrete tender nodules which may become confluent
lesions continue to appear for 1-2 weeks and leave bruise like discolouration as the resolve
lesions not ulcerate and resolve without atrophy or scaring
the shins are the most common site
what is erythema multiforme?
how does it present?
it is often of unknown cause, it is an acute self-limiting inflammatory condition with HSV being the main precipitating factor
other infections and drugs are also cause
there are target lessons
initially seen on the back of the hands/feet before spreading to the torso, upper limbs are more commonly affected than lower limbs, pruritus is occasionally seen and s usually mild
what is Stevens-Johnson syndrome and toxic epidermal necrosis?
Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are a spectrum of the same pathology, where a disproportional immune response causes epidermal necrosis, resulting in blistering and shedding of the top layer of skin. Generally, SJS affects less that 10% of body surface area whereas TEN affects more than 10% of body surface area.
Certain HLA genetic types are at higher risk of SJS and TEN.
what are the causes of SES and TEN?
Medications Anti-epileptics Antibiotics Allopurinol NSAIDs
Infections Herpes simplex Mycoplasma pneumonia Cytomegalovirus HIV
