assessment of dermatological skinpadas fk ukd

8/11/2019 Assessment of Dermatological SkinPADAS FK UKD

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Assessment OfDermatological Skin

PADAS FK UKRIDADr. H.W.WONG Dip.Derm.

Dermatology Department

Medical FacultyChristian University of Krida Wacana



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1. Overview of structure and function of the skin

The functions of the skin are complex. They include thefollowing :

• The epidermis prevents water loss by evaporation

• The dermis reduces risk of significant external injury.

• Dermal blood flow maintains the epidermis andpermits body cooling via sweat glands and alterationsin surface blood flow.

• The skin also plays a vital role in immunesurveillance.

• Ultraviolet light protection.

• Energy storage.• Sensory information.

• Provides subtle signals associated with sexualsignalling.



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Epidermis

This is approximately 0.1mm thick.

It acts as a barrier by

• Preventing water loss.

• Preventing UV damage.

• Preventing toxin, antigen and pathogen invasion.



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Epidermis

It consists of :

• Basal layer.

It is a 1 to 3 cells thick layer of proliferating stem cells.

At cell division, one daughter cell goes on to become adifferentiating keratinocyte whilst the other remains as anundifferentiated stem cell.

It has pigment-producing melanocytes.• Prickle cell layer or stratum spinosum.

Keratinocytes in the spinous and granular layer produce keratin.

Keratinocytes are joined together by desmosomes.

• Granular cell layer or stratum granulosum.

Keratinocytes in this layer produce a lipid-rich material which isextruded onto the cell surface via membrane-coating granules(syn. lamellar bodies, Odland bodies) formed on the Golgiregion of the cell.

• Stratum corneum

This layer provides most of the barrier function of the epidermis.



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Other functions of the epidermis

a) It is thickest on the palms and the soles due to thicker stratum

corneum.b) In the epidermis, UVB irradiation converts epidermal 7-dehydrocholesterol ultimately into vitamin D3, which is transported by abinding protein into the circulation.

c) Pigment-producing melanocytes are situated within the basal layer ofthe epidermis from where they transfer melanin into surroundingkeratinocytes, where it is stored in packages or melanosomes.

d) A significant proportion of natural photoprotection is also provided bythe stratum corneum, which becomes thicker in response to repeated UVexposure. This natural sun screening effect is particularly important in skintype 1 individuals who never tan but nevertheless achieve a degreeof photoprotection on chronically exposed sites.

e) Dendritic Langerhans cells are also present in the epidermis. These

make up part of the skin associated lymphoid tissues (SALT) and actas the furthest outpost of the immune system. They are the principle antigenpresenting cells in allergic contact dermatitis.



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Dermoepidermal junct ion

The junction between the dermis and epidermis is a complex structure called the

basement membrane zone (BMZ). Here the epidermis is literally stuck or held ontothe underlying dermis. Many blistering diseases are the result of abnormalities in theultrastructure of this zone.

The basement membrane zone consists of:

a) Hemidesmosones : These are focal thickeningsin the basal plasma membrane of keratinocytes.

They maintain adhesion between the epidermisand the dermis. They consists of :

• An intracellular component, the attachment plaque, which is associated withtonofilaments in the basal cell.

• An extracellular component, the sub-basal dense plate, which is located inthe lamina lucida.

b) The basement membrane : which has 3 layers

• Lamina lucida – consists of vertical anchoring filaments.• Lamina densa – lies parallel to and below the lamina lucida.

• Lamina fibroreticularis – this has anchoring fibrils which are attached to thelamina densa and the upper part of the dermis.



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Dermis

Structure of the dermis

• It is bounded distally by its junction with the epidermis and proximally bythe subcutaneous fat.

• The dermis is the fibrous part of the skin consisting chiefly of collagenproduced by fibroblasts.

• Dermal thickness varies with body site, e.g. thick on the back (4mm)and thin around the eyes (<1mm)

• Functions of the dermis• It acts as a barrier against physical trauma.

• It supports the contained blood vessels, nerves and lymphatics.

• It provides nutrition to the epidermis. Blood vessels stop at the BMZ sothat the epidermis has to be supplied with nutrients and oxygen bydiffusion; hence the limited thickness of the epidermis.



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Cutaneous blood flow

• Blood supply to the skin is believed to be delivered by regularly

spaced, vertically orientated arterioles that each supplies abroadly circular-shaped area of skin at the surface.

• The haemoglobin contained in dermal blood vessels is asignificant pigment or chromophore in the skin, responsible forthe pink component of skin colour.

• The borders between adjacent areas of supply thus receive

blood that has a lower oxygen content and flow rate compared tothe area immediately around the central feeding vessel.

• This pattern of blood supply to the skin leads to the marbled orreticulate (net-like pattern) purplish discolouration of cold skinseen on otherwise healthy individuals who have become cold(i.e. physiological livedo reticularis).



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Adnexal structures

a) Pilosebaceous glands

• Each gland contains a hair follicle and sebaceous gland, the relative size ofeach varying with the anatomical site.

• Function of hair is chiefly self-adornment.

• Scalp hair is useful for sun protection

b) Eccrine sweat glands

• They are present all over the skin but the duct openings are only visible withthe naked eye on the fingers and toe pads.

• Evaporation of sweat results in loss of latent heat of vaporization, resulting incooling of the skin.

c) Apocrine sweat glands

• They are only found in the axillae, scalp and groin.

• Their function is presumably chiefly related to scent or pheromoneproduction.

d) Facial musculature

• It attaches to skin and enables a vast range of non-verbal signals to beimparted.

• These, along with hair, nails, and body odour production by apocrine glands,contribute to the rich variety of social signalling produced by the skin andused by humans.



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2. Impact of skin disease on quality of life

• Chronic skin disease can have a devastating impact on the patient's life.

• As most skin diseases are not associated with significant mortality, skin diseasemay be disregarded when competing with life-threatening diseases for limited

funds.• To overcome these problems, various quality of life measures have been

developed. These include:

Disease specific questionnairese.g. for psoriasis, acne, eczema.

Dermatology specific questionnaires These can be used in any skin disease toprovide an overall measure of disease impact.

Quality of life questionnaires

These take into account the effect a skin disease has on the patient'sphysical ability, their self-esteem, job opportunities, sex and social life.

Compared to objective measurements they give a more realistic estimateof the impact of the disease on the patient’s life, e.g. psoriasis extent mayreduce by half after treatment, but if the same site is still affected thepatient might not perceive this as a useful improvement.

They can be used for clinical, research, audit purposes and to win

additional resources for the sufferers.



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3. Taking a dermatological history

• The history is a complex and selective process based on avariety of factors that stem from an understanding of the

implications of the diagnosis.• A more detailed history may be required after a working

diagnosis is made to elucidate the cause or plan therapy.

• A structured dermatology history is suggested, though rigid oruncritical adherence to all its components is not required in every

patient.• One must take into account the limitations of the person's

descriptive powers and recall.

• Some patients need to be encouraged to express their theoriesabout causation and therapy in order to ensure that what he orshe perceives as important factors have not been overlooked.



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4. Examining a dermatology patient

• The patient must be warm and comfortable.

• The doctor needs good lighting, magnification and adequate exposureof the affected area.

• A patient with a solitary lesion rarely needs to be fully undressed andfrequently only the lesion and adjacent anatomy need to be examined.

• A patient with a rash needs to be examined fully, when they are lyingflat.

• The correct couch height enables the doctor to make unhurried andadequate observations.

• Always examine both hands and feet, if these sites are involved, toexclude an id reaction(an allergic type reactive eczema that occurs at distant sites insomeone with a fungal infection, usually of the feet) or endogenousrashes (e.g. hand and foot eczema or psoriasis) that superficiallyappear to be exogenous.

• General examination of all systems is rarely required but an

examination of relevant organ systems must be made, e.g. peripheralpulses in leg ulceration, and draining lymph nodes and organomegaly inpatients with potentially metastatic tumours.



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Explanation of terms used in examination (plaque, nodule etc.) with photographicexamples

Macules

• A macule is a flat (i.e. not palpably raised) coloured lesion, usually red, brown ordepigmented.

• Any associated fine scale indicates abnormal keratinocyte function as well asmelanocyte or blood vessel involvement.

• Example: Lentigo simplex. This benign, flat, tan-coloured epidermal macule isdue to a localised increase in basal epidermal melanocyte numbers.

Papules

• A papule is a palpably raised lesion <1cm in diameter

Nodules

• A nodule is a palpably raised lesion >1cm in diameter.

• Most of the nodule may lie beneath the skin surface (e.g. lipoma).

• Example: Basal cell carcinoma (BCC) pearly telangiectatic nodule. Sometimesthe centre of the tumour degenerates, producing central necrosis, so that onlythe edge is raised up forming the so-called rolled edge.

Plaques

• Plaques are flat-topped, slightly raised, or palpably different areas of skin; scalingis commonly present.

• Example: Psoriasis. Scaly, well-defined red plaques are characteristic ofpsoriasis.

4 Examining a dermatology patient



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Weals

• Weals are the result of rapid leak offluid from the blood vessels into the dermis.

• Vessels and lymphatics quickly reabsorb this fluid so that in simple urticaria theindividual weals last for less than 24 hours, althoughnew weals may be continually formed.

• The whole episode may last for many daysif not controlled by oral antihistamines.

Differential diagnoses of Wealsa) Urticaria

• The weals can adopt any shape and size and may appear as papules, nodules,annular or arciform lesions.

• They do not show any surface changes as they are entirely due to dermal

oedema.• They do not last for more than 24 hours as vessels and lymphatics quickly

absorb the dermal fluid.

• Idiopathic urticaria. Urticaria has a variety of causes but commonly no cause isfound. Patients develop multiple raised, itchy, red weals.

b) Urticated plaques or papules

• Here the weals last for more than 24 hours.

• They occur in conditions like vasculitis, lupus erythematosus and some drugreactions.

c) Weals with surface changes

• This indicates presence of associated epidermal disease and is therefore notsimple urticaria.

d) Blisters

• Patients often mistakenly describe weals as blisters.

• Blisters leak fluid and collapse when pricked, weals do not.



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Vesicles

• These are small fluid filled blisters, < 5mm in diameter.

• They are usually intra-epidermal.

• Example. acute eczema

Bullae

• These are large fluid filled blisters, > 5mm in diameter.

• Bullae and vesicles contain fluid and when pricked, the liquid leaks outand the blister collapses.

• They can arise within the epidermis, e.g. pemphigus vulgaris, or justbeneath the epidermis, e.g. dermatitis herpetiformis or bullous

pemphigoid where blisters arise on an urticated basePustules

• Pustules result from the accumulation of large numbers of leukocytes inthe epidermis or upper dermis.

• Surface pustules have a turbid yellowish colour.

• Pustules can begin either as clear-fluid-filled blisters which then attract

pus cells (e.g. Herpes simplex), or directly by accumulation ofpolymorphs e.g. acne, pustular psoriasis.

• A deeper collection of pus produces a palpable nodule or abscess andthe yellow pus is not visible.



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Erosion, Ulcer, Fissure And Excoriation.

Ulcers, erosions, excoriations and fissures represent breaks in the skin surface:

• Erosions are produced by surface loss chiefly involving only the epidermis, e.g. aburst bullous pemphigoid blister.

• Ulcers extend the tissue loss into the dermis, e.g. leg ulcer.• A fissure is a narrow, deep, cleft-shaped ulcer, e.g. angular cheilitis.

• Excoriations are scratch marks. They may result in erosions or ulcers.

Scale

• Surface scale or flaking of the skin is the result of loss of a damaged stratumcorneum (e.g. a fungal infection or abnormal stratum corneum (e.g. psoriasis).

• Do not confuse with hyperkeratosis, i.e. thickening of stratum corneum, whichcan occur with scaling, e.g. psoriasis, or without scaling, e.g. a keratin horn

• The presence of scaling indicates an abnormality of the epidermis.

• When scratched, a scale usually fragments into layers and becomes whiter.

Crust

• A crust, or scab, is a dried surface exudateof blood or serous fluid.

• It is usually a single adherent scab that can be picked off.

• The presence of a crust indicates that tissue fluid or blood has leaked throughthe epidermis as a result of inflammation or some other abnormality of theepidermis.

Scaling and crusting may be difficult to distinguish and the two may occur together,e.g. Bowen’s disease



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Atrophy

Atrophy indicates thinning of epidermis, dermis, or both.

• Dermal Atrophy

This results in loss of collagen, the major component of the dermis.The skin feels thinner and becomes more transparent so that blood vessels,tendons, etc. can be seen through it.

The body sometimes reacts to dermal atrophy by producing scar tissue (e.g.lichen sclerosis et atrophicus) although scarring and atrophy are not the same.

Example: Topical corticosteroid induced dermal atrophy.

Leads to loss of dermal collagen; the skin is thinner and transparent.

This is frequently associated with steroid induced purpura.

Purpura results because blood vessels are not properly supported by, orpacked around with, normal collagen, so that a small shearing force easilyresults in the blood vessel bursting.

• Epidermal atrophy

Epidermal atrophy results in a featureless, often shiny, hairless skin surface.

Sclerosis (Hard Skin)• Sclerotic skin feels firm and indurated, but it may look relatively normal.

• The surface of the sclerotic skin is often white and shiny with loss of skin ridgesand markings.

• Sclerosis can occur due to:



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An expansion of the collagen by ground substance material (e.g. mucin)

A change in the collagen quality, e.g. the increased cross-linking betweenindividual collagen fibres that occurs in insulin-dependent diabetes.

An increase in the amount of dermal collagen, e.g. in morphoea. Hereinflammation within the dermis and epidermis results in a damaged andhardened dermal collagen. On the fingers the loss of normal skin mobility means

that the skin may appear to be thickened rather than just immobile and hard.Erythema, Telangiectasia, Purpura, Petechiae and Ecchymosis

These result from changes in dermal blood vessels.

• Erythema is diffuse redness caused by vasodilatation and/or increased bloodflow in vessels deep in the skin so that the individual vessels are not visible.

• Telangiectasia are distinguishably visible vessels close to the surface.

• Purpura is caused by blood that has leaked from dermal blood vessels andtherefore cannot be blanched by pressure.

• Pinpoint spots of purpura are called petechiae; extravasated blood in fat andmuscle is an ecchymosis or bruise.

Poikiloderma

This is the combination of atrophy, pigmentation and telangiectasia and may occur afterradiation therapy to the skin.



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Shapes and patterns

a) Discoid or Nummular

• These are circular or coin-shaped lesions, e.g. discoid eczema and psoriasis.

• In solitary discoid lesions the edge or border is characteristically regular inbenign conditions (e.g. in psoriasis) and irregular in malignant conditions (e.g. inBowen's disease).

b) Annular

• This describes a ring shape and can be produced by many skin conditions.

• Annular urticaria lesions are non-scaling and come and go within 24 hours.

• Erythema annulare centrifugum lesions have a trailing scaly edge and takeweeks to change.

• Fungal annular lesions are diffusely scaly with a scaly trailing edge and changein weeks to months.

c) Target

• Concentric rings of different colours or shades occur in vascular-basedinflammatory conditions

• Occurs presumably because the effect of the vascular insult has differentconsequences at different distances from the central damaged vessel e.g.erythema multiforme, vasculitis, lupus erythematosus and urticaria.



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d) Oval and Digitate

• These are often seen together in exanthematous rashes.

• On the trunk these are usually uniformly aligned with long axes orientateddownwards and outwards. The best example is the fir-tree pattern seen inpityriasis rosea.

• Digitate lesions are more elongated ovals, and typically occur in digitatedermatosis, a benign variant of chronic superficial dermatitis or parapsoriasis.

e) Serpiginous, Rippled or Gyrate

• These 3 terms describe wavy line variants.

• A serpiginous or snake-like wavy line is the pattern left by larva migrans andscabies mites as they burrow through the skin.

• Rippled or gyrate describes a series of wavy but parallel lines.

f) Dermatomal

• Rashes (e.g. herpes zoster, zosteriform psoriasis) or lesions (e.g. epidermalnaevus) may follow a dermatome distribution.



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g) Reticulate, Livedo And Cribriform

• These terms describe the net-like pattern that may be seen in certain rashes,erythema and scarring respectively.

• Reticulate (retiform) describes a lace-like pattern of a rash (e.g. RothmannThompson Syndrome), or of individual lesions (e.g. Wickham’s striae in lichen

planus)• Livedo mottling

This describes the reticulate pattern produced by the inequalities of cutaneousblood supply that arise as a consequence of the pattern of skin vascularsupply.

The darker areas result from deoxygenated blood flow in the low flow orwatershed areas between the higher flow, central, pink areas that are bettersupplied with blood by the feeding arteriole.

Diseases may be selectively localised into these low blood flow areas, e.g.polyarteritis nodosa.

• Cribriform describes a colander or sieve-like pattern of scarring seen in areas ofresolved pyoderma gangrenosum.



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Arrangements of multiple lesions.

a) Grouped lesions

• Grouped lesions are multiple but separate lesions centred around onearea – for example, insect bite reactions and herpes simplex virusinfection.

b) Scattered and disseminated

• Multiple lesions at different sites without any other specific patterns aredisseminated (small lesions) or scattered (irregular lesions).

c) Exanthematous

• Exanthematous describes the multiple, red, usually truncal, scalylesions that occur in some drug eruptions or viral exanthems. Theyusually do not have the same uniform fir-tree pattern of distribution seenin pityriasis rosea.

d) Confluent

• Multiple lesions becoming merged together – either because there areso many or the individual lesions have enlarged – are called confluent,for example, pityriasis versicolor and psoriasis.

e) Erythroderma

• This describes total, or virtually total, redness of the skin as a result ofeczema, psoriasis, drug eruptions, Sezary syndrome or other rarer skindiseases (e.g. pityriasis rubra pilaris and lichen planus).



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Other useful patterns

a) Symmetry and asymmetry

• A symmetrical distribution (e.g. psoriasis, atopic dermatitis, viral exanthemata)

implies an endogenous or systemic cause of the rash. An asymmetrical rashsuggests the possibility of an exogenous cause, such as a skin infection andfungal infection in particular.

b) Photosensitive

• Skin reactions caused by sun exposure affect the face, nape and V of the neck,and dorsum of the hands and arms. Characteristically there is sparing ofnaturally shaded sites.

c) Linear, angulated or geometric shapes

• Geometrically shaped lesions – for example, linear, square, perfect circles, oroddly shaped – should raise the possibility of an external cause, especially if thesurface is eroded or ulcerated.

• The injury may be accidental in normal or fragile skin, or deliberately induced bythe patient (i.e. dermatitis artefacta) or others (i.e. non-accidental injury inchildren). Remember the odd patterns produced by reactions to adhesivedressing plasters and so on.

d) Sparing• Observing which body sites are not affected by a rash can be diagnostically very

helpful.

• Patients with generalised pruritus, scratch very vigorously, producing multipleexcoriations. However, the observation that areas are spared where the patientcannot reach to scratch (usually the upper back) demonstrates that the visiblechanges are a result and not a cause of the itch.

• Similarly, sparing in sun-protected sites in a light-induced or light-aggravateddermatosis, or the selective involvement of skin flexures in airborne contactallergic reactions, can be helpful.



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5. References

• Finlay AY. Quality of life measurement in dermatology: a practical guide. Br J

Dermatol.1997 Mar;136(3):305-14.

• Ashton R The art of describing skin lesions

Part 2 Dermatology in Practice May/June 1998.

• Ashton R The art of describing skin lesions Part 3 Dermatology in Practice

July/August 1998.

• Physical Signs in Dermatology, 2nd ed. Clifford Lawrence, Neil H Cox. Mosby,

London, 2001 ISBN 0-7234-3184-1

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