Description of Dermatological Lesions

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Description of Dermatological Lesions

The clinical diagnosis rests on the essential elements of the basic skin lesions (where they are; how many there are; how they behave; etc)

Primary lesions – due to a direct expression of the disease process eg macules, papules, vesicles
Secondary lesions – follow the disease process eg ulcers, scare.

Types of lesions:
Macule – ‘spot’ – flat, circumscribed area of discolouration up to 1cm in diameter – not raised and no change to consistency of skin; differ from surrounding skin based on colour. eg freckle, flat moles, port-wine stains, measles, rubella. tattoos
Patch – macule larger than 1 cm in diameter; many consider the term ‘large macule’ more appropriate than ‘patch’; eg vitiligo
Papule – ‘pimple’ – raised solid, elevated, circumscribed area of up to 1cm in diameter. eg naevus, wart, insect bite, some acne lesions, psoriasis
Nodule – solid, palpable, circumscribed lesion elevated from the skin surface and larger than 1 cm in diameter; eg rheumatoid nodule, lipoma
Plaque – large disc shaped elevated lesion often formed by the coalescence of papules or nodules eg psoriasis, eczema
Vesicle – circumscribed elevation containing fluid – small blister – less than 0.5cm in diameter. eg herpes simplex, varicella, allergic contact dermatitis, sunburn
Bulla – large blister – greater than 0.5cm in diameter; eg bullous pemphigoid
Pustule – circumscribed, visible accumulation of cloudy exudate. eg acne, impetigo, folliculitis, pustular psoriasis if palms and soles
Wheal – firm area of dermal oedema, usually raised, white, compressive and accompanied by a surrounding red ‘flare’, usually due to allergic reaction (hives)
Crust – mass of dried exudate. “Scab”. eg impetigo.
Excoriation – scratch mark, eg from scratching, rubbing or picking
Scale – easily detached flake of stratum corneum eg psoriasis, superficial fungal infections, pityriasis rosea
Sclerosis – induration of the dermis or subcutaneous tissue to an increase in collagen production
Cicatrice – connective tissue replacement following loss of dermal tissue
Sinus – tract leading to the surface of the skin
Erosion – loss of epidermal structures; moist; circumscribed; usually depressed
Ulcer – loss of dermis and/or subcutaneous tissue

Shape:
Annular – round ring like distribution – the rim is different to the centre
Arciform/arcuate – crescent shape; incomplete circles
Circinate – annular lesions coalesce together – parts of individual circles form larger lesions
Conical – profile of lesion shows a cone like mass
Digitate – finger shaped
Geographic – lesion appears like the outline of a continent on a map
Imbricated – lesions have normal skin between abnormal zones
Linear – long thin lesions or distribution of a lesion along a thin line
Livedo – “chickenwire” criss-cross pattern
Nummular/discoid – coin size and coin shaped, made up of round flat discs
Oval – oval shaped
Pedunculate – attached to the skin via a stalk like structure
Petaloid – nummular/discoid lesions that have merged together
Punctate – punched out with well defined borders
Serpiginous – snake like
Stellate – star shaped
Target – multiple concentric rings

Borders:
Sharp – edge of lesion easily distinguished from normal skin
Diffuse – edge of lesion blends with normal skin

Arrangement:
Disseminated – spread over a large area in an even distribution
Grouped – lesions found in discrete groups
Confluent – lesions begin as separate entities but join together over a period of time

Specific clinical signs:
Auspitz sign – pinpoint bleeding when scale lesion is removed (eg psoriasis)
Koebner phenomenon – secondary skin lesion caused by physical trauma (eg psoriasis, eczema)
Nikolsky sign – detachment of epidermis due to lack of skin cohesion (eg blistering diseases)
Diascopy – use of a glass slide pressed against a lesion; dilated capillaries/erythema will blanch and haemorrhagic/purpuric lesions do not blanch

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