Erythematous lesions: redness of the skin caused by an increased blood supply to the area. Erythematous lesions will blanch when pressure is applied.
Purpuric lesions: reddish/purple discolouration of the skin caused by small blood vessels bleeding into the skin. Purpuric lesions do not blanch when pressure is applied. Petechiae are small purpuric lesions less than 2mm in diameter whereas ecchymoses are larger purpura more than 2mm across (commonly referred to as a bruise).
Hyperpigmented lesions: areas of darker skin caused by excess melanin production. Hyperpigmentation may be diffuse (e.g. Addison’s disease) or discrete (linea nigra in pregnancy).
Hypopigmented skin lesions: areas of paler skin caused by melanocyte and melanin depletion or dysfunction. Pityriasis versicolour is a superficial fungal infection of the skin that impairs melanocyte function resulting in hypopigmented skin lesions.
Depigmentation: areas of skin which appear completely white due to the absence of melanin. Vitiligo is an autoimmune condition that results in the destruction of melanocytes and loss of pigment in the areas of skin affected.
Linea nigra 10
Pityriasis versicolour 12
Morphology of the lesion(s)
Assess the form and structure of the lesion(s): note if individual lesions appear flat, raised above the plane of the skin or depressed below it.
Primary skin lesions are those which develop as a direct result of a diseaseprocess.
Macule: a flat area of altered colour less than 1.5cm in diameter.
Patch: a flat area of altered colour greater than 1.5cm in diameter.
Papule: a solid raised palpable lesion less than 0.5cm in diameter.
Nodule: a solid raised palpable lesion greater than 0.5cm in diameter.
Plaque: a palpable flat lesion usually greater than 1cm in diameter. Most plaques are raised, however, some may be thickened without being visibly raised.
Vesicle: a raised, clear fluid-filled lesion less than 0.5cm in diameter.
Bulla: a raised, clear fluid-filled lesion greater than 0.5cm in diameter.
Pustule: a pus-containing lesion less than 0.5cm in diameter.
Abscess: a localised accumulation of pus.
Wheal: an oedematous papule or plaque caused by dermal oedema.
Boil/furuncle: staphylococcal infection around or within a hair follicle.
Carbuncle: staphylococcal infection of adjacent hair follicles (i.e. multiple boils/furuncles).
Herpes zoster 4
Secondary lesions are modifications of primarylesions that occur due to trauma to, or evolution of, the primarylesion.
Excoriation: loss of epidermis associated with trauma.
Lichenification: thickening of the epidermis with exaggeration of normal skin lines, typically caused by chronic rubbing or scratching of an area (e.g. chronic eczema).
Scales: visible fragments of the stratum corneum as it is shed from the skin, most commonly associated with psoriasis.
Crust: a rough surface consisting of dried serum, blood, bacteria and cellular debris. The serum, blood, bacteria and debris has usually exuded through an eroded epidermis.
Scar: new fibrous tissue which occurs after skin injury. Atrophic scarring involves the thinning of normal tissues underlying the scar resulting in a cratering effect. Hypertrophic scarring involves the hyperproliferation of scar tissue within the wound boundary, resulting in a prominent scar. Keloidal scarring involves the hyperproliferation of scar tissue beyond the wound boundary resulting in a scar that is significantly larger than the original skin insult.
Ulcer: a localised defect in the skin of irregular size and shape where the epidermis and some dermis have been lost. Ulcers ultimately result in scarring when healed.
Fissure: a sharply-defined, linear or wedge-shaped tear in the epidermis with abrupt walls, typically due to excess skin dryness.
Striae (stretch marks): purple lines on the skin caused by tearing during the rapid growth or overstretching of skin (e.g. growth spurts, ascites, intrabdominal malignancy, Cushing’s syndrome, obesity, pregnancy). They undergo an evolution of colour from purple to pink to white as they mature.
Normal scar 17
Keloid scar 18
Venous leg ulcer 19
Arterial leg ulcer 20
Assessment of a pigmented lesion
To perform a structuredassessment of a pigmentedlesion you should apply the ABCDE approach.³
Assess the symmetry of the skinlesion: asymmetry is suggestive of malignancy.
Assess the borders of the skinlesion: note if they appear well-defined. Poorly defined borders are suggestive of malignancy.
Colour variation or changes
Assess the colour of the skinlesion: note if the colour appears consistent throughout the lesion. The presence of multiple colours within a single skin lesion is suggestive of malignancy.
Assess the diameter of the skinlesion: measure the size of the skin lesion and ask the patient if it has been growing in size. Progressively enlarging skin lesions, particularly those over 6mm in diameter are suggestive of malignancy.
Assess the elevation of the skinlesion and take a history of the lesion’sevolution: elevated skin lesions and those which have a history of bleeding and itching are more concerning for malignancy.
If you identify a skinlesion which may be malignant you should perform a comprehensive assessment for other suspicious lesions and examine the regional lymph nodes.
Seborrhoeic keratosis 22
Don gloves if there is a risk that the skin lesion is infective and/or is likely to expose you to bodilyfluids (e.g. blood/pus).
Assess the surfacecharacteristics of the lesion:
Texture: note if the lesion feels smooth (e.g. ecchymoses) or rough (e.g. psoriatic plaque).
Elevation: note if the lesion is flat (e.g. ecchymoses), raised (e.g. keratoacanthoma) or depressed (e.g. hypotrophic scar).
Crust: if present, assess if you are able to remove the crust and inspect the underlying tissue (e.g. psoriasis).
Temperature: assess the temperature of the lesions (e.g. an abscess may feel warm).
Assess the deepercharacteristics of the lesion:
Consistency: note if the lesion feels hard, firm or soft.
Fluctuance: hold the lesion by its sides and then apply pressure to the centre of the mass with another finger. If the lesion is fluid-filled (e.g. cyst) then you should feel the sides bulging outwards.
Mobility: assess if the lesion feels mobile or is tethered to other local structures.
Tenderness: may indicate infective and/or inflammatory aetiology.
Some skinconditions have extracutaneous manifestations whilst other skinlesions may develop secondary to a systemic disease process. As a result, it’s important to perform a comprehensiveassessment to identify relevant pathology.
Hands and elbows
Inspect the nails and hands for relevant clinical signs.
Nail pitting: punctate depressions of the nail plate associated with eczema, psoriasis and alopecia areata.
Onycholysis: separation of the distal end of the nail plate from the nail bed associated with psoriasis and fungal nail infection.
Koilonychia: spoon-shaped nails, associated with iron deficiency anaemia (e.g. malabsorption in Crohn’s disease).
Inspect the elbows for evidence of psoriasisplaques, xanthomas (hyperlipidaemia) or rheumatoidnodules (rheumatoid arthritis).
Hair and scalp
Inspect the hair and scalp for relevantclinicalsigns.
Alopecia areata: well-defined patches of hair loss with surrounding normal hair.
Alopecia totalis: loss of all hair from the scalp.
Excess hair growth
Hirsutism: androgen-dependent excess hair growth in females.