Rash & Non-Pigmented Skin Lesion Examination – OSCE Guide

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This guide provides a clear step-by-step approach to examining a rash or non-pigmented skin lesion in an OSCE setting.

A rash is a general term usually used to describe a widespread eruption of skin lesions. A skin lesion is an area of abnormal skin.

This guide will discuss the examination of non-pigmented lesions, for pigmented lesions see the Geeky Medics guide to examining a pigmented skin lesion.


Wash your hands and don PPE if appropriate.

Introduce yourself to the patient including your name and role.

Confirm the patient’s name and date of birth.

Briefly explain what the examination will involve using patient-friendly language.

Explain the need for a chaperone if the skin lesion is located in an intimate area: “One of the ward staff members will be present throughout the examination, acting as a chaperone, would that be ok?”

Gain consent to proceed with the examination.

Adequately expose the skin lesion and position the patient so that you can clearly visualise it.

Ask the patient if they have any pain before proceeding with the clinical examination.

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General inspection

Skin lesions

Note the number, location and distribution of the patient’s skin lesions from the end of the bed:

  • Acral distribution: distal areas including the hands and feet (e.g. hand, foot and mouth disease).
  • Extensor distribution: extensor surfaces including the elbows and knees (e.g. psoriasis).
  • Flexural distribution: flexural surfaces including the axillae, genital region and cubital fossae (e.g. eczema).
  • Follicular distribution: affecting areas with increased numbers of sebaceous glands such as the face, chest and axillae (e.g. acne).
  • Dermatomal distribution: the skin lesions appear confined to one or several dermatomes and do not cross the midline (e.g. herpes zoster).
  • Seborrhoeic distribution: present in areas where there is an increased density of sebaceous glands such as the face and scalp (e.g. seborrhoeic dermatitis).

Objects and equipment

Look for objects or equipment on or around the patient that may provide useful insights into their medical history and current clinical status:

  • Medical equipment: may include bandages/dressings, oral medications and topical medications.
  • Mobility aids: items such as wheelchairs and walking aids give an indication of the patient’s current mobility status.
  • Prescriptions: prescribing charts or personal prescriptions can provide useful information about the patient’s recent medications.
  • Hand, foot and mouth disease
    Hand, foot and mouth disease 1

Close inspection

Size of the lesion(s)

Assess the size of the lesion(s): measure their width and height (if raised).

Configuration of the lesion(s)

Assess the configuration of the lesion(s).

Configuration refers to the shape or outline of skin lesions. The pattern of multiple lesions or the shape of an individual lesion can be useful in narrowing the differential diagnosis.

When assessing configuration, note the following characteristics:

  • Note if the lesion(s) is/are discrete or confluent.
  • Note the shape of the lesion(s).
  • Assess the border of the lesion(s) (e.g. well/poorly defined).
Configuration examples

Discrete lesions: individual lesions, clearly separated from one another (e.g. normal mole).

Confluent lesions: lesions that appear to be merging together (e.g. urticaria).

Linear lesions: lesions in the shape of a line (e.g. excoriations).

Discoid lesions: coin-shaped lesions (e.g. discoid eczema, discoid lupus).

Target lesions: concentric rings of varying colour, resembling a bullseye (e.g. erythema multiforme).

Annular lesions: ring-like lesions (e.g. tinea corporis).

  • Normal mole
    Normal mole

Colour of the lesion(s)

Assess the colour of the lesion(s).

Colour examples

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.

  • Petechiae
    Petechiae 9

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 lesions

Primary skin lesions are those which develop as a direct result of a disease process.

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).

  • Psoriasis
    Psoriasis 2

Secondary lesions

Secondary lesions are modifications of primary lesions that occur due to trauma to, or evolution of, the primary lesion.

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 have 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, intra-abdominal malignancy, Cushing’s syndrome, obesity, pregnancy). They undergo an evolution of colour from purple to pink to white as they mature.

  • Eczema
Assessment of a pigmented lesion

This guide does not cover the assessment of pigmented skin lesions, as they require a slightly different approach including screening for features suggestive of malignant melanoma using the ABCDE criteria

  • Asymmetry
  • Border irregularity
  • Colour variation or changes
  • Diameter
  • Elevation/evolution

For more information, see the Geeky Medics OSCE guide to examining a pigmented lesion.


Don gloves if there is a risk that the skin lesion is infective and/or is likely to expose you to bodily fluids (e.g. blood/pus).

Assess the surface characteristics 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 can 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 deeper characteristics 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.

Systemic examination

Some skin conditions have extracutaneous manifestations whilst other skin lesions may develop secondary to a systemic disease process. As a result, it’s important to perform a comprehensive assessment 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 psoriasis plaques, xanthomas (hyperlipidaemia) or rheumatoid nodules (rheumatoid arthritis).

Hair and scalp

Inspect the hair and scalp for relevant clinical signs.

Hair loss

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.

Hypertrichosis: non-androgen-dependent excess hair growth.


Scalp psoriasis: plaques of psoriasis located on the scalp, often resulting in visible scale in the hair.

Seborrhoeic dermatitis: often causes diffuse scale to be present throughout the scalp.

Mucous membranes

Inspect the oral mucosa for relevant clinical signs.

Hyperpigmented macules: pathognomonic for Peutz-Jeghers syndrome,  an autosomal dominant genetic disorder that results in the development of polyps in the gastrointestinal tract.

Bullae: associated with bullous pemphigoid, and pemphigus vulgaris, both autoimmune blistering disorders.

Whickham’s striae: a sign of lichen planus and can be in the buccal mucosa, but also on the genital skin.

  • Nail pitting
    Nail pitting 23

To complete the examination…

Explain to the patient that the examination is now finished and provide them with privacy to get dressed if relevant.

Thank the patient for their time.

Dispose of PPE appropriately and wash your hands.

Summarise your findings.

Further assessments and investigations

Suggest further assessments and investigations to the examiner:

  • Perform relevant examinations of any systems that may be related to dermatological findings (e.g. local lymph node assessment).
  • Swabs/skin scrapings of lesions: for microbiology, virology and fungal culture.
  • Dermatoscopy of lesions: to more accurately assess a skin lesion (particularly melanocytic or vascular lesions).
  • Perform a biopsy of the skin lesion: for histological analysis.


Text references

  1. British Association of Dermatologists. Handbook for Medical Students and Junior Doctors. Published in 2014. 
  2. Dermnet New Zealand. Dermatology terminology. Published in 1997.  Revised in 2017.
  3. NICE Clinical Knowledge Summaries. Melanoma and pigmented lesions. Revised March 2011.

Image references

  1. Ngufra. Adapted by Geeky Medics. Hand, foot and mouth disease. Licence: CC BY-SA
  2. MediaJet. Adapted by Geeky Medics. Psoriasis. Licence: CC BY-SA
  3. Roshu Bangal. Adapted by Geeky Medics. Acne. Licence: CC BY-SA.
  4. Fisle. Adapted by Geeky Medics. Herpes zoster. Licence: CC BY-SA.
  5. Roymishali. Adapted by Geeky Medics. Seborrhoeic dermatitis. Licence: CC BY-SA
  6. Allergy research. Adapted by Geeky Medics. Urticaria. Licence: CC BY
  7. Masryyy. Adapted by Geeky Medics. Discoid eczema. Licence: CC BY
  8. James Heilman, MD. Adapted by Geeky Medics. Erythema multiforme. Licence: CC BY-SA
  9. Hektor. Adapted by Geeky Medics. Purpura. Licence: CC BY-SA
  10. James Heilman, MD. Adapted by Geeky Medics. Linea nigra. Licence: CC BY-SA
  11. James Heilman, MD. Adapted by Geeky Medics. Vitiligo. Licence: CC BY-SA
  12. Grook Da Oger. Adapted by Geeky Medics. Pityriasis versicolour. Licence: CC BY-SA.
  13. Jmarchn. Adapted by Geeky Medics. Keratocanthoma. Licence: CC BY-SA
  14. Mohammad2018. Adapted by Geeky Medics. Bullous pemphigoid. Licence: CC BY-SA
  15. El Pantera. Adapted by Geeky Medics. Furuncle. Licence: CC BY-SA
  16. Drvgaikwad. Adapted by Geeky Medics. Carbuncle. Licence: CC BY.
  17. Svdmolen. Adapted by Geeky Medics. Scar. Licence: CC BY-SA
  18. Htirgan. Adapted by Geeky Medics. Keloid scar. Licence: CC BY-SA
  19. Milorad Dimić M.D. Adapted by Geeky Medics. Venous ulcer. Licence: CC BY 3.0
  20. Jonathan Moore. Adapted by Geeky Medics. Arterial ulcer. Licence: CC BY 3.0
  21. PanaromicTiger. Adapted by Geeky Medics. Striae. Licence: CC BY-SA
  22. Делфина. Adapted by Geeky Medics. Seborrhoeic keratosis. Licence: CC BY-SA
  23. Seenms. Adapted by Geeky Medics. Nail pitting. Licence: CC BY-SA
  24. CopperKettle. Adapted by Geeky Medics. Onycholysis. Licence: CC BY-SA
  25. Adapted by Geeky Medics. CHeitz. Koilonychia. Licence: CC BY 2.0
  26. Thirunavukkarasye-Raveendran. Adapted by Geeky Medics. Alopecia areata. Licence: CC BY
  27. Adapted by Geeky Medics. Abdullah Sarhan. Peutz-Jager syndrome. Licence: CC BY-SA
  28. Oladokun R et al. Atlas of Paediatric HIV infection. Adapted by Geeky Medics. Licence: CC BY-SA.
  29. Grook da oger. Adapted by Geeky Medics. Licence: CC BY-SA 4.0.
  30. Medicalpal. Adapted by Geeky Medics. Licence: CC BY-SA 4.0.


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