Pigmented Skin Lesion OSCE Examination

Contents

1. Introduction
2. General Inspection
3. Close Inspection of the Lesion
4. Palpation
5. Dermatoscopy
6. Regional Lymph Node Examination
7. Completing the Examination
8. Quiz

Introduction

Wash your hands and don personal protective equipment if appropriate.

Introduce yourself to the patient and ensure to mention your grade e.g. 3rd year medical student/junior doctor/consultant.

Confirm the patient's details taking 3 points of identification usually; full name, date of birth and NHS/hospital number.

Obtain consent for the examination, ensuring to explain what the examination will entail. Dermatological examination often involves close inspection of the skin and may require the patient to undress, so a clear explanation and a chaperone are particularly important.

Expose the patient appropriately. Although you will focus on the lesion of concern, malignant skin lesions can be multiple and can arise anywhere, so be prepared to inspect a wide area of skin in good lighting. Ensure the patient is positioned comfortably and that privacy is maintained.

Ask the patient if they have any pain or tenderness before you begin, and ask whether the lesion itches, bleeds or has changed, as these are important parts of the history that guide your examination.

General Inspection

Begin with a general inspection of the patient from the end of the couch. Note whether they appear well or unwell, and look for clues that may relate to skin cancer risk, such as evidence of chronic sun exposure (weathered, wrinkled skin and multiple solar lentigines), fair skin, red or blond hair and numerous moles. These features are all associated with an increased risk of melanoma.

Scan the visible skin for the overall number, distribution and variety of pigmented lesions. A patient with many naevi that all look broadly similar is reassuring; a single lesion that stands out as different from all the others is described as the 'ugly duckling' sign and warrants close attention, as melanomas frequently look unlike a patient's other moles.

The pattern of distribution is itself informative. Lesions concentrated on sun-exposed (photodamaged) sites such as the face, ears, forearms and lower legs reflect cumulative ultraviolet damage and are more likely to harbour the worrying lesions of later life. Lesions on acral skin (palms, soles and digits) deserve particular care because melanoma here is easily overlooked, while lesions over the trunk in younger people are the more typical sites for new naevi. Noting where the lesions sit helps you weigh the likelihood of malignancy.

It is also worth noting the patient's skin phototype. Individuals with Fitzpatrick type I or II skin, who burn easily and tan poorly, accumulate more ultraviolet-induced DNA damage and are at substantially higher risk of melanoma and non-melanoma skin cancer than those with darker skin.

Look around the bedside for relevant objects such as a wide-brimmed hat, sun cream, dressings over a biopsy site, or a dermatoscope, which may give clues to the clinical context. Note any obvious scars from previous skin surgery, which may suggest a history of skin cancer, and any signs of immunosuppression (for example a transplant patient), as immunosuppressed individuals are at markedly increased risk of skin malignancy.

Close Inspection of the Lesion

Move to a close inspection of the lesion of concern. Examine it in good lighting and, where available, with magnification. First record the site and the number of lesions, then describe the lesion systematically. A widely used framework is site, size, shape, colour, morphology and margin, which ensures nothing is omitted.

• Site – document the anatomical location precisely. Some sites carry particular significance; for example, melanomas on the sole, palm or under a nail (acral lentiginous melanoma) are easily missed and are the most common subtype in people with darker skin. A pigmented band running the length of a nail that extends onto the surrounding skin fold (Hutchinson's sign) raises concern for subungual melanoma and should never be dismissed as a bruise.
• Size – measure the lesion in millimetres rather than estimating. A diameter greater than 6 mm is one of the recognised warning features for melanoma, although small melanomas certainly occur.
• Shape – note whether the lesion is round, oval or irregular. Asymmetry, where one half does not mirror the other, is a concerning feature, as benign naevi tend to be symmetrical.
• Colour – benign moles are usually a uniform shade of brown. Variation in colour within a single lesion – combinations of brown, black, blue, red, white or grey – reflects melanocytes proliferating at different depths and is highly suggestive of melanoma.
• Morphology – describe whether the lesion is a macule (flat), a papule or nodule (raised), or a plaque. Be aware that elevation alone is not a reliable guide: most early melanomas are flat (superficial spreading type) and most raised pigmented papules are benign moles. It is a new nodular or ulcerated component that is worrying, as nodular melanoma can grow vertically and metastasise early.
• Margin – benign lesions tend to have a well-defined, regular border. An irregular, notched or poorly defined border suggests uncontrolled growth of malignant cells into surrounding skin.

Try to decide whether the lesion is truly pigmented (melanocytic) or simply thickened, keratotic skin, because several benign lesions can score falsely on these criteria. The classic mimic is the seborrhoeic keratosis, which has a 'stuck-on' appearance, a greasy or warty surface, and on closer inspection a brain-like (cerebriform) pattern with blackhead-like plugs and tiny pale keratin cysts; recognising these features should reassure you.

Conversely, a small minority of melanomas are amelanotic, appearing pink or skin-coloured with little or no pigment. These are easily mistaken for a benign lump or even a pyogenic granuloma, so any persistent, growing or bleeding nodule deserves the same suspicion even when it is not dark.

The most familiar tool for assessing a pigmented lesion is the ABCDE criteria, which formalises many of the features above:

• A – Asymmetry: the two halves of the lesion are not symmetrical.
• B – Border: the edge is irregular, blurred or notched.
• C – Colour: there are two or more colours within the lesion.
• D – Diameter: the lesion is greater than 6 mm across.
• E – Evolution: the lesion has changed in size, shape, colour or symptoms over time, or is new.

The E for evolution is arguably the single most important feature, because a lesion that is changing is far more concerning than one that has been stable for years. This is why taking a focused history alongside the examination is essential.

Image - The ABCD features contrasting melanoma (left of each pair) with a benign mole (right): asymmetry, irregular border, colour variation and a diameter greater than 6 mm

Public domain source by the National Cancer Institute [Public domain]

In UK primary care the weighted 7-point checklist is often used to decide whether to refer a lesion under the suspected cancer pathway. Major features (2 points each) are a change in size, an irregular shape and an irregular colour. Minor features (1 point each) are a diameter of 7 mm or more, inflammation, oozing or crusting and a change in sensation such as itch. A total score of 3 or more, or any single strongly concerning feature, prompts urgent referral to dermatology.

Image - A malignant melanoma showing asymmetry, an irregular notched border and marked variation in colour within a single lesion

Public domain source by the National Cancer Institute [Public domain]

Palpation

Before touching the lesion, don gloves if there is any risk that it is infected or that you may be exposed to blood or other bodily fluids, for example if it is bleeding or crusted.

Gently palpate the lesion, comparing it to the surrounding normal skin. Assess the following:

• Surface texture – note whether the lesion feels smooth (as in a benign naevus) or rough and warty. A 'stuck-on', greasy, warty surface is characteristic of a benign seborrhoeic keratosis, a common mimic of melanoma in older patients.
• Elevation – determine whether the lesion is flat, raised or depressed. A new or growing raised nodule within a previously flat lesion is concerning.
• Crust – if a crust is present, note whether it lifts to reveal intact or ulcerated skin beneath, as a recurrent crust over a pigmented lesion may signal repeated minor bleeding.
• Temperature – compare the lesion with adjacent skin. Increased warmth points to inflammation or infection rather than a quiescent mole.
• Consistency – describe whether the lesion is soft, firm or hard. A hard, indurated lesion is more worrying than a soft one and may reflect dermal invasion.
• Fluctuance – gently press on opposite edges to test for a fluid-filled centre. Fluctuance suggests a cyst or abscess rather than a solid pigmented tumour.
• Mobility – assess how freely the lesion moves over the deeper tissues. A lesion that has become tethered or fixed to underlying structures is a worrying sign of invasion, whereas benign lesions usually move with the skin.
• Tenderness – note any pain on palpation, watching the patient's face. New tenderness in a previously asymptomatic lesion is a change worth documenting.

A useful 'soft' sign of benignity is the 'wobble sign': when a soft, fleshy lesion is gently moved from side to side it wobbles independently of the surrounding skin, which typically indicates a benign intradermal naevus rather than a firmly infiltrating tumour.

Take care to assess whether the lesion bleeds on gentle contact, as spontaneous bleeding or ulceration is a red-flag feature of malignancy. Ulceration reflects loss of the protective epidermis as the tumour outgrows its blood supply, and on histology it is an independent marker of poorer prognosis. Always palpate gently to avoid causing discomfort or trauma to a potentially fragile lesion.

Dermatoscopy

A dermatoscope is a handheld device combining magnification with a polarised light source. By reducing surface reflection it allows visualisation of pigment patterns and vascular structures beneath the stratum corneum that are invisible to the naked eye. Used by trained clinicians, dermatoscopy substantially improves the accuracy of distinguishing benign from malignant pigmented lesions.

In an OSCE you would offer to examine the lesion with a dermatoscope and describe the principle rather than necessarily perform a full analysis. Reassuring benign patterns include a symmetrical, regular pigment network, while features such as an atypical (irregular) network, blue-white veil, irregular streaks, dots and globules, and a regression structure raise suspicion of melanoma. Simple screening tools such as the three-point checklist (asymmetry, atypical network and blue-white structures) help non-experts decide which lesions to refer.

Image - A dermatoscope, which combines magnification with polarised light to reveal subsurface pigment and vascular patterns

Public domain source by Northerncedar [Public domain]

Regional Lymph Node Examination

If you identify a lesion that is suspicious for melanoma, you must examine the regional lymph nodes that drain the affected area. Melanoma classically spreads first via the lymphatics to the nearest nodal basin, so palpable lymphadenopathy in the relevant territory may indicate metastatic disease and significantly alters staging and prognosis.

Palpate the lymph node group that drains the site of the lesion, for example:

• The cervical nodes for lesions on the head, face and neck.
• The axillary nodes for lesions on the arm, upper trunk and breast.
• The inguinal nodes for lesions on the leg, lower trunk and perineum.

Note any nodes that are enlarged, hard, fixed or matted, as these features suggest malignant infiltration rather than reactive change. You should also feel along the line between the lesion and its draining nodes for any in-transit or satellite deposits, which are smaller skin or subcutaneous metastases lying along the lymphatic pathway.

The clinical nodal examination is only the bedside step. In a confirmed melanoma above a threshold Breslow thickness with no palpable nodes, the formal staging investigation of the nodal basin is a sentinel lymph node biopsy, which samples the first node draining the tumour to detect microscopic spread. Mentioning this in an OSCE shows you understand how the examination feeds into staging.

Image - The cervical nodal levels. Knowing the drainage territory of a lesion tells you which nodal basin to examine for spread

SimpleMed original

Completing the Examination

Thank the patient and ensure they are comfortable and re-dressed. Wash your hands.

Summarise your findings, describing the lesion using the site, size, shape, colour, morphology and margin framework and stating whether the ABCDE or 7-point checklist features raise concern.

To complete the examination, state that you would:

• Perform a full skin examination, checking the entire skin surface for any other suspicious lesions, as patients with one melanoma are at higher risk of a second primary.
• Examine the nails, scalp, hair, soles, palms and mucous membranes, as these less obvious sites can harbour melanomas that are easily overlooked.
• Take a focused history, including the duration and evolution of the lesion, symptoms such as itching or bleeding, sun exposure and sunburn, use of sunbeds, and any personal or family history of skin cancer.
• Document the lesion with clinical photography and accurate measurement to allow monitoring of change over time. A standard set comprises a locating image showing where the lesion sits on the body, a close-up macro image, and a dermatoscopic image.
• Take swabs or skin scrapings where infection is suspected, sending them for microbiology, virology or fungal culture as appropriate.
• Refer suspicious lesions urgently to dermatology under the suspected cancer (2-week-wait) pathway.
• Arrange definitive diagnosis by excision biopsy taking the whole lesion with a small (around 2 mm) clear margin, never a partial biopsy of a possible melanoma, and send the specimen for histology including Breslow thickness, the key prognostic measurement that guides any subsequent wide local excision.

Quiz

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