Why Skin Lesion Examination Is a High-Yield OSCE Skill
Dermatology accounts for over 15% of GP consultations in the UK, yet it is often under-taught in medical school. OSCE skin stations typically test two things: your ability to systematically describe any skin lesion using accurate dermatological terminology, and your recognition of features that require urgent referral. You do not need to be a dermatologist — you need a reliable, reproducible description framework.
Setup
- Wash hands, introduce, gain consent, ensure adequate lighting
- Ask about pain, itch, or bleeding before touching
- Use a ruler for size (always state in centimetres — two dimensions)
- Examine the index lesion AND the rest of the skin (distribution is a major diagnostic clue)
- Examine regional lymph nodes
Primary and Secondary Lesion Terminology
First identify whether the lesion is primary (arose from previously normal skin) or secondary (a change to a pre-existing lesion).
Primary Lesions
| Term | Definition | Example |
|---|---|---|
| Macule | Flat, non-palpable colour change, under 1 cm | Freckle, purpura, vitiligo |
| Patch | Flat, non-palpable colour change, over 1 cm | Café-au-lait, port wine stain |
| Papule | Raised, solid, palpable, under 1 cm | Wart, sebaceous cyst, acne |
| Plaque | Raised, solid, flat-topped, over 1 cm | Psoriasis, eczema |
| Nodule | Raised, solid, over 1 cm, extends into dermis | Dermatofibroma, melanoma |
| Vesicle | Fluid-filled blister, under 1 cm | Herpes simplex, chickenpox |
| Bulla | Fluid-filled blister, over 1 cm | Bullous pemphigoid, impetigo |
| Pustule | Pus-filled lesion | Acne, folliculitis |
| Wheal | Transient raised erythematous lesion | Urticaria |
Secondary Lesions
Scale (psoriasis), crust (impetigo), erosion (loss of epidermis, heals without scar), ulcer (full-thickness skin loss, may scar), excoriation (scratch marks), lichenification (thickened skin from chronic scratching), scar, atrophy.
Systematic Description: SSSCCERD
🧠 Mnemonic
SSSCCERD — describe every lesion in this order
S — Site: anatomical location and which part of the body
S — Size: length x width in centimetres (use a ruler)
S — Shape: round, oval, irregular, annular, serpiginous, linear
C — Colour: uniform or variable? Brown, black, pink, red, white, blue, hypopigmented?
C — Consistency and surface: smooth, rough, verrucous, scaly, crusted; firm or soft to palpation?
E — Edge: well-defined or poorly defined? Regular or irregular border? Rolled?
R — Relationship to surrounding skin: erythema, satellite lesions, telangiectasia, pigmentation
D — Distribution: solitary or multiple? Dermatomal, flexural, extensor, sun-exposed, symmetrical?
ABCDE of Malignant Melanoma
🧠 Mnemonic
ABCDE — features of malignant melanoma
A — Asymmetry: one half does not mirror the other
B — Border: irregular, ragged, notched, or blurred edges
C — Colour: variation within the lesion — brown, black, red, white, blue
D — Diameter: greater than 6 mm (though early melanomas may be smaller)
E — Evolution: any change in size, shape, colour; new symptoms — bleeding, itch, crusting
⚠️ Red Flag
Any pigmented lesion with three or more ABCDE features, or any lesion that is new, changing, or bleeding, warrants an urgent 2-week-wait referral to dermatology. Never reassure a patient about a changing pigmented lesion without senior review first.
Common OSCE Skin Findings
| Condition | Key features to describe |
|---|---|
| Basal cell carcinoma | Pearly nodule with rolled telangiectatic border, possible central ulcer; slow-growing; sun-exposed areas |
| Squamous cell carcinoma | Keratotic, crusted plaque or nodule; may ulcerate; can metastasise (unlike BCC) |
| Seborrhoeic keratosis | Stuck-on, warty, brown/black waxy surface — press with pen: feels greasy; benign |
| Dermatofibroma | Firm papule, dimples inward on pinching (Fitzpatrick sign); typically lower limb |
| Psoriasis plaque | Erythematous plaque with silvery scale; extensor surfaces; Auspitz sign (pinpoint bleeding on removing scale) |
| Lichen planus | Polygonal, Purple, Pruritic, Planar Papules (4 Ps); Wickham's striae on surface; flexor surfaces and oral mucosa |
Distribution Patterns as Diagnostic Clues
| Distribution | Think of |
|---|---|
| Flexural (antecubital fossa, popliteal fossa) | Atopic eczema |
| Extensor surfaces | Psoriasis, dermatitis herpetiformis |
| Dermatomal (following one nerve) | Herpes zoster (shingles) |
| Sun-exposed areas (face, V of chest, dorsal hands) | Lupus, polymorphic light eruption, actinic keratosis |
| Symmetrical flexures | Contact dermatitis, intertrigo |
How to Present
"On examination, there is a single [primary lesion type] on the [anatomical site]. It measures [X] by [Y] cm and is [shape]. The colour is [uniform/variable — describe colours]. The border is [regular/irregular, well/poorly defined]. The surface is [smooth/scaly/crusted]. There are [no/satellite lesions/telangiectasia]. Palpation reveals it is [firm/soft/fixed/mobile]. Examination of the rest of the skin shows [clear/similar lesions]. Regional lymph nodes are [not enlarged/enlarged]. My differential is [diagnosis]. Given [specific features], I would [refer urgently/monitor/reassure]."
Frequently Asked Questions
"How do I describe a skin lesion systematically in an OSCE?"
Use the SSSCCERD framework: Site, Size (in cm), Shape, Colour, Consistency and surface, Edge, Relationship to surrounding skin, and Distribution. Always examine the rest of the skin, mucous membranes (nails, scalp), and regional lymph nodes rather than focusing solely on the index lesion.
"What is the difference between a macule and a papule?"
A macule is flat and non-palpable — a colour change only, under 1 cm. A papule is raised and palpable — a solid elevation of the skin, also under 1 cm. Over 1 cm: a patch is the large equivalent of a macule; a plaque is the large equivalent of a papule with a flat top.
"What features of a skin lesion would make you refer urgently?"
Urgent 2-week-wait referral is indicated for any pigmented lesion with ABCDE features (Asymmetry, irregular Border, Colour variation, Diameter over 6 mm, Evolution), any non-healing ulcer, any rapidly growing lesion, or any lesion on the lip or ear (higher SCC metastatic risk). New nodules, unexplained thickening, or lesions in immunosuppressed patients also warrant urgent review.
"What is the difference between BCC and SCC?"
Basal cell carcinoma typically presents with a pearly nodule with a rolled, telangiectatic border on sun-exposed skin, growing slowly and invading locally but rarely metastasising. Squamous cell carcinoma presents as a keratotic, crusted plaque or nodule that may ulcerate and can metastasise — particularly in immunosuppressed patients or when on the lip, ear, or genitalia.
"What does the distribution of a rash tell you diagnostically?"
Distribution is one of the most powerful diagnostic clues. Flexural rashes suggest atopic eczema. Extensor rashes suggest psoriasis. A dermatomal distribution following a single dermatome suggests herpes zoster. Photo-distributed rashes (face, V of chest, forearms) suggest lupus or polymorphic light eruption. Symmetrical peripheral distribution suggests contact dermatitis or a systemic drug reaction.
Related guides: [Breast Examination OSCE](/blog/breast-examination-osce) · [Thyroid Examination OSCE](/blog/thyroid-examination-osce) · [How to Pass Your OSCE](/blog/how-to-pass-your-osce)