Skin examination: primary and secondary lesions !

Exam technique

How the skin is looked at and felt, and how its lesions are named so that any colleague understands what you saw.

Updated 2026-11-01

See it in 3D: Skin

What it is

The skin exam combines inspection in good light with palpation of the whole skin surface, hair, nails and visible mucosa. Its core is describing each lesion in a shared vocabulary: the primary lesion type (what appears first) and secondary changes (what evolution, scratching or infection leave behind). A precise description guides the differential diagnosis before any test and lets the lesion be followed over time.

Landmark anatomy

Epidermis: the surface layer; its changes produce scale, crust and colour change through the melanocytes of the basal layer.
Dermis: holds vessels, nerves and appendages; dermal oedema makes the wheal, dermal inflammation makes papules and plaques.
Hypodermis (subcutis): the fat where deep nodules such as erythema nodosum sit.
Fluid-filled lesions form by splitting within the epidermis or between epidermis and dermis; the level changes the look (flaccid or tense blister).

Technique, step by step

Explain the exam, ask permission and ensure privacy; use daylight or bright white light and uncover one region at a time.
Inspect in order, head to toe: scalp, face, trunk, limbs, skin folds, palms, soles, web spaces, nails and mucosa.
Note the overall colour: pallor, cyanosis, jaundice, erythema and hyperpigmentation (in dark skin, check conjunctivae, gums and palms).
Feel temperature with the back of the hand; texture, moisture and thickness with the fingertips.
Check turgor by gently pinching the skin below the clavicle or on the forearm and watching how fast it returns.
For each lesion, define the primary type, size measured with a ruler, colour, shape, border and surface.
Palpate the lesion: flat or raised, solid or fluid-filled, consistency, tenderness and whether it is fixed.
Press with a glass slide or a finger (diascopy): if it does not blanch, blood is outside the vessels (petechia, purpura).
Describe the distribution (localised, generalised, symmetric, sun-exposed, flexural) and arrangement (linear, annular, grouped, dermatomal).
Record it all in descriptive language and, when possible, a photo with a scale for comparison at follow-up.

Primary lesions: the basic vocabulary (the 1 cm cut-off is the most used; some texts use 0.5 cm)

Lesion	Definition	Example
Macule	Flat, non-palpable colour change under 1 cm	Freckle, petechia
Patch	Flat, non-palpable colour change over 1 cm	Vitiligo, café-au-lait spot
Papule	Solid, palpable elevation under 1 cm	Wart, insect bite
Plaque	Solid elevation with a broad surface, over 1 cm	Psoriasis
Nodule	Solid, deeper lesion (dermis or subcutis), over 1 cm	Lipoma, erythema nodosum
Vesicle	Elevation filled with clear fluid, under 1 cm	Chickenpox, herpes simplex
Bulla	Elevation filled with clear fluid, over 1 cm	Second-degree burn, pemphigoid
Pustule	Elevation containing pus (not always infected)	Acne, folliculitis
Wheal	Transient oedematous elevation, lasts under 24 hours	Urticaria
Cyst	Cavity with fluid or semisolid content, fluctuant to touch	Epidermoid cyst

Abnormal findings

Secondary lesions: scale (shedding stratum corneum), crust (dried serum or blood), erosion (partial epidermal loss, heals without a scar) and ulcer (reaches the dermis, scars).
Other secondary lesions: fissure (linear crack), excoriation (scratch injury), lichenification (skin thickened by chronic rubbing), atrophy and scar.
Non-blanching petechiae and purpura, especially with fever, point to a bleeding disorder or severe infection and are reported at once.
Grouped vesicles on a dermatome suggest herpes zoster; wheals that move within hours suggest urticaria.
Nursing angle: assess pressure-injury risk over bony prominences (sacrum, heels) and report any non-blanching redness.

Common errors

Using diagnoses instead of descriptions ('looks like eczema') rather than naming the primary lesion.
Examining in poor light or only the area the patient points to; many important lesions sit in hidden places (scalp, soles, between toes).
Forgetting that erythema and pallor look different in dark skin; compare with nearby normal skin and with mucosa.
Not measuring: 'large' or 'small' cannot be compared at follow-up.

Test yourself

Think of the answer, then tap the question to see it.

What is a raised, solid, 3 cm lesion with a flat scaly surface on the elbow called?

A plaque (solid raised lesion over 1 cm); with silvery scale on the elbow, psoriasis is the classic example.

What separates an erosion from an ulcer?

An erosion loses only part of the epidermis and heals without a scar; an ulcer reaches at least the dermis and scars.

What is diascopy for?

Pressing on the lesion: erythema blanches because the blood is inside vessels; petechiae and purpura do not, because the blood has left the vessels.

How long does each urticarial wheal typically last?

Under 24 hours; one lesion fades while another appears somewhere else.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

Skin

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Terminology in dermatology (DermNet, 2026); Description of Skin Lesions - Dermatology - Merck Manual Professional Edition (Merck Manuals, 2026); 21.1 Structure and Functions of the Skin - Clinical Nursing Skills | OpenStax (OpenStax, 2024).

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Representative model, for educational purposes only.