Accurate description of skin conditions is fundamental to dermatological diagnosis and communication among healthcare professionals. Dermatologists assess lesions by their distribution, morphology, arrangement, number, size, colour, and involved sites, noting symmetry, shape, and pattern. Palpation reveals surface and deep characteristics, such as layer involvement, scale adherence, or crust contents. Special techniques like Wood’s light for pigment and infections, or dermoscopy for pigmented lesions, aid evaluation.
Structure of the Skin
The skin comprises three layers: the outer epidermis, middle dermis, and deep subcutaneous tissue (hypodermis). A basement membrane separates epidermis from dermis, facilitating communication.
- Epidermis: A ‘brick wall’ of keratinocytes producing keratin. Contains melanocytes (melanin for pigment), Langerhans cells (immune antigen presentation), and Merkel cells (sensory function). Subdivided into stratum basale (basal layer of proliferating cells), stratum spinosum (prickle cell layer with desmosomes for adhesion), stratum granulosum (granular layer with keratohyaline granules), and stratum corneum (horny layer of dead, keratinized cells that shed).
- Dermis: Connective tissue with collagen, elastin, fibroblasts, vessels, nerves, and appendages (sweat glands, hair follicles, sebaceous glands).
- Subcutaneous tissue: Fat and connective tissue insulating and cushioning.
Epidermal appendages include eccrine sweat glands, apocrine scent glands (axillae, groin), and pilosebaceous units.
Distribution
Distribution describes lesion scatter or spread. Lesions may be solitary or multiple, with patterns aiding diagnosis.
| Term | Description | Examples |
|---|---|---|
| Generalised | Widespread, often symmetrical | Drug eruptions, viral exanthems |
| Localised | Confined to one area | Contact dermatitis |
| Dermatomal | Follows nerve root (e.g., shingles) | Herpes zoster |
| Extensor | Outer limb surfaces | Psoriasis |
| Flexural/Intertriginous | Skin folds | Flexural psoriasis, candidiasis |
| Follicular | Arising from follicles | Folliculitis |
| Seborrhoeic | Scalp, ears, eyebrows, nasolabial folds, sternum, interscapular | Seborrhoeic dermatitis |
| Symmetrical | Mirrored left/right | Atopic dermatitis |
| Truncal | Trunk predominant | Pityriasis rosea |
| Unilateral | One side | Naevus |
Other patterns: acral (hands/feet), centrofacial (face centre), grouped (clusters), linear/striate (lines), palmoplantar (palms/soles), photo-aggravated (sun-exposed).
Configuration of Lesions
Configuration refers to lesion shape/outline, often grouped for diagnostic clues.
- Annular: Circular, ring-like (e.g., granuloma annulare).
- Arcuate: Partial ring, bow-like.
- Discoid/Nummular: Coin/disc-shaped (e.g., discoid eczema).
- Figurate: Geometric patterns (polycyclic, serpiginous).
- Gyrate: Whirling circle (e.g., erythema gyratum repens).
- Linear: Line-like (e.g., phytophotodermatitis).
- Reticulate: Net-like (e.g., livedo reticularis).
- Target: Concentric rings, iris-like (e.g., erythema multiforme).
Colour
Lesion colour provides diagnostic hints.
- Carotenaemia: Yellow/orange from beta-carotene excess.
- Erythema: Red from dilated vessels (blanching).
- Violaceous: Purple (e.g., lichen planus).
- Hyper pigmentation: Increased melanin (brown/black).
- Hypopigmentation: Reduced melanin; leucoderma (white).
- Purple (Purpura): Non-blanching extravascular blood.
- Xanthoderma: Yellow from lipids/xanthomas.
Morphology
Morphology classifies primary lesions by type and size.
| Lesion Type | Size | Description |
|---|---|---|
| Macule/Patch | <1cm / >1cm | Flat, circumscribed colour change, non-palpable |
| Papule/Plaque | <1cm / >1cm | Palpable elevation, solid |
| Nodule/Tumour | >1cm | Deeper, larger solid elevation |
| Vesicle/Bulla | <1cm / >1cm | Fluid-filled, clear |
| Pustule | Varies | Pus-filled |
| Wheal | Varies | Oedematous, transient (urticaria) |
Shape terms: acuminate (pointed), dome-shaped, filiform, flat-topped, oval/round, pedunculated (stalked), sessile, umbilicated (central dip), verrucous (wart-like).
Skin Surface
Surface features describe texture.
- Crust: Dried exudate/serum.
- Scale: Flaky keratin; types: desquamation (shedding), psoriasiform (large white/silver), pityriasiform (branny), lichenoid (adherent), keratotic (horny), exfoliation (peeling), maceration (moist peel), verrucous (warty).
- Other: Follicular plugging, hyperkeratosis.
Secondary Changes
Lesions evolve with secondary features.
- Erosion: Superficial epidermal loss, moist, re-epithelialises.
- Excoriation: Scratch mark.
- Fissure: Linear epidermal crack to dermis.
- Lichenification: Thickened, leathery from rubbing.
- Scar: Fibrous replacement post-injury.
Nails
Nail terminology includes onycholysis (nail-plate separation), onychomadesis (shedding), pachyonychia (thickening), Beau’s lines (transverse grooves from insult), splinter haemorrhages.
Mucocutaneous Membranes
Mucosal changes mirror skin but use terms like aphthae (ulcers), Koplik spots (measles).
Miscellaneous Terms
- Alopecia: Hair loss (scarring/non-scarring).
- Atrophy: Thinning.
- Comedo: Blackhead/whitehead.
- Induration: Hardening.
Frequently Asked Questions (FAQs)
What is a primary skin lesion?
Primary lesions are initial changes: macules, papules, vesicles, etc., unaltered by trauma.
How does distribution aid diagnosis?
Patterns like dermatomal (shingles) or flexural (candidiasis) narrow differentials.
What causes colour changes in skin?
Erythema (vascular), pigmentation (melanin), purpura (blood).
What are secondary skin changes?
Erosions, lichenification from evolution/scratching.
Why use standardised terminology?
Ensures precise communication; aligns with ICD-11, SNOMED.
Consult DermNet’s full glossary or A-Z index for more.
References
- Terminology in dermatology — DermNet NZ (Author: Dr Amanda Oakley). 1997 (Updated). https://dermnetnz.org/topics/terminology
- Glossary of dermatopathological terms — DermNet NZ (Author: Dr Anthony Yung). 2007 (Updated 2016). https://dermnetnz.org/topics/dermatopathological-terminology
- Dermatology Terminology Guide — Scribd (Based on DermNet). N/A. https://ro.scribd.com/document/228684202/Terminology-in-Dermatology
- Dermatological Descriptive Terms — Patient.info. Recent access 2026. https://patient.info/doctor/dermatology/dermatological-descriptive-terms
- Glossary — DermNet NZ. Ongoing. https://dermnetnz.org/glossary
