01Purpose and principlesWhat the assessment is for and the core concepts behind it.
Polarised and non-polarised devices reveal partly different structures. Contact fluid reduces reflection for non-polarised examination, while polarisation can display deeper vessels and shiny white lines. Know the instrument used because apparent absence of a feature may reflect technique.
A two-step approach first asks whether a lesion is melanocytic and then whether its architecture is benign or suspicious. Algorithms support, rather than replace, clinical judgement. Lesions outside competence, nodular change and discordance between history and image should be referred or sampled appropriately.
Dermatoscopy principles should answer a defined clinical question and be integrated with history, examination and the consequences of error. Explain uncertainty, record the sampling or observation conditions, and arrange a result-review plan rather than treating an isolated finding as self-interpreting.
Key points
- Dermoscopy reduces surface reflection to reveal subsurface pigment and vascular structures that are not visible to the naked eye.
- Start with lesion identity, history and naked-eye morphology; dermoscopy refines probability but does not independently diagnose every lesion.
- Use a consistent algorithm within competence, looking for symmetry, colours, structures and melanoma-specific clues rather than one memorable sign.
- Clean contact equipment, avoid cross-contamination, and use non-contact technique over broken skin unless the device can be safely protected and decontaminated.
- For Dermatoscopy principles, describe what is seen before assigning a diagnosis, and record site, extent, symptoms, duration and change over time.
- A technically adequate result in Dermatoscopy principles can still be misleading when the wrong lesion, site, preparation or clinical question was selected.
02Indications, selection and cautionsWhen it is useful, when urgency changes and important limitations.
Assess symmetry of colour and structure across axes before focusing on a single local clue; chaotic distribution increases concern.
Pigment network, aggregated globules, streaks and homogeneous blue pigmentation can support melanocytic origin in the correct anatomical context.
Dotted, comma, hairpin, arborising or polymorphous vessels can refine differentials, but blanching pressure and contact fluid alter visibility.
A firm growing or bleeding nodule may lack classic melanoma structures and requires urgent assessment based on history and examination.
Face, palms, soles, nails and mucosa have specialised dermoscopic anatomy; general trunk rules cannot be transferred uncritically.
03Method and interpretationA systematic approach to the test and its findings.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Naked-eye lesion assessmentFirst step - Why
- Establish the clinical context before magnification.
- Interpretation and limitations
- Record duration, evolution, symptoms, size and morphology; dermoscopy cannot correct an incorrect site or incomplete history.
- 02
Polarised dermoscopy - Why
- Visualise pigment, vascular architecture and deeper reflective structures.
- Interpretation and limitations
- Inspect systematically and save an image only with consent; pressure may blanch vessels and immersion may obscure scale.
- 03
Baseline clinical photography - Why
- Support short-interval monitoring when specialist judgement selects surveillance.
- Interpretation and limitations
- NICE recommends baseline photography for an atypical melanocytic lesion not excised at first presentation in secondary or tertiary care, with review after three months.
- 04
Histopathological assessment - Why
- Resolve lesions selected for biopsy or excision.
- Interpretation and limitations
- Sampling must match the clinical question and suspected malignancy; a partial biopsy can miss the most diagnostic or deepest focus.
04Clinical next stepsHow the result changes management or prompts escalation.
01Planned assessmentUse dermatoscopic examination systematicallyFirst stepThe patient is stable and the result will alter diagnosis, referral or follow-up.+
- 1Define the question for Dermatoscopy principles, explain the process and obtain valid consent before exposing, touching, photographing or sampling skin.
- 2Choose representative anatomy, optimise lighting or specimen technique, and document site, morphology, symptoms and relevant previous treatment. Apply that step specifically within the dermatoscopy principles assessment and its recorded clinical context.
- 3Interpret the result beside the full clinical pattern, communicate uncertainty and arrange ownership of results and safety-netting. Apply that step specifically within the dermatoscopy principles assessment and its recorded clinical context.
02Uncertain resultResolve discordance in Dermatoscopy principlesThe technical finding conflicts with the history, lesion evolution or wider examination.+
- 1Recheck identity, site, timing, preparation, treatment exposure and whether the selected target was genuinely representative. Apply that step specifically within the dermatoscopy principles assessment and its recorded clinical context.
- 2Repeat or select a complementary test only when it can distinguish the remaining important alternatives. Apply that step specifically within the dermatoscopy principles assessment and its recorded clinical context.
- 3Seek dermatology, pathology, microbiology or allergy advice when clinicopathological disagreement would change urgent care. Apply that step specifically within the dermatoscopy principles assessment and its recorded clinical context.
03Urgent patternDo not let dermatoscopic examination delay escalationEscalationA rapidly progressive eruption, systemic illness, threatened vision or airway, or suspected aggressive malignancy is present. Apply that step specifically within the dermatoscopy principles assessment and its recorded clinical context.+
- 1Stabilise immediate physiological threats and obtain same-day senior or specialty assessment according to the dominant emergency. Apply that step specifically within the dermatoscopy principles assessment and its recorded clinical context.
- 2DefinitiveTake time-critical images or specimens only when doing so will not postpone resuscitation, antimicrobials or definitive referral. Apply that step specifically within the dermatoscopy principles assessment and its recorded clinical context.
- 3Record evolution and communicate the differential, outstanding results and explicit deterioration triggers during handover. Apply that step specifically within the dermatoscopy principles assessment and its recorded clinical context.
05Risks, monitoring and follow-upComplications, safety checks and further assessment.
- Record who will review the result arising from Dermatoscopy principles, the expected timescale and the action threshold before the patient leaves.
- Compare subsequent findings with the original site description, dimensions, symptoms and image or specimen identifiers for Dermatoscopy principles.
- Reassess earlier if rapid growth, bleeding, ulceration, fever, mucosal disease, eye symptoms or functional compromise develops. Apply that step specifically within the dermatoscopy principles assessment and its recorded clinical context.
- Document technical limitations and previous treatment that could alter sensitivity or specificity of dermatoscopic examination.
- Close the loop after specialist or laboratory review, including clinicopathological disagreement and any need for repeat sampling. Apply that step specifically within the dermatoscopy principles assessment and its recorded clinical context.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
Technique changes findings
Polarisation, contact pressure and fluid affect which white lines, vessels and superficial structures become visible.
Chaos precedes clues
An asymmetric lesion with disordered colour and structure deserves focused search for malignancy features and clinical correlation.
Pink lesions still matter
Amelanotic melanoma and other cancers may present mainly through vessels, ulceration and change rather than brown pigment.
Anatomy rewrites rules
Parallel-ridge concern on acral skin and facial pseudonetwork require site-specific competence before interpretation.
Monitoring is selective
Serial imaging is appropriate only when the surveillance decision itself is safe and a reliable recall system exists.
07Common pitfallsFrequent interpretation and management errors.
- 01
Calling a lesion benign because one reassuring dermoscopic feature is present despite documented rapid growth.
- 02
Pressing firmly enough to erase diagnostically useful vessels in a pink or amelanotic lesion.
- 03
Applying trunk-based pigment-network rules unchanged to face, nail, palm or sole anatomy.
- 04
Photographing without recording exact site and scale, making later comparison unreliable.
- 05
Using monitoring to postpone referral for a nodular, ulcerated or otherwise high-risk lesion.