Section 09 of 09
Building your baseline library
You now have a framework for understanding what normal dermoscopic appearances look like — but reading about it is only the beginning. True pattern recognition comes from repeated observation.
The "hundred normals" principle
Many experienced dermoscopists recommend examining at least one hundred clearly benign lesions before you start trying to identify pathology. This is not a strict rule, but the principle is sound: the more normal you see, the better you become at recognising when something deviates from it.
In clinical practice, this means using your dermatoscope on every lesion you encounter — not only the ones that worry you. Examine the clearly benign moles, the obvious seborrhoeic keratoses, the small cherry angiomas. Each one adds to your mental library.
Practice strategies
Observe normal skin deliberately
When examining any patient, spend time looking at uninvolved skin. Note the baseline pattern, vessel visibility, and pigmentation.
Compare symmetric sites
The contralateral arm, leg, or nail provides an immediate normal reference. Asymmetry between sides can highlight abnormality — one of the simplest and most powerful techniques you have.
Sample multiple sites
During any skin examination, briefly observe face, trunk, extremities, and acral surfaces. Build familiarity with how normal varies across the body.
Note individual variation
What is normal for this person? Their background pigmentation, freckling pattern, and vessel visibility create their personal baseline.
Calibrate across phototypes
Deliberately observe patients across the phototype spectrum. The same anatomical site looks different in different individuals — and that difference is normal.
What to observe in each lesion
As you build your library, apply a consistent mental checklist for each lesion:
Check
Overall pattern
Does it have a recognisable structure (network, lacunae, comedo-like openings) or is it structureless?
Check
Symmetry
Is the pattern roughly symmetric across the lesion?
Check
Colour
How many colours are present? Are they uniform or varied?
Check
Borders
Are the edges well-defined or irregular?
Check
Site context
Does the appearance match what you would expect for this body site?
You are not trying to diagnose at this stage. You are simply training your eye to see systematically and to notice the qualities that make a lesion look organised and unremarkable.
What comes next
With this foundation of normal appearances, you are ready to learn what abnormal looks like. Module 3 — What is Abnormal — will introduce the dermoscopic features that suggest a lesion warrants further evaluation. You will find that many of these concerning features are simply the opposite of what you have learned here: an irregular network where you would expect a regular one, asymmetric colour where you would expect uniformity, chaotic structure where you would expect organisation.
That contrast — between the normal baseline you have built and the abnormal features to come — is exactly the foundation that makes dermoscopy work.
Which of the following approaches best support developing reliable dermoscopic pattern recognition?