How anatomical site changes the picture

One of the most important lessons in dermoscopy is that "normal" looks different depending on where you are looking. A perfectly healthy lesion on the back will have a very different dermoscopic appearance from a perfectly healthy lesion on the sole of the foot. If you only learn one version of normal, you will be confused — or falsely alarmed — when you examine other body sites.

Face

The face has a thinner epidermis, abundant sebaceous glands, and has accumulated years of sun exposure in most adults. The classic pigment network is replaced by a pattern called pseudonetwork — which looks similar to a pigment network at first glance, but the lighter holes within it are actually the openings of hair follicles and sebaceous glands, not dermal papillae.

This distinction matters because an inexperienced observer might see a facial pseudonetwork and incorrectly interpret it as an atypical pigment network. Understanding that the face has its own version of normal prevents this mistake.

You should also expect to see fine, branching vessels (especially with age and sun exposure), regular round follicular openings, and an even background tan or brown tone in sun-exposed individuals. Solar lentigines (age spots) are a common and benign finding on sun-exposed facial skin.

Scalp

The scalp combines hair-bearing skin with significant vascularity and variable sun exposure depending on hair coverage. The dominant feature is regularly spaced hair follicle openings, with pale to pink interfollicular skin between them. Fine, regular vessels are visible between follicles, and in darker phototypes, pigment may outline the follicular units in a honeycomb pattern.

Normal variants include visible vessels that increase with age and in fair skin, variable hair density across different scalp regions, and benign seborrhoeic changes (yellowish scale).

Trunk and limbs — the classic view

This is where the textbook pigment network lives. Melanocytic lesions on the trunk (back, chest, abdomen) and proximal limbs typically show the regular honeycomb mesh described earlier in this module. The network should be symmetric and relatively uniform in thickness, with even distribution of background pigment. This is the easiest site to learn, and the one most dermoscopy teaching focuses on.

On the limbs, the pigment network is similar to the trunk but often finer. An important point: limb skin varies from proximal (more trunk-like) to distal (transitioning toward acral patterns at the hands and feet). Vessels are more visible on the limbs than the trunk, especially on the lower legs.

Lower leg skin deserves particular mention — it commonly shows increased vascularity with age, and stasis changes (brownish discolouration and prominent vessels from chronic venous insufficiency) are a frequent and benign finding in older adults.

Palms and soles (acral skin)

The skin on your palms and soles is uniquely structured — it has thick ridges (the lines of your fingerprints and footprints) and deep furrows between them, with no hair follicles. Under dermoscopy, this creates distinctive patterns unlike anything seen elsewhere on the body. The classic honeycomb network is absent here.

Normal acral lesions show one of several recognised patterns:

• Parallel furrow pattern — pigment running along the sulci (furrows). This is the most common benign acral pattern.
• Lattice-like pattern — pigment in the furrows with crossing lines
• Fibrillar pattern — fine lines running perpendicular to the sulci, common on weight-bearing soles
• Crista dotted pattern — dots of pigment sitting on top of the ridges

The key principle for acral dermoscopy is that benign pigment tends to follow the sulci (furrows). When pigment instead follows the ridges — called the parallel ridge pattern — this is a concerning finding that warrants further evaluation, as it is associated with acral melanoma.

Pigmentation intensity on acral skin varies with phototype, weight-bearing areas show different patterns from the arch, and transition zones at the edges of the palms and soles may show hybrid patterns.

Nails and periungual skin

The nail unit has distinct anatomy: the nail plate, nail bed, matrix, and surrounding skin folds. Normal nails appear smooth and translucent, with fine regular longitudinal lines running the length of the plate. The lunula (pale half-moon at the base) varies in visibility between individuals.

Pigmented bands in the nail plate — known as longitudinal melanonychia — are a common finding, particularly in people with darker skin. A regular, uniform brown band with consistent width and colour is usually benign. Irregularity in width, colour, or borders is a reason for further evaluation. Longitudinal ridging increases with age and is a normal finding.

The periungual skin (around the nail) shows normal skin patterns, and fine capillaries are visible at the nail fold — these can be useful in assessing connective tissue conditions, though that is beyond the scope of this module.

Mucosal and semi-mucosal sites

Lips, genital mucosa, and conjunctivae have their own distinct appearance under dermoscopy. Lips typically show a homogeneous pink-red colour with fine vessels and no network pattern. Genital mucosa shows structureless pink zones with visible vessels.

Normal variants at these sites include Fordyce spots (ectopic sebaceous glands appearing as small yellowish bumps on lips and genitalia) and melanotic macules in darker phototypes.

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