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Skin analysis for pigment disorders and melasma, separating UV from visible pigment

Melasma, solar lentigo and post-inflammatory hyperpigmentation look clinically similar but sit at different depths in the skin. We show what the 3D skin analysis contributes to the differential workup, how the Modified MASI score can be used as a longitudinal metric, and where the limits for advertising sit.

Updated 23 May 2026 · 7 min read

Pigment disorders are one of the most common indications in dermatology, particularly in female patients. The differential diagnosis between melasma, solar lentigo, post-inflammatory hyperpigmentation (PIH) and ephelides requires clinical experience and sometimes a Wood's lamp examination. 3D skin analysis with UV mode adds an additional layer that is not standardised in the Wood's lamp: a quantitative UV map with regional coordinates and longitudinal comparability.

What the UV capture shows for pigment

UV light at 365 nm is absorbed more strongly in the upper skin layer (epidermis) than in the dermis. Pigment sitting in the epidermis is rendered with markedly higher contrast under UV than pigment lying deeper in the upper dermis. This methodological property helps with classification:

  • Solar lentigo: mostly epidermal, sharp borders, markedly enhanced in UV.
  • Epidermal melasma: epidermal location, enhanced in the UV capture; typically symmetric on cheeks, forehead, upper-lip region.
  • Dermal melasma: deeper pigment in the papillary dermis, less enhanced under UV than in visible light, which helps differential diagnosis.
  • Post-inflammatory hyperpigmentation (PIH): acne-scar pigment, often along former lesions. UV enhancement varies by depth.
  • Ephelides (freckles): sharply outlined, epidermal, UV-strong.

This classification is orientational, not histologically conclusive. With unclear clinical findings, dermatoscopy and possibly histology remain the standard, particularly to exclude lentigo maligna.

What the polarised captures add

Cross-polarised capture reduces surface reflection and makes visible pigment more precise. The software on the report maps the visible pigment clusters onto the UV map and thereby shows side by side what is visible under normal light and what additionally appears under UV. Patient reactions to the UV finding are regularly strong, because the UV capture often shows more pigment than the mirror.

Modified MASI score as a longitudinal metric

The Modified Melasma Area and Severity Index (mMASI) is the established clinical score for longitudinal quantification. Four facial regions (forehead, right cheek, left cheek, chin) are evaluated by area share and pigment density, the product summed to a total score. Studies on Q-switched Nd:YAG laser plus tranexamic acid (combined therapy) show mMASI reductions in the mid to high percent range (see sources section); the exact effect is regimen and patient-specific.

The 3D skin analysis does not replace the mMASI score, it adds reproducible image documentation. Some practices capture the mMASI clinically for entry severity, the report then provides the longitudinal image for comparison after 3, 6 and 12 weeks.

Progression across treatment options

Established treatment options for melasma currently include:

  • Topical: hydroquinone, tretinoin, azelaic acid (Kligman regimen, triple combination)
  • Tranexamic acid systemic or topical: reduces melanocyte activity, increasingly used in combination with laser
  • Q-switched Nd:YAG laser: often at lower fluence (low-fluence protocol), specific for melasma
  • IPL (intense pulsed light): for epidermal pigment, less suited for dermal melasma because the pigment sits deeper
  • Sun protection: SPF 50+, mineral, year-round — the most important and most underestimated pillar

IPL therapy needs care: in melasma, IPL can cause paradoxical hyperpigmentation if energy is too high or pigment too deep. The UV capture of the pre-therapy report helps assess whether the pigment is sufficiently epidermal for IPL.

What to avoid

Three traps we see in practices working with skin analysis on pigment:

  • Before/after advertising with the report: Prohibited under § 11 HWG, and since the BGH ruling of 31.07.2025 (case I ZR 170/24) also for minimally invasive procedures. The report stays in the record and in the personal consultation.
  • Guaranteeing treatment success: Melasma is a chronic indication with a tendency to relapse. The report comparison must not gloss over this.
  • UV capture as diagnosis substitute: Lentigo maligna in the UV image looks similar to solar lentigo. With unclear findings, dermatoscopy and possibly histology, never just the device.

Practice setup for the pigment consultation

First consultation: history (sun exposure, pregnancy, hormones, medication, ethnic background), clinical inspection and dermatoscopy, then skin analysis with UV mode as report documentation. The report goes to the patient as an email link. Follow-up appointments after 6 to 12 weeks with identical capture position, the comparison block in the report shows the UV-marker change per region.

Sources and further reading

As of May 2026. This article is professional information for medical practices, not therapy advice in the individual case. Study citations are orientational; transferability to the individual patient remains a clinical assessment.

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