Stopping short of whitening cleared ABNOM equally, with a fifth of the pigmentation

Design

Randomised, evaluator-blinded, split-face trial, single centre

Population

30 Asian patients with ABNOM, Fitzpatrick skin types III–V

Primary outcome

Clearance (Global Aesthetic Improvement Scale) and adverse effects after 3 sessions

Effect

Similar clearance; PIH 4.8% vs 22.6% and scabbing 9.5% vs 61.9% (non-whitening vs whitening)

Acquired bilateral naevus of Ota-like macules (ABNOM) is common in Asian skin, and laser treatment carries a real risk of post-inflammatory hyperpigmentation. This single-centre, evaluator-blinded split-face trial treated 30 Asian patients with Fitzpatrick skin types III–V using a 755-nm picosecond alexandrite laser for three sessions six months apart.

One side was treated to the conventional endpoint of immediate whitening, using a smaller spot and higher fluence. The other used a larger spot and lower fluence chosen by a computational model to disrupt melanosomes without whitening. Clearance was high and similar on both sides. Post-inflammatory hyperpigmentation occurred in 22.6% of whitening-endpoint treatments and 4.8% of non-whitening ones, and scabbing in 61.9% versus 9.5%. Two-thirds of patients preferred the non-whitening side.

The trial is small and single-centre, and the exact parameters came from a model that other clinics may not replicate. But the principle, that immediate whitening is not a necessary endpoint for dermal pigment in darker skin, is directly relevant to Indian laser practice, where post-inflammatory hyperpigmentation is the complication patients fear most. It was published in May 2026.

• Consider a larger spot size and lower fluence, aiming short of immediate whitening, when treating ABNOM in skin types III–V.
• Warn patients that post-inflammatory hyperpigmentation was about five times more common with the whitening endpoint in this trial.
• Allow long intervals between sessions; this trial used six months.
• Test parameters on a small area first, since the model-derived settings may not transfer exactly to other devices.
• Use strict photoprotection between sessions to limit pigmentary complications.

Why it matters

It challenges the assumption that immediate whitening is needed to clear dermal pigment.

Don't overread it

Thirty patients at one centre with a model-derived setting is early evidence, not a validated protocol for every device.

The statistics, in plain English

In a split-face design each patient is their own control, which removes differences between people and makes a small trial more efficient. The pigmentation difference (22.6% vs 4.8%) is large, but with 30 patients the true gap could be smaller or larger; no confidence interval was given in the abstract.

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