Background  Hypertrophic port-wine stains (PWS) usually respond poorly to pulsed dye laser treatment. The long-pulsed 1064 nm Nd:YAG laser can target deeper situated vessels and may therefore be more effective.

Objective  To evaluate the efficacy and safety of the Nd:YAG laser for the treatment of hypertrophic PWS.

Methods  In a retrospective cohort study, all hypertrophic PWS patients treated with the Nd:YAG laser between 2005 and 2011 were invited for follow-up. Clinical improvement was assessed using Physician Global Assessment (PhGA) and Patient Global Assessment (PGA).

Results  Assessment was obtained in 32 of 44 eligible patients (mean age 51.4 years), after a mean of 2.8 (SD ± 2.1) Nd:YAG laser treatments. Good or excellent improvement of hypertrophy was found in a majority of patients, both by PhGA (91%) and PGA (93%). Good or excellent improvement of colour was found in 63% of patients by PhGA, and in 87% by PGA. Recurrence of hypertrophy was seen in three patients. All but two patients would recommend Nd:YAG treatment to other patients. Mild to moderate scars were seen in seven patients, hypopigmentation in 14 patients.

Conclusion  The 1064 nm Nd:YAG laser is highly effective in the treatment of hypertrophic PWS with only a few treatments needed. Mostly mild side effects were seen in half of all patients. Hypertrophy seems to respond better than colour. To further improve colour, a combination with pulsed dye laser treatment is advisory. Observation of immediate clinical endpoints is important when using the Nd:YAG laser, to optimize outcomes and reduce side effects.