Summary Background Becker's naevus (BN) may represent a distressing cosmetic handicap and a challenging issue regarding treatment.
Objectives To compare clinical and histopathological findings of patients with BN treated with two different lasers: an erbium:yttrium–aluminium–garnet (Er:YAG) system vs. a neodymium:YAG (Nd:YAG) laser.
Patients and methods In this prospective and comparative study we present the clinical and histopathological evolution during a 2-year follow-up of 22 patients with BN treated with only one pass of the Er:YAG laser (n = 11) or three treatment sessions with the Q-switched Nd:YAG system (n = 11).
Results Clinical evaluation 2 years after treatment with the Er:YAG laser showed complete clearance (100%) in 54% of the patients (n = 6) and clearance of > 50% in 100% of the subjects. In relation to Nd:YAG laser treatments our results echo those of other authors. Numerous sessions are necessary to get an acceptable clinical clearance rate. Only one patient showed marked clearance (51–99%) after three treatment sessions. Moderate (26–50%) and mild (1–25%) clearance was observed in 45·5% (n = 5) and 27·3% (n = 3) of the patients.
Conclusions Both Er:YAG and Nd:YAG are safe tools to treat BN. However, in terms of pigment removal, one pass with Er:YAG is a superior technique to three treatment sessions with the Nd:YAG.