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Application
1590 99 002_1 - 21. February 2011 65
Treatment of lengitines with a diode laser at 808nm
S. McCoy; Laser, Skin & Vein Clinic, North Adelaide, South Australia
Background
Lentigines are common benign epidermal skin lesions which occur predominantly on sun-exposed
areas of individuals with fair (Fitzpatrick Types I-III) skin, increasing incidence with advancing age.
Histologically, solar lentigines exhibit elongation of the epidermal rete ridges and an increase in the
number of melanocytes and the amount of epidermal pigment.
Many different lasers have been used with a high degree of efficacy and low incidence of adverse
effects including Q-switched
Nd:YAG, ruby and aexandrite, frequency-doubled long-pulsed
Nd:YAG, Erbium YAG, ultra-short pulsed CO
2
and others. This study evaluated treatment of
lentigines with a long-pulsed 808 nm diode laser which is in common clinical use for the purpose of
hair reduction.
Materials and method
Twelve healthy consenting female adults, age range 44 to 74 years, exhibiting numerous (at least
10) lentigines on the dorsum of the hands and/or the arms participated in this trial. A long pulsed
808 nm diode laser (MeDioStar, Carl Zeiss Meditec, Jena, Germany) was used only in the Pro
mode single pulse without interval. Three patients were initially treated with a 12 mm spot. The
remaining 9 patients were treated with a 6 mm spot which allowed higher fluence with a shorter
pulse width. Treatment was carried out with a silicon spacer to hold the circular flat lens 1 mm from
the skin surface (in contrast to the recommended method of treatment for hair reduction which is
skin contact with clear gel coupling).
All patients were treated with energies commencing at 25 J/cm² and increasing in 5 J/cm²
increments until darkening of the lentigine within 5 minutes of treatment was observed. The
remainder of the lesions were treated at this fluence. One lentigo per patient located on the
posterior arm was treated at a pre-selected fluence and was biopsied immediately after the
treatment. A total of 12 biopsies were studied with 2 at each fluence from 25 an 50 J/cm². At
follow-up 4 weeks later the estimated percentage disappearance of lentigines was recorded as 0-
25%, 51-75% and 76-100%. Any adverse effects were noted.
Results
All patients showed 50% or greater reduction in lentigines at one month except one patient treated
with a 12mm spot and 30 J who showed only 25-50%. There was poor correlation between
clearance and fluence but strong correlation between clearance and color of the original lesions with
darker lesions showing greater clearance. There was no scarring at one month but some lesions
showed residual erythema at this short post-treatment interval. Histology consistently showed
streaking of the nuclear chromatin of the pigmented basal keratinocytes, clefting of a thin upper rim
of the papillary dermal collagen. The effects were more pronounced with the 6 mm than the 12 mm
spot.
Summary
A diode laser emitting 25 to 50 50 J/cm² at 808 nm is capable of inducing limited and focal necrosis
of solar lentigines in the forearm skin of Caucasian females with satisfactory clinical results.
Treatment is rapid and well tolerated. Results are more dependent on the color of the lentigino than
the fluence of the laser. Operator judgement and experience is therefore important in obtaining
good results.