Treatment of Compound Melanocytic Nevus Using a Long-pulsed 755-nm Alexandrite Laser

Abstract

We herein report a 16-year-old Korean male patient with darkly pigmented mammillated compound melanocytic nevus effectively treated by a 755nm alexandrite laser with a pulse duration of 3 msec. Pigment-specific lasers are known to be effective in the treatment of acquired and congenital melanocytic nevi as they mainly target the chromophores of melanin pigments in nevus cells. In the present report, we proposed the use of an integrated dynamic cooling device that effectively protected the epidermis and facilitated safer delivery of high pulse energy of sufficient intensity to destroy large nests of compound nevus cells. Furthermore, a 755-nm alexandrite laser with a pulse duration of 3 msec shortened procedure times compared to conventional resurfacing lasers by eliminating the risk of post-therapy oozing or bleeding with selective photothermolysis, in addition to targeting a larger spot size.

Sequential delivery of long‐pulsed 755‐nm alexandrite laser and long‐pulsed 1,064‐nm neodymium:yttrium‐aluminum‐garnet laser treatment for pigmented disorders

“…Accordingly, the use of a LP 755‐nm Alex laser would, theoretically, disintegrate tattoo particles more effectively and produce less vacuolar reactions to the surrounding tissues, compared to a LP 1064‐nm Nd:YAG laser. However, lightly pigmented lesions or deeply located lesions would require additional sessions of LP Alex laser treatment or combined treatment with ablative lasers . Thus, we presumed that a combined treatment with LP 755‐nm and LP 1064‐nm laser pulses would generate greater photoacoustic and photothermal effects on target pigment particles and surrounding tissue components, compared to treatment with a LP 755‐nm laser alone or a LP 1064‐nm laser alone.…”

“…However, high risks of recurrence and side effects, including prolonged post‐treatment erythema, post‐inflammatory hyperpigmentation, and hypertrophic or atrophic scarring, limit the use of ablative lasers, particularly in Asian patients with large pigmented nevus lesions. For these, non‐ablative long‐pulsed (LP) lasers at pulse durations of 1‐300 ms have been suggested as additional or alternative treatment modalities to theoretically destroy nests of nevi cells by selectively targeting pigment chromophores …”

“…The following parameters for LP 532‐nm Nd:YAG lasers for treating small acquired melanocytic nevi have been suggested a pulse duration of 20 ms, a spot size of 2 mm, and a fluence of 30‐50 J/cm 2 . Meanwhile, LP 755‐nm Alex lasers have been used at a pulse duration of 3 ms, a spot size of 5‐6 mm, and a fluence of 30‐35 J/cm 2 . Pretreatment with an ablative Er:YAG laser at a pulse duration of 100 μs, an ablation depth of 25 mm, a spot size of 2 mm, and single or multiple passes with intermittent tissue wiping has been suggested for achieving better clinical outcomes before delivering LP Alex pulses .…”

“…1 Meanwhile, LP 755-nm Alex lasers have been used at a pulse duration of 3 ms, a spot size of 5-6 mm, and a fluence of 30-35 J/cm 2 . 2,6 Pretreatment with an ablative Er:YAG laser at a pulse duration of 100 μs, an ablation depth of 25 mm, a spot size of 2 mm, and single or multiple passes with intermittent tissue wiping has been suggested for achieving better clinical outcomes before delivering LP Alex pulses. 6 Nonetheless, conclusive data that support LP lasers as the single most effective and safe treatment modality for common acquired melanocytic nevus have not been reported, and optimized treatment parameters thereof still remain to be elucidated.…”

“…2,6 Pretreatment with an ablative Er:YAG laser at a pulse duration of 100 μs, an ablation depth of 25 mm, a spot size of 2 mm, and single or multiple passes with intermittent tissue wiping has been suggested for achieving better clinical outcomes before delivering LP Alex pulses. 6 Nonetheless, conclusive data that support LP lasers as the single most effective and safe treatment modality for common acquired melanocytic nevus have not been reported, and optimized treatment parameters thereof still remain to be elucidated. In this report, we macroscopically evaluated the patterns of LP laser-induced tissue reactions using a bovine serum albumin-polyacrylamide hydrogel, tissue-mimicking (TM) phantom, into which black tattoo particles were embedded.…”