Limited research exists on laser treatment of giant congenital melanocytic nevus (GCMN).
We sought to elucidate the efficacy of the Erbium: YAG laser on GCMN and the histologic factors associated with a positive clinical response.
Between 2019 and 2022, we enrolled 30 medium-to-giant CMN patients who underwent Er: YAG laser treatment. All patients received biopsies before and after laser treatments. Clinical efficacy outcomes were evaluated by the investigator\'s global assessment (IGA), 5-point scale of depigmentation, and Vancouver Scar Scale (VSS) scores at least 6 months after treatment.
Of the 30 cases, 18 (60.0%) showed improvement (IGA score ≥3). Eight (26.7%) patients showed repigmentation. Eight (26.7%) patients developed hypertrophic scars. The average IGA, depigmentation, and VSS scores were 2.93, 3.57, and 3.20. The IGA score was higher (3.24 ± 1.18 vs. 2.22 ± 0.97, p = 0.031) and a lower repigmentation rate (14.3% vs. 55.6%, p = 0.032) was observed in the cases with Grenz zone. The IGA score was higher (3.33 ± 1.24 vs. 2.13 ± 0.89, p = 0.023) and the repigmentation rate was lower (11.1% vs. 50.0%, p = 0.034) also in the cases with the melanocytes nests with aggregation of melanin. Lesions with superficial ablation resulted in less hypertrophic scar formation than those with deep ablation (5.9% vs. 53.8%, p < 0.05).
The Er: YAG laser demonstrated effective clinical results for GCMNs. The grenz zone and the melanocytes nests with aggregation of melanin are promising predictors of laser efficacy.

Dissecting cellulitis of the scalp (DCS) is a rare recurrent inflammatory disease of unknown etiology. Ideal treatment of DCS remains unclear. We treated DCS with 2940-nm erbium Yttrium-aluminum-garnet (YAG) laser in 12 patients and assessed the efficacy by Physicians Global Assessment (PGA), number of inflammatory nodules, abscesses, and area of alopecia. After a mean treating session of 2.2 months, 10 patients reached PGA 0 (initial PGA 1) or 1 (initial PGA ≥2). At the end of treatment, there was 84%, 100%, and 74% regression in nodules, abscesses, and alopecia area, respectively. No severe adverse effect was observed. 2940-nm erbium: YAG laser may be an effective and safe way to treat DCS resistant to other therapies.

Becker\'s nevus (BN) is a cutaneous hamartoma of benign nature that develops through adolescence and affects mostly young men. The nevus is usually located unilaterally and is characterized by hypertrichosis and hyperpigmentation. Despite recent advances in treatment modalities, no effective treatment has been established for BN hyperpigmentation. We sought to assess the efficacy and safety of fractional Erbium: YAG 2940 nm and Q-switched Nd: YAG 1064 nm lasers in the treatment of BN hyperpigmentation. Twenty-three patients with BN were included in a prospective, randomized-controlled, observer-blinded, split-lesion comparative technique trial. In each patient, two similar square test regions were randomized to either be treated with a fractional Erbium: YAG 2940 nm laser or with a Q-switched Nd: YAG 1064 nm laser. Each patient was treated with three sessions at six-week intervals. At the follow-up, clearance of hyperpigmentation was assessed by physician global assessment, visual analogue scale, grade of improvement, patient global assessment, and patient satisfaction. Regions treated with the fractional Erbium: YAG 2940 nm laser demonstrated significantly better improvement compared to ones treated with the Q-switched Nd: YAG 1064 nm (p-value = 0.001) laser. Adverse effects such as repigmentation and hypertrophic scarring were not reported during the follow-up period. The outcomes were cosmetically acceptable with overall high satisfaction among the included patients. Our data suggest a superior role for the fractional Erbium: YAG (2940 nm) laser in the treatment of BN hyperpigmentation compared to the Q-switched Nd: YAG (1064 nm) laser, along with being a safer method and having no reported side effects.

Lichen amyloidosis (LA) is a type of primary localized cutaneous amyloidosis clinically characterized by persistent pruritic, hyperkeratotic papules commonly distributed on the shins and histopathologically characterized by amyloid deposits in the papillary dermis. The condition is difficult to treat though various treatment modalities have been tried. We report a case of LA treated successfully with Fractional ablative 2,940 nm Erbium: YAG Laser treatment. To the best of our knowledge, this is the first documented report of the successful use of fractional ablative laser in the treatment of LA.