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Background and Objectives An evaluation of the histological effects of a 2,940 nm fractional erbium:YAG (Er:YAG) laser device with adjustable depth and coagulation settings in a human abdominoplasty model. The goal of this study was to use light and confocal microscopy to determine the dimensions of the microthermal zones (MTZs) created by this device in the epidermal and dermal layers. Study Design/Materials and Methods Three subjects were consented and treated after being randomly assigned to a laser depth of either 250 µm, 500 µm, or 1,000 µm. Four coagulation levels were tested in each subject. Two biopsies were taken immediately, 1 and 2 weeks post-treatment from each zone and viewed by light and confocal microscopy. Two blinded observers examined the sections for changes in collagen and measured depth and width of the MTZs. Coagulation was assessed and recorded as the depth and width of denaturation; measured as the depth and width of ablation plus surrounding thickness of thermal necrosis from dissipated heat. Results Light microscopy findings in all treated samples showed a perforated epidermis and dermis immediately after treatment. The depths of ablation produced did not accurately reflect the three different laser settings. Depths of denaturation also did not increase with increased coagulation level settings as expected. The width of ablation in the MTZs, a non-adjustable setting, was the most accurate and reproducible in all subjects. Confocal microscopy samples revealed the presence of collagen remodeling in the dermis, which increased significantly at 1 and 2 weeks post-treatment. Conclusions Treatment with the 2,940 nm Er:YAG device led to significant changes of the dermis at light microscopy levels. The adjustable laser depth and coagulation settings did not produce predictable depths of ablation or denaturation, possibly as a result of the variation of tissue hydration properties among individuals. Increased collagen remodeling was seen in the dermis in all subjects at 1 and 2 weeks post-treatment. Lasers Surg. Med. 42:79–91, 2011 © 2011 Wiley-Liss, Inc.

An evaluation of the histological effects of a 2,940 nm fractional erbium:YAG (Er:YAG) laser device with adjustable depth and coagulation settings in a human abdominoplasty model. The goal of this study was to use light and confocal microscopy to determine the dimensions of the microthermal zones (MTZs) created by this device in the epidermal and dermal layers.Three subjects were consented and treated after being randomly assigned to a laser depth of either 250 µm, 500 µm, or 1,000 µm. Four coagulation levels were tested in each subject. Two biopsies were taken immediately, 1 and 2 weeks post-treatment from each zone and viewed by light and confocal microscopy. Two blinded observers examined the sections for changes in collagen and measured depth and width of the MTZs. Coagulation was assessed and recorded as the depth and width of denaturation; measured as the depth and width of ablation plus surrounding thickness of thermal necrosis from dissipated heat.Light microscopy findings in all treated samples showed a perforated epidermis and dermis immediately after treatment. The depths of ablation produced did not accurately reflect the three different laser settings. Depths of denaturation also did not increase with increased coagulation level settings as expected. The width of ablation in the MTZs, a non-adjustable setting, was the most accurate and reproducible in all subjects. Confocal microscopy samples revealed the presence of collagen remodeling in the dermis, which increased significantly at 1 and 2 weeks post-treatment.Treatment with the 2,940 nm Er:YAG device led to significant changes of the dermis at light microscopy levels. The adjustable laser depth and coagulation settings did not produce predictable depths of ablation or denaturation, possibly as a result of the variation of tissue hydration properties among individuals. Increased collagen remodeling was seen in the dermis in all subjects at 1 and 2 weeks post-treatment.

A 4-year-old boy was referred to the outpatient dermatology clinic for two growths on his scalp. The first lesion had been present on the vertex scalp for six months and was asymptomatic except for recent inflammation and drainage of white exudate. A second growth developed on the patient’s posterior parietal scalp in recent weeks and reportedly resembled the original appearance of the initial lesion. Review of systems was negative, and the parents denied any affected close contacts. There had been no intervention to the lesions. On examination, the vertex of the scalp revealed a 0.3 cm hemorrhagic crusted papule with surrounding desquamation and minimal surrounding erythema. The left posterior parietal scalp had a 0.2 cm smooth pearly papule. The remainder of the examination was unremarkable. The skin overlying the parietal scalp lesion was incised using a 19-gauge needle. A white, cheesy central core was removed with a comedone extractor (figure 1A▶). The specimen was then squashed with firm pressure between two glass microscope slides (figure 1B▶). The top slide was discarded, and the material on the bottom slide was stained with 3 ml of Giemsa stain (figure 1C▶). The slide was then gently rinsed with tap water. A single drop of mineral oil was applied to the air-dried specimen, followed by placement of a coverslip over the specimen. The slide was then viewed with light microscopy (figure 2▶). Cytologic examination revealed uniform, discrete and clustered purple ovals consistent with the large cytoplasmic viral inclusions of Molluscipoxvirus (Henderson-Paterson bodies), thus confirming the diagnosis of molluscum contagiosum (MC). As this was the only intact lesion on the full body exam of the child, the removal and squash preparation of the lesion’s contents was not only diagnostic, but therapeutic as well. No further treatment was required. Figure 1: (A) After incision with a 19-gauge needle, a comedone extractor is used to express the molluscum cheesy core. (B) The molluscum core is squashed between two glass microscope slides. (C) The squashed molluscum core is stained using 5 to 7 drops of Giemsa ... Figure 2: Discrete and clustered purple ovals consistent with large cytoplasmic viral inclusions of Molluscipoxvirus (Henderson-Paterson bodies), magnification x20. Inset: Magnified view of Henderson-Paterson body (arrow).