Mohs math--where the error hides.

BACKGROUND: Mohs surgical technique allows a full view of surgical margins and has a reported cure rate approaching 100%. METHOD: A survey amongst Mohs surgeons was performed to assess operator technique. In addition, an animated clay model was constructed to identify and quantify tissue movement seen during the processing of Mohs surgical specimens. RESULTS: There is variability in technique used in Mohs surgery in regards to the thickness of layers, and the number of blocks layers are cut into. A mathematical model is described which assesses the clinical impact of this variability. CONCLUSION: Our mathematical model identifies key aspects of technique that may contribute to error. To keep the inherent error rate at a minimum, we advocate minimal division and minimal physical thickness of Mohs specimens.

Laser treatment of leg veins.

The development of lasers using deeper-penetrating, near-infrared wavelengths with millisecond pulse durations and skin-cooling methods has produced safer and more predictable results for the treatment of leg veins less than 1 mm in diameter and depth. Recent prospective studies of the near-infrared lasers show comparable efficacy and side effect profiles to those observed with sclerotherapy. Treatment of reticular and varicose veins is effective with these wavelengths but is limited by patient discomfort when compared with sclerotherapy. Visible light lasers (such as the pulsed dye and KTP) and intense pulsed-light sources are reproducibly effective only for superficial, nonarborizing pink-to-red telangiectasia, in the absence of points of proximal reflux. Because most lower-extremity vascular ectasias comprise a heterogeneous group of vessel sizes and depths, many patients achieve the best results using a combination of techniques. This article reviews the fundamentals of laser tissue interactions for the treatment of leg veins and details the recent clinical experience with the newer near-infrared devices.

A newly modified 595-nm pulsed dye laser with compression handpiece for the treatment of photodamaged skin.

BACKGROUND AND OBJECTIVES: The pulsed dye laser set the standard of care for the treatment of vascular lesions, and recent modifications have enabled improved efficacy with fewer side effects. An investigational high energy, variable pulse duration pulsed dye laser has been modified to treat both vascular and pigmented lesions associated with photoaging. Each laser pulse is comprised of a sequence of eight uniform micropulses, which evenly distribute the pulse energy, effectively increasing the purpura threshold at any given fluence. Pigmented lesions are treated with a compression handpiece (CHP) that removes competing vascular target from the field, and helps to prevent purpura. This pilot study was undertaken to determine the optimum laser settings, and to investigate the ability of this device to improve vascular and pigmented lesions associated with photoaging. STUDY DESIGN/MATERIALS AND METHODS: Twenty-four patients with photoaged skin and phototype I-III were enrolled in the study. Thirteen received treatment for vascular and pigmented lesions, and 11 subjects were treated for pigmented lesions alone. Subjects received one to three treatments at 3-4 weeks intervals, and underwent 3- and 12-week follow-up evaluation. The degree of improvement was assessed by subject evaluation as well as comparison of standardized digital photographs by three independent dermatologists. Background erythema was treated with a 12-mm spot size, at a fluence of 7 J/cm(2), and a pulse width of 10 ms. The cryogen cooling was set at 30 mseconds with a 30 ms delay. Individual telangiectasias were treated with a 5- or 7-mm spot size at fluences of 9-14 J/cm(2) and pulse widths of 6-20 mseconds. Pigmented lesions were treated using a 5- or 7-mm spot size, with energy of 9-15 J/cm(2) and a pulse width of 1.5-10 ms without cooling. The CHP had a 7-mm spot size, and fluences of 9-16 J/cm(2), and pulse widths of 1.5 or 3 ms were used in the treatment of pigmented lesions. RESULTS: The treatment was well tolerated without the use of topical anesthetic. All subjects noted improvement in the both vascular and pigmented lesions, and were satisfied with their outcomes. Objectively, there was moderate improvement in background erythema, telangiectasia, and pigmented lesions. Three subjects who were treated with sun tans developed transient hypopigmentation and two subjects developed a transient textural change following pulse stacking for the treatment of pigmented lesions with the conventional handpiece. Purpura was noted in all patients treated for pigment with the conventional handpiece at pulsewidths less than 6 mseconds, as compared to only one that was treated with the CHP. Three patients treated in rapid succession for vascular, and then pigmented lesions with the CHP exhibited purpura, which was prevented in future treatments with 1-2 minutes of topical ice cooling between passes. CONCLUSIONS: This novel 595-nm pulsed dye laser, with a modified pulse sequence and CHP, now has the versatility to safely treat both pigment and vascular changes associated with photoaging.