Prospective comparison study of a 550 picosecond 755 nm laser vs a 50 ns 755 nm laser in the treatment of nevus of Ota.

Since the introduction of selective photothermolysis, Q-switched nanosecond lasers have been used for the treatment of dermal pigmented lesions. Over the past several years, picosecond lasers have been introduced to the cosmetic community. We recently performed a study comparing a 550 picosecond 755 nm laser versus a 50 ns 755 nm laser, with the purpose of evaluating the clinical efficacy and complications of each laser when treating nevus of Ota. Ten Asian patients with nevus of Ota were enrolled in the study. Each lesion was split into 2 parts, and patients were treated with a 755 nm picosecond laser (PSL) and a 755 nm nanosecond laser (NSL). The clinical endpoint for fluence choice was immediate whitening (PSL: 2.33 ~ 3.36 J/cm2, NSL: 5.5 ~ 7 J/cm2) of the treated area. The pulse duration was fixed at 550 picoseconds (PSL) and 50 ns (NSL). The spot size of each laser was 2.5-3 mm. Laser treatments were performed until excellent clinical improvement was observed. Patients were examined 1 week after the first treatment, at each follow-up visit, and 6 months after the last laser treatment. The average number of treatment sessions to achieve excellent clinical improvement was 4.2 treatments using PSL and 5.4 treatments using NSL. One case of hyperpigmentation and one case of hypopigmentation were observed in the NSL treatment group. There were no complications in the PSL treatment group. The 755 nm 550 picosecond laser is significantly more effective than the 755 nm 50 ns laser in the treatment of nevus of Ota. The PSL treatment group also had minimum side effects.

Mechanism of crescent-shaped and ring-shaped epidermal damage from laser hair removal with cryogen spray cooling.

The safety and efficacy of laser hair removal have been well established through many clinical studies and through clinical use over the past 25 years. A laser hair removal device that protects the epidermis by utilizing cryogen spray cooling (CSC) is widely used internationally. In darker skin types, post-inflammatory hyperpigmentation (PIH) can occur after laser hair removal. In particular, laser hair removal with CSC is known to cause crescent-shaped or ring-shaped PIH. In this experiment, we report a visualization of this PIH mechanism. The laser used in this experiment is a 755-nm-long-pulsed alexandrite laser. Graph paper was treated with this laser to assess for thermal damage. We investigated changes in thermal damage due to differences in laser spot size, fluence output, and laser beam angle in relation to the graph paper. When using a spot size of 18 mm, we observed that higher fluences caused crescent-shaped thermal damage on the margins of the treated graph paper. It was also confirmed that when the hand piece is not held perpendicular to the skin, the laser-treated area is expanded and the CSC range is narrowed. These factors caused the area of thermal damage to widen. This widening causes ring-shaped thermal injury, leading to PIH. We treated graph paper using a hair removal laser with CSC to investigate the mechanism of crescent or ring-shaped thermal damage. Laser treatment on graph paper is effective as a test for defects in the CSC device. Factors that cause inadequate cooling, which leads to PIH, are large spot size, high fluence, not holding the laser hand piece perpendicular to the skin, and malfunctioning of CSC device.

Long-term results of nail correction with double wires for pincer nail deformity: A retrospective cohort study.

There is no consensus on the best treatment for pincer nail deformity. We developed a novel procedure that uses double wires to treat pincer nail deformity on the great toe. This study aimed to describe this technique for pincer nail deformity treatment and present the long-term findings/observations. After injecting a local anesthetic, a mini router was used to make holes on both sides of the nail plate edge, and the wire was inserted in two places, one proximal and the other distal to the great toenail. The wire was removed when it moved to the tip of the great toe as the nail grew. Patients who underwent this method were evaluated retrospectively from 2014 to 2020. Patients with less than 24 months of follow-up were excluded. If pain occurred again, it was deemed as a recurrence. A total of 27 patients (36 toes, mean age: 69.5 years) were evaluated. In all cases, the pain disappeared 1 week after the procedure. In the correction period (mean 2.7 months), six toes had complications (nail break, four toes and nail hold pain, two toes), while recurrence occurred in four toes within 2 years. Curvature (nail tip height/width of nail tip × 100%) improved significantly up to 1-year post-procedure (37.7 ± 14.4%, p < 0.05) as compared to pre-correction (53.8 ± 24.7%). The procedure time was short (approximately 10 minutes), and the treatment was completed with a single procedure. In addition, the recurrence rate was low.

Treatment of Ecchymosis with a Pulsed Dye Laser.

Ecchymosis is a common side effect after injury and surgery. A pulsed dye laser (PDL) is the gold standard for vascular lesions and can minimize ecchymosis. Heating induces hemoglobin modification due to oxidative and heat reactions with the formation of bilirubin and methemoglobin, resulting in color changes to brown-yellow. Therefore, downtime following cosmetic procedures can be shortened.

A Case of Occipital Malignant Peripheral Nerve Sheath Tumor with Neurofibromatosis Type 1.

INTRODUCTION: The prognosis of malignant peripheral nerve sheath tumor (MPNST) with neurofibromatosis type 1 (NF-1) is worse than that of a solitary MPNST, because of the tumor size and location difficult to resect completely. We experienced a case of MPNST in the occipital region with NF-1. CASE REPORT: A 59-year-old woman presented with NF-1 and an MPNST of the occipital region. We performed wide excision involving the occipital bone, and reconstructed with a titanium plate and a free latissimus dorsi muscle flap. Despite three operations and postoperative radiotherapy, the tumor locally recurred after each surgery; further complicated by lung and mediastinal metastasis. Adjuvant therapy was insufficient to control local recurrence, which was observed intracranially, resulting in sagittal sinus invasion. Thirty months after the initial surgery, the patient died of respiratory failure due to lung metastasis. CONCLUSION: MPNST with NF-1 has poorer prognosis than that of a solitary lesion. Recently, it is reported in several literature that combination therapy with surgery and radiotherapy improve survival rates. But as we presented, when the complete local resection with free margin could not achieved due to the size and anatomical location of the tumor, the effectiveness of radiotherapy is not sufficient to control local recurrence.

An Adverse Implication of Radiation Therapy for Implant-Retained Maxillofacial Prostheses.

We report the 19-year postoperative course of a patient whose maxillary defect was reconstructed with maxillofacial implant-retained facial prostheses. The patient received 60 Gy of radiation therapy. Adjunctive hyperbaric oxygen therapy was administered and four 4.0-mm long maxillofacial implants were inserted. Four years and 6 months after insertion surgery, two of the four implants were lost and the others showed bone regression in the surrounding bone. All implants were replaced with Epitec System maxillofacial implants placed in non-irradiated bone. Eleven years and 6 months after replacement, the Epitec System has been maintaining good and firm osseointegration. Appropriate selection of implant sites and no history of radiation therapy are keys to successful implant reconstruction. However, adjunctive hyperbaric oxygen therapy is believed to be effective, osseointegrated implant should be inserted at a point appropriately distant from an irradiated lesion.