BACKGROUND Picosecond pulse duration lasers (PS) have altered the field of dermatology. PS were initially used in tattoo removal, to optimize efficacy and reduce side effects with nanosecond domain lasers. More recently, they have been demonstrated to be effective in the treatment of pigmentary disorders, acne scarring, and photoaging. OBJECTIVE In this article, we critically analyze the published data on the many uses of picosecond lasers in dermatology. MATERIALS AND METHODS A systematic review of PubMed was conducted using the following search terms: “picosecond,” “picosecond laser,” “picosecond laser dermatology,” “picosecond laser pigment/pigmentation,” and “picosecond laser tattoo removal.” Articles ranged from 1988 until 2017. RESULTS Forty-one articles were identified, and 27 met inclusion criteria for review. Indications for the PS included a variety of dermatologic applications include tattoo removal, benign pigmented lesions/pigmentary disorders, acne scarring, and photoaging. Most studies demonstrated safe and effective treatment. CONCLUSION The development of the picosecond pulse duration is a breakthrough innovation in laser technology, changing the scope of laser treatment. Encouraging findings in tattoo pigment clearance spurred the use of PS in a wider array of dermatologic issues. The increasingly positive results and low incidence of adverse effects further substantiates PS efficacy for a variety of dermatologic uses.

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BACKGROUND Hyaluronic acid (HA) fillers have increased in popularity. Although complications are rare, knowledge regarding their prevention and management are crucial. The utility of preinjection aspiration has become controversial. OBJECTIVE Our study investigated the utility of preinjection aspiration as a safety checkpoint for HA fillers through comparison of physiochemical and rheological properties in an in vitro model. MATERIALS AND METHODS Whole blood was drawn from vacutainers using syringes containing 10 commonly used HA fillers. Each HA filler was examined with the plunger pulled back at volumes of 0.2 and 0.5 cc. The time required to visualize a flash was recorded. Data were compared using physiochemical and rheological properties, pullback volumes, and needle gauges. RESULTS Using a multivariable regression model, HA concentration, elastic modulus (G′), viscous modulus (G″), and complex modulus (G*) had significant relationships with time to flash, whereas needle gauge and pullback volume did not. However, when comparing pullback volume using an appropriate paired analysis, 0.5 cc pullback volume had a significantly decreased mean time to flash than 0.2 cc. CONCLUSION Preinjection aspiration may have utility as a safety checkpoint for HA fillers. Practitioners may have to adjust pullback volume and waiting time to visualize the flash based on physiochemical and rheological properties.

Epidermolytic ichthyosis (EI) due to KRT10 mutations is a rare, typically autosomal dominant, disorder characterized by generalized erythema and cutaneous blistering at birth followed by hyperkeratosis and less frequent blistering later in life. We identified two KRT10 mutations p.Q434del and p.R441P in subjects presenting with a mild EI phenotype. Both occur within the mutational "hot spot" of the keratin 10 (K10) 2B rod domain, adjacent to severe EI-associated mutations. p.Q434del and p.R441P formed collapsed K10 fibers rather than aggregates characteristic of severe EI KRT10 mutations such as p.R156C. Upon differentiation, keratinocytes from p.Q434del showed significantly lower apoptosis (P-value<0.01) compared with p.R156C as assessed by the TUNEL assay. Conversely, the mitotic index of the p.Q434del epidermis was significantly higher compared with that of p.R156C (P-value<0.01) as estimated by the Ki67 assay. Structural basis of EI phenotype variation was investigated by homology-based modeling of wild-type and mutant K1-K10 dimers. Both mild EI mutations were found to affect the surface-exposed residues of the K10 alpha helix coiled-coil and caused localized disorganization of the K1-K10 heterodimer. In contrast, adjacent severe EI mutations disrupt key intermolecular dimer interactions. Our findings provide structural insights into phenotypic variation in EI due to KRT10 mutations.