Melasma: a comprehensive update: part I

Melasma is a common disorder of hyperpigmentation affecting millions of people worldwide. While it is thought to be triggered or exacerbated by sun exposure and hormones, much remains to be understood about its pathogenesis. A thorough understanding of the etiology of melasma and the research tools available to study this condition are crucial to enhancing management and developing novel targeted therapies of this often frustrating condition.     

Melasma: a comprehensive update: part II

Several methods of treatment are available to patients with melasma. First-line therapy usually consists of topical compounds that affect the pigment production pathway, broad-spectrum photoprotection, and camouflage. Second-line therapy often consists of the addition of chemical peels, although these must be used cautiously in patients with darker skin. Laser and light therapies represent potentially promising options for patients who are refractory to other modalities, but also carry a significant risk of worsening the disease. A thorough understanding of the risks and benefits of various therapeutic options is crucial in selecting the best treatment.     

Raynaud phenomenon in dermatology : Part 2: therapy

While primary Raynaud phenomenon (RP) only rarely leads to complications, secondary RP when associated with systemic sclerosis (SSc) frequently results in necrosis, ulcers or even gangrene. Therefore timely therapeutic intervention is required. Management of RP includes physical therapy, avoidance of triggers, and a variety of medications, depending on the disease severity. On the basis of published studies and of our own experience we suggest: a) for primary and uncomplicated secondary RP, calcium channel blockers in adequate doses; b) for SSc-associated secondary RP with hypertension, cardial or renal involvement, drugs which interfere with angiotensin; c) in case of concomitant depression, exploitation of the vasodilatory effects of serotonin reuptake inhibitors, d) in presence of ulcers or marked trophic alterations, intravenous administration of iloprost, e) for recalcitrant cases and endangered digits, sildenafil, f) for prevention of severe relapses, the endothelin-receptor antagonist bosentan. The drugs mentioned in c-f are not approved for RP and used off-label. In patients with secondary SSc-associated RP, timely therapy can reduce the percentage of complications such as ulcers or amputations. In addition, timely treatment of RP possibly retards ensuing fibrotic processes.     

Cellulite: Advances in treatment: Facts and controversies

Cellulite is traditionally considered a highly prevalent aesthetic condition in women. From a clinical standpoint, it is characterized by a cottage-cheese-like appearance of the skin, which can be most commonly found in certain areas of the body (eg, thighs, buttocks, and legs). Although cellulite is generally asymptomatic, the more severe stages can be accompanied by the appearance of painful nodules and increased local temperature, which are suggestive of an inflammatory reaction occurring in the dermis and in the underlying subcutaneous adipose tissue. Whether cellulite is a real disease or only a disturbing aesthetic issue is still a matter of controversy. This debate notwithstanding, it seems clear from market trends that there is considerable commercial interest in developing effective strategies aimed at reducing the cottage-cheese–like appearance of cellulite areas. Quite disturbingly, the majority of treatment attempts to date have been conducted in an empirical manner and without the application of rigorous scientific methodology. This is likely due—at least in part—to the lack of major, evidence-based pathophysiological insights into the nature of this condition. More stringent regulatory control is needed over commercial products aiming at improving the appearance of cellulite.     

Biostatistics Series Module 3: Comparing Groups: Numerical Variables

Numerical data that are normally distributed can be analyzed with parametric tests, that is, tests which are based on the parameters that define a normal distribution curve. If the distribution is uncertain, the data can be plotted as a normal probability plot and visually inspected, or tested for normality using one of a number of goodness of fit tests, such as the Kolmogorov–Smirnov test. The widely used Student''s t-test has three variants. The one-sample t-test is used to assess if a sample mean (as an estimate of the population mean) differs significantly from a given population mean. The means of two independent samples may be compared for a statistically significant difference by the unpaired or independent samples t-test. If the data sets are related in some way, their means may be compared by the paired or dependent samples t-test. The t-test should not be used to compare the means of more than two groups. Although it is possible to compare groups in pairs, when there are more than two groups, this will increase the probability of a Type I error. The one-way analysis of variance (ANOVA) is employed to compare the means of three or more independent data sets that are normally distributed. Multiple measurements from the same set of subjects cannot be treated as separate, unrelated data sets. Comparison of means in such a situation requires repeated measures ANOVA. It is to be noted that while a multiple group comparison test such as ANOVA can point to a significant difference, it does not identify exactly between which two groups the difference lies. To do this, multiple group comparison needs to be followed up by an appropriate post hoc test. An example is the Tukey''s honestly significant difference test following ANOVA. If the assumptions for parametric tests are not met, there are nonparametric alternatives for comparing data sets. These include Mann–Whitney U-test as the nonparametric counterpart of the unpaired Student''s t-test, Wilcoxon signed-rank test as the counterpart of the paired Student''s t-test, Kruskal–Wallis test as the nonparametric equivalent of ANOVA and the Friedman''s test as the counterpart of repeated measures ANOVA.