Freckle

Abstract: The subject of lentigo has received scant attention in the American literature, and the term has usually been employed synonymously with "ephelis" or "freckle." Freckles are due to a prenatal concentration of melanoblasts, are light brown and are usually more prominent on exposed surfaces, especially following exposure to actinic rays. Dark brown macules on covered parts of the body, differing from freckles on microscopic examination, must be considered a distinct clinical entity. Unless modern staining methods for the study of pigment activity are employed, particularly Bloch's dopa reaction, Masson's trichrome stains and the silver method, histologic changes can easily be misinterpreted, and confusion in diagnosis and classification may result. We believe that the following case of a condition which we have labeled "generalized lentigo" presents sufficient features of interest to warrant a detailed report. REPORT OF A CASE History.—Miss V. M., aged 24, from Moberly, Mo., was first

Abstract: In order to better understand the geometrical effect on freckle formation in superalloys, samples with uniform increases and decreases in their cross sections were directionally solidified in a Bridgman furnace. In comparison to our conventional knowledge, some new features of freckle appearance have been observed. Freckles could occur at sloped surfaces where the freckle pattern is no longer roughly parallel to the direction of gravity but has the same slope as the surface. At significantly angled surfaces, the freckles appear as discrete flakes, having the shape of tree roots, instead of the long and narrow chains which are usually observed. The component portions having inward sloping surfaces are very freckle prone while those with outward sloping surface are mostly freckle free, although the completely opposite freckling tendency is indicated by the simulated solidification condition. Therefore, as an independent factor the geometrical feature of the components can more effectively affect the freckle formation than the local thermal conditions.

Abstract: Background: Melanocytic nevi (moles) and freckles are well known biomarkers of melanoma risk, and they are influenced by similar UV light exposures and genetic susceptibilities to those that increase melanoma risk. Nevertheless, the selective interactions between UV exposures and nevus and freckling genes remain largely undescribed. Methods: We conducted a longitudinal study from ages 6 through 10 years in 477 Colorado children who had annual information collected for sun exposure, sun protection behaviors, and full body skin exams. MC1R and HERC2 / OCA2 rs12913832 were genotyped and linear mixed models were used to identify main and interaction effects. Results: All measures of sun exposure (chronic, sunburns, and waterside vacations) contributed to total nevus counts, and cumulative chronic exposure acted as the major driver of nevus development. Waterside vacations strongly increased total nevus counts in children with rs12913832 blue eye color alleles and facial freckling scores in those with MC1R red hair color variants. Sunburns increased the numbers of larger nevi (≥2 mm) in subjects with certain MC1R and rs12913832 genotypes. Conclusions: Complex interactions between different UV exposure profiles and genotype combinations determine nevus numbers and size, and the degree of facial freckling. Impact: Our findings emphasize the importance of implementing sun-protective behavior in childhood regardless of genetic make-up, although children with particular genetic variants may benefit from specifically targeted preventive measures to counteract their inherent risk of melanoma. Moreover, we demonstrate, for the first time, that longitudinal studies are a highly powered tool to uncover new gene–environment interactions that increase cancer risk. Cancer Epidemiol Biomarkers Prev; 23(12); 2829–39. ©2014 AACR .