Impact of Sunscreens on Preventing UVR-Induced Effects in Nevi

Abstract

IMPORTANCE Sun damage is the most important environmental factor associated with malignant melanoma. To address the health threat, as well as the economic burden, primary prevention and early detection are crucial.OBJECTIVE To test the efficacy of a topical sunscreen in the prevention of UV-induced effects in nevi.DESIGN Prospective study of nevi protected by sunscreen vs a physical barrier.SETTING AND PATIENTS Twenty-three nevi from 20 patients attending a referral hospital.INTERVENTION Half of each nevus was protected by either a physical barrier or a sunscreen. Lesions were completely irradiated by a single dose of UV-B. MAIN OUTCOMES AND MEASURESIn vivo examination before and 7 days after irradiation and histopathologic-immunopathologic evaluation after excision on the seventh day. RESULTSThe most frequent clinical changes after UV radiation were pigmentation, scaling, and erythema; the most frequent dermoscopic changes were increased globules/dots, blurred network, regression, and dotted vessels. Both physical barrier-and sunscreen-protected areas showed some degree of these changes. More than 30% (7) of nevi did not show any change on clinical examination, and 18% (4) had no dermoscopic change. Immunohistopathologic differences between the halves of each nevus were demonstrable even when in vivo examination detected nothing. Parakeratotic scale, increased number and activation of superficial melanocytes, and keratinocyte proliferation were the most remarkable features. The only difference between both barriers was more enhanced melanocytic activation and regression features in the sunscreen group. No phenotypic features were found to predict a specific UV-B response.CONCLUSIONS AND RELEVANCE Both physical barriers and sunscreens can partially prevent UV-B effects on nevi. Subclinical UV radiation effects, not always associated with visible changes, can develop even after protection. Sunscreens are not quite as effective as physical barriers in the prevention of inflammatory UV-B-induced effects.

Temporal Trends in the Incidence and Mortality of Skin Malignant Melanoma in China from 1990 to 2019

“…Primary prevention and early detection are crucial to addressing the health threat and economic burden of SMM [ 40 ]. We recommend that the general population should take measures to minimize their exposure to risk factors, such as avoiding exposure to intermittent high-dose sunlight as well as other types of ultraviolet radiation.…”

“…We recommend that the general population should take measures to minimize their exposure to risk factors, such as avoiding exposure to intermittent high-dose sunlight as well as other types of ultraviolet radiation. Studies have indicated that although correctly using sunscreen can reduce the SMM incidence [ 40 ], traditional protection methods (e.g., wearing protective clothing and avoiding sun exposure or prolonged sunbathing) are more effective in reducing the melanoma risk [ 40 , 41 ], and these measures cannot be replaced by sunscreen use [ 42 ]. To optimize protection from the damaging effects of the sun, we should, therefore, not just “slop on the sunscreen” but also “slip on a t-shirt, slap on a hat, seek shade, and slide on sunglasses.” Importantly, these measures should be implemented together, not just one or some of them [ 42 ].…”

Discriminating Nevi from Melanomas

“…Several studies have demonstrated melanocytic activation and cell proliferation in nevi after a single dose of UV-B. 48,49 Inflammation-induced changes and melanocytic activation can in fact be observed in vivo, with RCM revealing the presence of intraepidermal dendritic cells and bright particles at DEJ and papillary dermis. If RCM features were evaluated in isolation and without knowledge that the nevus was recently irradiated by UVR, the RCM features would lead to the false diagnosis of melanoma (presented by Takigami MC et al at the 73rd American Academy, San Francisco, unpublished data, 2015).…”

UV Irradiation of Nevi: Impact on Performance of Electrical Impedance Spectroscopy and a Convolution Neural Network

“…After two UVB minimal erythema doses marked melanocytic activation was reported, avoided by physical and sunscreen protection [22]. Another study found that even after a single dose of UVB clinical and dermoscopic changes in nevi occurred, partially prevented by physical barriers or sunscreens [23]. Moreover, a positive correlation of the extent of morphological changes with increasing total…”