This month's news from across the specialty
What's hot
January 1, 2020
In this monthly column, members of Dermatology World's Editorial Advisory Workgroup identify exciting news from across the specialty.
Is frontal fibrosing alopecia (FFA) really caused by sunscreen? A new JAAD article reviews the evidence. The rising incidence of FFA has sparked speculation over possible environmental triggers, especially sunscreen use. This initially gained press after a retrospective questionnaire reported higher rates of sunscreen use in patients with FFA as compared to controls. Since then, a growing number of studies linking FFA to sunscreen have sparked both interest and controversy in the dermatology community.
Several hypotheses exist as to how sunscreen might cause FFA: (1) sunscreen penetrates the hair follicle and elicits a lichenoid reaction (the dominant theory); (2) direct tissue damage due to oxidative stress may occur when titanium dioxide (a frequently used UV filter) is exposed to UV light; (3) frequent use of sunscreen may lead to endocrine disruption, and (4) sunscreen allows an inflammatory process to occur by blocking the immunomodulatory effects of UV light.
What is the evidence? The authors note that it is important to remember that the link between sunscreen and FFA is supported by only four questionnaire studies, each with limitations, such as recall bias. Thus, while it is possible that sunscreen could contribute to FFA in patients with predisposing factors (such as genetics), at this time we have insufficient evidence to recommend against sunscreen use to these patients.
Check out the full article.
Pathology report: “nonspecific changes in the skin.” What do you do when you receive a report like this? Can you trust that the biopsy is really not helpful? A recent article in the Journal of Cutaneous Pathology (2019. 46(12):905-12) discussed invisible dermatoses. This terminology generally refers to a clinically obvious skin rash with minimal changes on histopathology. In the study, 81 skin biopsies from a tertiary hospital were reviewed. They were all originally diagnosed by general pathologists as “minimal changes” or “no specific diagnosis.” The cases were then reviewed by a dermatopathologist. Of these 81 cases, 53% were found to have a specific diagnosis by the dermatopathologist and 47% remained nonspecific. Some examples of the specific diagnoses include vitiligo, pigmented purpura, macular amyloidosis, urticaria, and pityriasis versicolor. This study highlights the fact that the histopathology of skin rashes can be very subtle and difficult to interpret. It also reinforces the role of dermatopathologists, as well as the importance of providing adequate clinical information when submitting biopsies to the laboratory.
Management of a furuncle typically involves incision and drainage, bacterial culture and sensitivities, and an empiric, oral antibiotic. In a retrospective study (2011–2015), in an outpatient dermatology clinic, there were approximately 34,000 dermatology visits (J Am Acad Dermatol. 2019; 81(4): 1027-28).
Of these, about 400 visits included bacterial culturing. Abscesses (carbuncles, furuncle, and cysts) were the most common diagnoses that were being cultured for bacteria. The most commonly used empiric, oral antibiotic was doxycycline, which was prescribed to cover Staphylococcus species.
About 87% of bacterial cultures were positive. Of these, 45% were positive for Staphylococcus aureus or beta-hemolytic Streptococcus. Skin colonizers (coagulase-negative staphylococci) and skin contaminants grew in the other 55% of positive cultures. For bacterial cultures performed at the same time as incision, drainage, and empiric antibiotic therapy, change in management occurred in only 4.5% of cases. In 4.2% of positive bacterial cultures, the bacteria were resistant to empiric antibiotic therapy, but there were no subsequent changes in the antibiotic therapy. This small study shows that bacterial culturing of abscesses infrequently leads to changes in management. This study emphasizes the need to determine the best practices, while decreasing wasteful tests and unnecessary costs in health care.
The maxim primum non nocere — literally, “first, do no harm” — guides physicians in the practice of medicine. The public should take heed, too.
On Nov. 5, 2019, the Food and Drug Administration (FDA) updated a safety communication regarding biotin, a common ingredient in supplements marketed as promoting hair, skin, and nail health. Biotin deficiency can cause hair loss, rash, and brittle nails, among other problems. However, biotin deficiency is rare in the United States, meaning most consumers of biotin supplements do not benefit from them.
Additionally, there can be serious downsides. Because biotin binds with some proteins, it is used in laboratory immunoassays that test for levels of hormones and of markers of cardiac health. Excess biotin in patient samples can significantly skew some lab test results up or down, depending on the test.
The FDA’s recent safety communication specifically notes that biotin can falsely lower results for troponin, a biomarker used in diagnosing heart attacks. The risk is not just theoretical. According to the FDA, falsely low troponin test results in one patient taking biotin supplements led to that patient’s death. Of note, since the FDA’s initial safety communication on this topic in 2017, some troponin test manufacturers — but not all — have addressed the possibility that excess biotin might alter test results.
As dermatologists, we often encounter patients who are taking biotin supplements. When discussing with patients risks and benefits of biotin supplements, we should take the FDA’s safety communication — literally — to heart.
Read the FDA’s safety communication.
