Introduction:Classic monilethrix is an autosomal dominant hair shaft disorder caused by heterozygous mutations in hair keratin genes, leading to childhood-onset hair fragility and perifollicular hyperkeratosis, most prominent on the occipital scalp. Case Presentation:A 38-year-old woman with lifelong occipital hair fragility and inability to grow hair beyond short lengths presented with progressive frontal scalp thinning. Trichoscopy revealed hair shaft variability of numerous hair shafts, including miniaturized hairs showing alternating nodes and internodes consistent with monilethrix and androgenetic alopecia. Conclusion:This clinical case and review of the literature underlines that diagnosis and management of monilethrix can be more difficult when it is associated with other acquired hair conditions, such as androgenetic alopecia.

BACKGROUND:Herpes zoster (HZ) typically resolves without sequelae, but rare chronic dermatologic complications can develop at the site of prior infection, termed an isotopic response. This phenomenon involves the emergence of a new, unrelated skin disease in the area previously affected by HZ. OBJECTIVE:To describe 2 cases of autoimmune skin conditions, discoid lupus erythematosus (DLE) and bullous pemphigoid (BP), emerging as isotopic responses following HZ infection, and to discuss possible pathophysiologic mechanisms. CASES:Two patients with a history of HZ presented with persistent or recurrent cutaneous lesions localized to the previously affected dermatomes. Clinical evaluation, histopathology, immunologic testing, and PCR were performed to exclude viral persistence and con-firm autoimmune etiology.Case 1: A 51-year-old woman with systemic lupus erythematosus (SLE) developed chronic plaques in a dermatomal distribution six months after HZ. Histology confirmed DLE. Restarting systemic immunosuppression and topical corticosteroids led to clinical improve-ment.Case 2: A 65-year-old woman developed a chronic blistering eruption two years after HZ in the same location. Biopsy and immunofluo-rescence confirmed BP. She responded well to localized high-potency corticosteroid therapy. CONCLUSION:These cases underscore the diagnostic importance of recognizing Wolf's isotopic response, in which autoimmune skin conditions may manifest at sites of prior HZ. Clinicians should maintain a high index of suspicion for autoimmune etiologies in persis-tent post-HZ eruptions, especially in patients with underlying autoimmune diseases.

Botulinum toxin (BoNT) is well-recognized throughout dermatology for its cosmetic indications and growing therapeutic value. Recent studies have trialed BoNT in the treatment of hair and scalp disorders, many of which lack long-term effective treatments and significantly impact quality of life. In this review, we summarize the current clinical literature on this topic to comprehensively evaluate the efficacy, safety, and clinical value of BoNT in treating hair and scalp conditions. A literature search on PubMed/MEDLINE and Scopus identified 40 articles reporting the use of 25–200 units of BoNT-A or B in 689 patients with hair loss (79.5%), scalp seborrheic dermatitis/hyperseborrhea (10%), craniofacial hyperhidrosis (9%), folliculitis decalvans/dissecting folliculitis (0.86%), scalp pain (0.43%), or linear scleroderma (0.29%). Most studies on BoNT therapy for androgenetic alopecia (AGA) reported mild or non-significant hair growth; however, considerable variability in outcome measures complicates the ability to draw definitive conclusions or justify the use of BoNT over established AGA therapies. BoNT-A and B showed consistent efficacy in treating craniofacial hyperhidrosis with minimal side effects. Additional scalp conditions may benefit from BoNT therapy, but the evidence is limited, and larger, controlled studies are needed to better understand BoNT’s clinical value in these conditions.

Antiandrogen therapy is central to the management of androgenetic alopecia and is commonly achieved using 5-alpha-reductase inhibitors (finasteride, dutasteride) or steroidal antiandrogens (spironolactone). Bicalutamide, a peripherally selective antiandrogen, is FDA-approved for the treatment of metastatic prostate cancer and has recently demonstrated potential in treating female androgenetic alopecia pattern hair loss (FPHL). In this study, we systematically reviewed articles reporting the use of bicalutamide in patients with hair loss. Nine articles were identified that described bicalutamide as combination or monotherapy in 494 female patients; 476 diagnosed with FPHL (96%), 10 with persistent chemotherapy-induced alopecia (2%), 7 with fibrosing alopecia in a pattern distribution (1.4%), and 1 with central centrifugal cicatricial alopecia (0.2%). Reduction in hair loss severity was 17% to 28.9% in FPHL patients. Persistent chemotherapy-induced alopecia patients similarly demonstrated a statistically significant decrease in hair loss severity; however, fibrosing alopecia in a pattern distribution and central centrifugal cicatricial alopecia patients did not improve significantly. Adverse events were reported in 59 of 494 patients (11.9%). While this reported efficacy of bicalutamide in persistent chemotherapy-induced alopecia, fibrosing alopecia in a pattern distribution, and central centrifugal cicatricial alopecia is notably limited by small sample sizes and concomitant therapy, our study overall demonstrates the promising efficacy of bicalutamide in FPHL management, particularly when co-existing hyperandrogenic conditions (eg, polycystic ovarian syndrome) may complicate the effectiveness of other antiandrogen therapies.

Permanent drug-induced alopecia is rare; however, increasing cases are being reported. Non-inflammatory phenotypes include permanent/persistent alopecia after chemotherapy, mainly associated with taxanes and busulfan, and persistent alopecia after hedgehog pathway inhibitor therapy. Inflammatory phenotypes, associated with tyrosine kinase inhibitors and monoclonal antibodies, include folliculitis decalvans, lichen planopilaris, and erosive pustular dermatosis of the scalp. Evidence, however, is largely limited to case reports and lacks robust pathology results or long-term follow up studies. The purpose of this review is to provide an updated summary, using evidence-based data and clinical expertise, on the drugs associated with scarring or permanent/persistent alopecia along with their reported prevalence, clinical findings, and management strategies.

Androgenetic alopecia (AGA) is a non-scarring hair loss resulting from androgen-induced shortening of the hair follicle growth phase and eventual hair follicle miniaturization. Clinically, AGA manifests as a distinct hair loss pattern characterized as progressive hair thinning and shedding in androgen-dependent regions of the scalp. Given a pathogenesis centered around androgenic activity, any external stimulus that affects the delicate balance of androgens and estrogens has the potential to impact the clinical course of AGA. A number of drugs that promote androgenic activity or inhibit estrogenic activity carry the risk of unmasking AGA in genetically predisposed individuals or exacerbating existing AGA symptoms. A comprehensive understanding of the specific drugs that contribute to AGA progression and severity is essential in the effective clinical evaluation and management.

International Journal of DermatologyVolume 62, Issue 9 p. e489-e490 Correspondence Effects of oral minoxidil on nails: a cross-sectional analysis Waleed Alsalhi MD, Waleed Alsalhi MD Department of Dermatology, College of Medicine, Majmaah University, Al-Majmaah, Kingdom of Saudi ArabiaSearch for more papers by this authorBetty Nguyen BS, Corresponding Author Betty Nguyen BS [email protected] orcid.org/0000-0002-0402-3926 Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, USASearch for more papers by this authorBrian W. Morrison MD, Brian W. Morrison MD Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, USASearch for more papers by this authorEran C. Gwillim MD, Eran C. Gwillim MD Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, USASearch for more papers by this authorAntonella Tosti MD, Antonella Tosti MD Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, USASearch for more papers by this author Waleed Alsalhi MD, Waleed Alsalhi MD Department of Dermatology, College of Medicine, Majmaah University, Al-Majmaah, Kingdom of Saudi ArabiaSearch for more papers by this authorBetty Nguyen BS, Corresponding Author Betty Nguyen BS [email protected] orcid.org/0000-0002-0402-3926 Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, USASearch for more papers by this authorBrian W. Morrison MD, Brian W. Morrison MD Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, USASearch for more papers by this authorEran C. Gwillim MD, Eran C. Gwillim MD Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, USASearch for more papers by this authorAntonella Tosti MD, Antonella Tosti MD Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, USASearch for more papers by this author First published: 02 February 2023 https://doi.org/10.1111/ijd.16608Citations: 1 Conflict of interest: Antonella Tosti is an investigator for Eli Lilly, Pfizer, and Erchonia and a consultant for DS Laboratories, Monat Global, Almirall, Thirty Madison, Eli Lilly, Bristol Myers Squibb, P&G, Pfizer, and Myovant. The remaining authors have no conflicts to declare. Funding source: None. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References 1Randolph M, Tosti A. Oral minoxidil treatment for hair loss: a review of efficacy and safety. J Am Acad Dermatol. 2021; 84: 737–46. 10.1016/j.jaad.2020.06.1009 CASPubMedWeb of Science®Google Scholar 2Aiempanakit K, Geater A, Limtong P, Nicoletti K. The use of topical minoxidil to accelerate nail growth: a pilot study. Int J Dermatol. 2017; 56: 788–91. 10.1111/ijd.13620 CASPubMedWeb of Science®Google Scholar 3Garbers L, Miola AC, Dias PCR, Miot LDB, Miot HA, Schmitt JV. Efficacy of 2.5 mg oral biotin versus 5% topical minoxidil in increasing nail growth rate. Exp Dermatol. 2021; 30: 1322–3. 10.1111/exd.14316 CASPubMedWeb of Science®Google Scholar 4Geyer AS, Onumah N, Uyttendaele H, Scher RK. Modulation of linear nail growth to treat diseases of the nail. J Am Acad Dermatol. 2004; 50: 229–34. 10.1016/j.jaad.2003.07.011 PubMedWeb of Science®Google Scholar Citing Literature Volume62, Issue9September 2023Pages e489-e490 ReferencesRelatedInformation

BACKGROUND:Many reports have described the use of botulinum toxin (BTX) in the treatment of scalp conditions, but no studies have synthesized these collective findings.OBJECTIVE:We conducted a systematic review to summarize the scalp conditions for which treatment with BTX has been described.METHODS:We searched PubMed/MEDLINE and Scopus for articles in English published before November 1, 2022, using the keywords "hair" or "scalp" and BTX-related search terms. Articles that described patients who received injections of BTX for the management of scalp conditions were included.RESULTS:Twenty-four original articles (12 case reports, 9 clinical trials, and 3 case series) were identified that described 309 patients with a scalp condition treated with BTX. Androgenetic alopecia, craniofacial hyperhidrosis, and scalp hyperseborrhea had the most robust data supporting the clinical efficacy of BTX.CONCLUSION:The current quality of evidence is highly variable and, for many conditions, limited to small observational studies. Botulinum toxin may be a promising therapeutic option for patients with various scalp conditions, but future studies are needed to better understand its efficacy and safety.

Cannabinoid products have been studied in the treatment of various dermatologic conditions. We searched PubMed/MEDLINE for articles published before 1 February 2023 that described the use of cannabinoids in the management of hair, scalp, and skin conditions, identifying 18 original articles that encompassed 1090 patients who used various forms of cannabinoid products. Where specified, topical cannabidiol (CBD) was the most commonly utilized treatment (64.3%, 173/269), followed by oral dronabinol (14.4%, 39/269), oral lenabasum (14.1%, 38/269), and oral hempseed oil (5.9%, 16/269). Using the GRADE approach, we found moderate-quality evidence supporting the efficacy of cannabinoid products in managing atopic dermatitis, dermatomyositis, psoriasis, and systemic sclerosis and moderate-quality evidence supporting a lack of efficacy in treating trichotillomania. There was low to very low quality evidence supporting the efficacy of cannabinoid products in managing alopecia areata, epidermolysis bullosa, hyperhidrosis, seborrheic dermatitis, and pruritus. Our findings suggest that cannabinoids may have efficacy in managing symptoms of certain inflammatory dermatologic conditions. However, the evidence is still limited, and there is no standardized dosage or route of administration for these products. Large randomized controlled trials and further studies with standardized treatment regimens are necessary to better understand the safety and efficacy of cannabinoids.

Introduction: Teledermatology has been shown to improve efficiency and reduce barriers to care for patients. However, teledermatology is limited by the inability to perform diagnostic tests. With proper planning, teletrichoscopy can be utilized with teledermatology to evaluate patients with hair loss. Case Presentation: Diagnosis of this patient was made using images taken during the televisit, including scalp images taken by the patient using a handheld microscope and images of the hair roots taken by her referring doctor. Conclusion: Hair tests that can be conducted during teledermatology visits include a self-performed pull test, measurement of the thickness of the ponytail, measurement of the distance from the hairline to the glabella, and evaluation of the shedding scale. These tests, in addition to mobile applications for imaging or low-cost handheld microscopes, can be utilized to virtually evaluate patients with hair loss.

Concerns about alopecia areata (AA) occurring after coronavirus disease 2019 (COVID-19) infection and vaccination have recently emerged, but current data are sparse and mostly limited to case reports. We conducted an online questionnaire among patients with AA to better understand the relationship between AA and COVID-19. Members of AA online support groups (e.g. 'Alopecia areata, find a cure') on social media were invited to participate in a questionnaire. Individuals were eligible to participate if they had been diagnosed with AA and tested positive for COVID-19 or received at least one COVID-19 vaccination. This study was approved by the University of Miami Institutional Review Board. Of 214 members who were eligible and invited to participate, 152 (71.0%) members agreed to complete the questionnaire and 131 (61.2%) members (mean age 41.6 years, 87.8% female) returned a completed questionnaire (Table 1). Of 59 respondents who tested positive for COVID-19, 25 (42.4%) reported AA symptoms after infection: 60.0% (15/25) had a new diagnosis of AA, and 36.0% (9/25) experienced relapse of pre-existing AA (Table 2). Of 113 respondents who received at least one COVID-19 vaccination, 77 (68.1%) reported AA symptoms after vaccination: 50.6% (39/77) had a new diagnosis of AA, and 49.4% (38/77) experienced relapse of pre-existing AA. The three most commonly implicated vaccines were manufactured by Pfizer (65/109, 59.6%), Moderna (22/109, 20.2%) and Oxford-AstraZeneca (13/109, 11.9%). Where reported, more patients developed symptoms of AA after the second COVID-19 vaccination (25/47, 53.2%) than the first vaccination (12/47, 25.5%) or third vaccination (10/47, 21.3%). On average, symptoms of AA occurred 50.6 days after COVID-19 infection and 61.5 days after COVID-19 vaccination. Where reported, the most commonly utilized treatments at the time of questionnaire were corticosteroid injections (20/48, 41.7%), topical corticosteroids (18/48, 37.5%), topical or oral minoxidil (11/48, 22.9%), oral Janus kinase (JAK) inhibitors (5/48, 10.4%), oral corticosteroids (4/48, 8.3%) and topical JAK inhibitors (3/48, 6.3%) (Table 1). Collectively, our findings suggest that, while rare, symptoms of AA may develop after COVID-19 infection or vaccination in certain individuals. The mechanism of this potential association is unclear but may involve upregulation of pro-inflammatory cytokines such as interleukin (IL)-6, tumour necrosis factor (TNF)-α and IFN-ɣ that are also implicated in AA pathogenesis.1 Psychologic stress from the COVID-19 pandemic may also trigger or exacerbate AA.2 Despite increasing reports of AA after COVID-19 infection,3 one recent cohort study of 226,737 individuals concluded that diagnosis of COVID-19 was not significantly associated with development of AA.4 As of May 20, 2022, 143 cases of AA occurring after COVID-19 vaccination have been reported to the Center for Disease Control and Prevention's Vaccine Adverse Event Reporting System.5 Given this relatively small number of cases compared to the total vaccinated population, we believe that benefits of COVID-19 vaccination significantly outweigh potential risks. Our sentiment is shared by the National Alopecia Areata Foundation, which recommends that all AA patients with no known allergies to vaccine components receive the COVID-19 vaccine.6 Because our data are derived from patient-reported information from online support groups, our study has several limitations, including response and sampling bias. In addition, data on patient comorbidities and clinical outcomes were not collected, limiting conclusions that can be drawn from this data. Moreover, because AA is characterized by relapsing and remitting symptoms, reports of AA relapse after COVID-19 infection and vaccination may be coincidental in certain respondents. Further studies are needed to better understand the relationship between AA and COVID-19. None. Antonella Tosti is an investigator for Eli Lilly, Pfizer and Erchonia and a consultant for DS Laboratories, Monat Global, Almirall, Thirty Madison, Eli Lilly, Bristol Myers Squibb, P&G, Pfizer and Myovant. Betty Nguyen has no conflicts to declare. The data that support the findings of this study are available from the corresponding author upon reasonable request.

Background: Treatments for scarring alopecia are limited. Naltrexone, an opioid receptor antagonist, exhibits anti-inflammatory and analgesic effects at low doses of 1-5 mg daily and has been used off-label to manage numerous autoimmune and inflammatory conditions [1,2]. Data on the efficacy of low-dose oral naltrexone in treating scarring alopecia remains sparse [3,4]. We conducted a single-center retrospective chart review of patients taking low-dose oral naltrexone for scarring alopecia from January 2015 to April 2022. Adult patients with at least one follow-up visit documented were included. We identified 46 patients (mean age 55.7 years; 87.0% female); diagnoses included lichen planopilaris (63.0%, 29/46), frontal fibrosing alopecia (45.7%, 21/46), fibrosing alopecia in a pattern distribution (6.5%, 3/46), folliculitis decalvans (2.2%, 1/46), and central cicatricial centrifugal alopecia with traction alopecia (2.2%, 1/46). Efficacy was assessed by evaluating severity of scalp symptoms and presence of peripilar casts on trichoscopy. After treatment with naltrexone, 17.4% (8/46) reported improvement of their scalp symptoms of pruritis, pain, or scalp tenderness, and 28.3% (13/46) showed improvement of trichoscopic signs. Side effects were reported by 21.7% (10/46) of patients and included insomnia (70.0%, 7/10), vivid dreams (20.0%, 2/10), and gastrointestinal upset (10.0%, 1/10). Low-dose oral naltrexone decreases inflammation in a proportion of patients with scarring alopecia. Side effects are very mild compared with other systemic treatments and mainly involve sleep disturbances. Our study has several limitations, such as inclusion of participants on other concurrent treatments. Controlled studies are needed to better understand the clinical efficacy of oral naltrexone in scarring alopecia.

Dear Editor, TikTok, a videofocused social networking service with over 1 billion active monthly users, has been used to disseminate dermatologic information.1 Previous studies have found discrepancies in the quality of videos based on the credentials of the content creator using the DISCERN instrument, a 16item validated questionnaire that measures quality of consumer health information based on criteria including relevance, references, and treatment risks and benefits on a scale from 1 (poor) to 5 (excellent).2– 4 The primary aim of this study was to summarize diagnoses, content type, content creators and DISCERN scores of TikTok's most viewed alopeciarelated videos. We conducted a crosssectional, descriptive study to analyse the characteristics and reliability of the most viewed TikTok videos on alopecia areata, traction alopecia, trichotillomania, female and male pattern hair loss, alopecia universalis, telogen effluvium and frontal fibrosing alopecia. We conducted our search on 17 February 2022 and included the 25 most popular videos for each diagnosis, yielding 200 videos. NonEnglish videos, duplicates and advertisements were excluded, yielding 183 videos. We categorized the diagnosis, content type and content creator of all 183 videos (Table 1). Of videos categorized as ‘educational’, we further assessed their reliability and DISCERN scores (Table 2). Videos were deemed ‘reliable’ if they did not contain any information that conflicted with evidencebased guidelines. Two independent raters (B.N. and A.G.P.) assessed DISCERN scores. Identities of content creators were confirmed via biographic information on TikTok or other linked social media platforms; boardcertified dermatologists were confirmed through the AAD. Interrater reliability was assessed using Cohen κ. Statistical analysis was performed using twotailed ttests, and p < 0.05 was considered statistically significant. Patients produced 64.5% (118/183) of videos, while boardcertified dermatologists produced 9.8% (18/183; Table 1). About 54.6% (100/183) of videos were categorized as primarily depicting ‘personal experiences’, followed by 32.8% (60/183) that were considered primarily ‘educational’. Of these ‘educational’ videos, 70.0% (42/60) discussed treatments, 58.3% (35/60) aetiology, 15.0% (9/60) diagnosis and 8.3% (5/60) nutrition (Table 2). All videos posted by physicians (26/26) were considered ‘reliable’, compared with 56% (19/34) of videos posted by nonphysicians. Boardcertified dermatologists DOI: 10.1111/jdv.18500

Dermatologic TherapyVolume 35, Issue 8 e15605 LETTER Oral N-acetylcysteine in the treatment of Onychotillomania Betty Nguyen, Corresponding Author Betty Nguyen [email protected] Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA University of California Riverside School of Medicine, Riverside, California, USA Correspondence Betty Nguyen, Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, 1150 Northwest 14th Street, Miami, FL33136, USA. Email: [email protected]Search for more papers by this authorAhmed A. Hawash, Ahmed A. Hawash Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USASearch for more papers by this authorAntonella Tosti, Antonella Tosti Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USASearch for more papers by this author Betty Nguyen, Corresponding Author Betty Nguyen [email protected] Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USA University of California Riverside School of Medicine, Riverside, California, USA Correspondence Betty Nguyen, Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, 1150 Northwest 14th Street, Miami, FL33136, USA. Email: [email protected]Search for more papers by this authorAhmed A. Hawash, Ahmed A. Hawash Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USASearch for more papers by this authorAntonella Tosti, Antonella Tosti Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida, USASearch for more papers by this author First published: 27 May 2022 https://doi.org/10.1111/dth.15605Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume35, Issue8August 2022e15605 RelatedInformation

Dear Editor, Lichen planus (LP) has been reported after exposure to medications, viral infections and vaccinations.1 Though not precisely known, the prevalence of oral2 and cutaneous3,4 LP is estimated to be less than 1.3% and 0.5% of the general population, respectively. Recently, there have been increasing reports of LP occurring after coronavirus disease 2019 (COVID19) infection and vaccination, but no studies have analysed the aggregate data to date. In this study, we systematically review LP after COVID19 infection and vaccination. A PubMed/MEDLINE search was conducted for articles containing the search terms ‘lichen planus’ and ‘COVID19’ published between 12 December 2019 and 31 May 2022, yielding 56 articles. Screening and review of articles were completed according to Preferred Reporting Items for Systematic and MetaAnalysis (PRISMA) guidelines. Two independent reviewers (B.N. and A.G.P.) screened titles, abstracts, and full texts for duplicates and relevance; 25 articles describing 26 patients (mean age 55.3 years, 65.4% female) who developed LP after COVID19 infection or vaccination were included (Table 1). Most LP cases occurred after COVID19 vaccination (22/26, 84.6%) rather than COVID19 infection (4/26, 15.4%) (Table 2). Most patients experienced a new diagnosis of LP (21/26, 80.8%) rather than an exacerbation or recurrence of preexisting disease (5/26, 19.2%). Of the 4 patients who developed LP after COVID19 infection, all experienced new onset (rather than exacerbation or relapse) of LP. Of the 5 patients who had an exacerbation or recurrence of LP, all received the COVID19 vaccination. Of the 22 patients who developed LP after COVID19 vaccination, the most commonly implicated vaccines were manufactured by Pfizer (10/22, 45.5%), OxfordAstraZeneca (7/22, 31.8%), Sinopharm (2/22, 9.1%), Johnson & Johnson (1/22, 4.5%) and Moderna (1/22, 4.5%). Symptoms of LP occurred an average of 13.4 days after COVID19 infection or vaccination. Our findings suggest that both COVID19 infection and vaccination may be correlated with development of LP. In a large retrospective cohort study, 0.067% (146/217,863) of patients developed oral lichenoid lesions or oral LP after COVID19 vaccination, compared to 0.027% (59/217,863) of unvaccinated controls (relative risk 2.475, p < 0.001).5 Although we found more patients who developed lichen planus after COVID19 vaccination compared to infection, our review has limitations, including reporting bias, and we feel that it is unlikely that vaccine components pose significant additional risks to patients. Because LP has been reported regardless of the active agents used in different COVID19 vaccines (e.g. mRNA lipid nanoparticles, adenovirus vectors and inactivated SARSCoV2), development of LP may be related to presentation of the SARSCoV2 spike protein to the immune system rather than individual vaccine components.5 Both COVID19 infection and vaccination have been shown to upregulate some of the same cytokines (e.g. tumour necrosis factor (TNF)α, interferon (IFN)ɣ, interleukin (IL)6) implicated in LP pathogenesis.6– 8 Given the small number of affected patients in our review, we hesitate to draw further conclusions from our data. We believe that benefits of COVID19 vaccination significantly outweigh potential risks, particularly because LP is rare and can be treated. Where reported, some patients in our study had partial or full resolution after 4 weeks of treatment. As it would be unusual for LP to improve after 4 weeks, some cases reported as LP may have been lichenoid reactions to COVID19 infection or vaccination. Further monitoring and studies are needed to better understand the relationship between lichen planus and COVID19 infection and vaccination.

Introduction:Scalp micropigmentation is a method of concealing alopecia by depositing permanent pigment in a tattoo-like manner. Pigment is deposited between hair follicles in a stippling pattern that resembles closely cut hair.Case Presentation:On trichoscopy, characteristic findings of scalp micropigmentation include homogenous, grey to black circular dots that are evenly spaced and appear larger than adjacent hair follicles. Findings were correlated with histopathology.Conclusion:Trichoscopy is a useful tool to visualize scalp micropigmentation in place of invasive procedures.