Recent Advances in Understanding of the Etiopathogenesis, Diagnosis, and Management of Hair Loss Diseases.

Hair-loss diseases comprise heterogenous conditions with respective pathophysiology and clinicopathological characteristics. Major breakthroughs in hair follicle biology and immunology have led to the elucidation of etiopathogenesis of non-scarring alopecia (e.g., alopecia areata, AA) and cicatricial alopecia (e.g., lichen planopilaris, LPP). High-throughput genetic analyses revealed molecular mechanism underlying the disease susceptibility of hair loss conditions, such as androgenetic alopecia (AGA) and female pattern hair loss (FPHL). Hair loss attracted public interest during the COVID-19 pandemic. The knowledge of hair loss diseases is robustly expanding and thus requires timely updates. In this review, the diagnostic and measurement methodologies applied to hair loss diseases are updated. Of note, novel criteria and classification/scoring systems published in the last decade are reviewed, highlighting their advantages over conventional ones. Emerging diagnostic techniques are itemized with clinical pearls enabling efficient utilization. Recent advances in understanding the etiopathogenesis and management for representative hair diseases, namely AGA, FPHL, AA, and major primary cicatricial alopecia, including LPP, are comprehensively summarized, focusing on causative factors, genetic predisposition, new disease entity, and novel therapeutic options. Lastly, the association between COVID-19 and hair loss is discussed to delineate telogen effluvium as the predominating pathomechanism accounting for this sequela.

Management of hair loss after severe acute respiratory syndrome coronavirus 2 infection: Insight into the pathophysiology with implication for better management.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was declared a pandemic by the World Health Organization, and COVID-19 continues to have a major impact on society. Numerous studies have reported impaired health sequelae after COVID-19 recovery, one of which is hair loss. Individuals with hair loss experience a substantial mental burden, which potentially hinders their social life. However, few studies have systematically analyzed the details including hair loss. Therefore, we conducted a narrative review using PubMed on the frequency, associated comorbidities, disease characteristics, and treatment of hair loss after SARS-CoV-2 infection (HLASCI). Two search strings were used to identify 28 articles. Of note, most of the literature identified on COVID-19 sequelae reported an emergence/occurrence of hair loss. HLASCI is speculated to be composed of a heterogeneous population, with the onset or exacerbation of telogen effluvium (TE), anagen effluvium, androgenetic alopecia (AGA), and alopecia areata (AA) reported as possible underlying mechanisms. Among these, acute TE is thought to be the primary cause of HLASCI, with COVID-19 treatment and TE improvement being considered crucial for HLASCI management. An association between COVID-19 and AA exacerbation has also been implicated with still insufficient evidence. Spontaneous recovery of TE can be expected once infection reduces; however, faster improvement in symptoms is expected to reduce the mental and social burden of patients. An additional search string identified 11 articles about TE treatment which suggested that the use of minoxidil may be beneficial. Topical minoxidil has been widely used for AGA patients, who have been speculated to exhibit poor resistance to SARS-CoV-2. Topical minoxidil may provide relief from HLASCI, but future clinical research is warranted to confirm this observation.