Optical Coherence Tomography in the Evaluation of the Scalp and Hair: Common Features and Clinical Utility

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.

Research Techniques Made Simple: Emerging Imaging Technologies for Noninvasive Optical Biopsy of Human Skin

Over the past few years, high-resolution optical imaging technologies such as optical coherence tomography (OCT), reflectance confocal microscopy (RCM), and multiphoton microscopy (MPM) have advanced significantly as new methodologies for clinical research and for real-time detection, diagnosis, and therapy monitoring of skin diseases. Implementation of these technologies into clinical research and practice requires clinicians to have an understanding of their capabilities, benefits, and limitations. This concise review provides insights on the application of OCT, RCM, and MPM for clinical skin imaging through images acquired in vivo from the same lesions. The presented data are limited to pigmented lesions and basal cell carcinoma.

Update on trichoscopy: Integration of the terminology by systematic approach and a proposal of a diagnostic flowchart

Trichoscopy represents a non-invasive diagnostic modality widely used in daily practice. Despite the common perception that this technique has been fairly established, some key issues remain to be addressed. Complexity and inconsistency in terminology in past literature are likely to confuse investigators when they are recording, reporting, and retrieving the findings. In addition, a diagnostic algorithm adopting sufficiently integrated and updated findings is not readily available. By adopting a systematic review approach, this review attempted to redefine major trichoscopic findings and integrate their synonyms individually into the most frequently used terms besides identifying and discussing terms which potentially cause confusion. The findings are categorized into five subgroups: hair shaft, follicular, perifollicular, scalp findings, and hair distribution pattern abnormalities. The calculation of sensitivities and positive predictive values of such redefined findings was conducted by reviewing the descriptions in the past literature on major hair diseases, including alopecia areata, androgenetic alopecia/female pattern hair loss, telogen effluvium, trichotillomania, lichen planopilaris, frontal fibrosing alopecia, central centrifugal cicatricial alopecia, discoid lupus erythematosus, folliculitis decalvans, tinea capitis, and dissecting cellulitis, to confirm the diagnostically meaningful findings for representative diseases. This attempt redefined, for instance, yellow dots, short vellus hairs, exclamation mark hairs, black dots, and broken hairs as the findings of diagnostic significance for alopecia areata and hair diameter diversity, peripilar sign, and focal atrichia for androgenetic alopecia/female pattern hair loss. An updated diagnostic flowchart is proposed with the instructions to maximize its usefulness. Current limitations and future perspectives of trichoscopy as well as other emerging non-invasive diagnostic modalities for hair diseases are also discussed.

New Diagnostic Tools to Evaluate Hair Loss

The precise and reliable diagnosis of hair loss disorders is essential for developing a successful management plan. It is, thus, the responsibility of the dermatologist to select the appropriate diagnostic tools to effectively evaluate patients presenting with hair loss concerns. Fortunately, there is a growing body of noninvasive and invasive diagnostic resources, each with advantages and disadvantages. For the practicing dermatologist, tactile assessments and direct visualization are enhanced with scoring instruments, questionnaires, handheld trichoscopy, and scalp biopsy. For research and clinical study purposes, the more precise, high-resolution tools such as videodermoscopy, optical coherence tomography, and phototrichograms, may be useful.