Lichenoid vulvar disease: A review

Biopsy-verified vulvar lichen sclerosus: Incidence trends 1997-2022 and increased risk of vulvar squamous precancer and squamous cell carcinoma

Population-based data on the epidemiology of vulvar lichen sclerosus (LS) are sparse and only few prospective studies have investigated the malignant potential of the disease. We used the nationwide Danish Pathology Registry to first assess the incidence of biopsy-verified vulvar LS in the period 1997-2022 and second to examine the incidence of vulvar high-grade squamous precancer and squamous cell carcinoma (SCC) in women with biopsy-verified vulvar LS (1978-2019) compared with that expected in the general female population. For the latter aim, we computed standardized incidence ratios (SIRs) with 95% confidence intervals (CIs). During our study period, the age-standardized incidence rate of vulvar LS increased from 5.0 (1997-1998) to 35.7 (2021-2022) per 100,000 person-years. Compared with the general female population, women with biopsy-verified vulvar LS had significantly increased rates of vulvar high-grade squamous precancer (SIR = 8.5; 95% CI: 7.2-10.0) and SCC (SIR = 16.2; 95% CI: 14.2-18.4). The SIRs of vulvar high-grade squamous precancer and SCC did not vary substantially according to length of follow-up. This nationwide and population-based study shows a 7-fold increase in the incidence of biopsy-verified vulvar LS since 1997. Data also show that women with biopsy-verified vulvar LS have 8.5 and 16 times higher than expected incidence of vulvar high-grade squamous precancer and SCC, respectively. The substantially increased incidence of vulvar high-grade squamous precancer and SCC following LS is important in relation to the clinical management and follow-up of LS patients.

Vulvar Lichenoid Dermatoses With Emphasis on the Distinction Between Lichen Sclerosus and Lichen Planus: A 10-Year Study

OBJECTIVES

Lichen planus (LP) and lichen sclerosus (LS) are the most common vulvar lichenoid dermatoses. The diagnostic challenges are due to site-specific variation in microscopic appearance and small-sized biopsies. Authentication of diagnostic criteria to distinguish LS and LP to uncover any resemblance or divergence in presentation of these conditions is attempted.

METHODS

Cases of vulvar LP and LS diagnosed between January 2012 to December 2022 were included. The clinical details included age, presenting symptoms, examination findings, and other organ involvement. Histopathological analysis of epidermal, dermal, and adnexal findings was done.

RESULTS

There were 28 cases of vulvar LP and 72 cases of LS, with a median age of 51 and 60 years, respectively. Depigmentation and atrophy were the major clinical features in LS, whereas ulcers/erosions and erythema were more prevalent in LP with a significantly higher incidence of oral involvement. The most diagnostic feature in LS was diffuse dermal sclerosis (76.8%) and interstitial pattern of inflammation (81.4%), whereas the characteristic features in LP cases was a lichenoid pattern of inflammation (85.7%), necrotic keratinocytes, and lymphocytic exocytosis. In 44.4% of LS, unconventional features like compact orthokeratosis, parakeratosis, thickened/wedge-shaped hypergranulosis, and sawtooth rete pegs were noted. Lichen sclerosus with lichenoid inflammation (21.4%) mimicked LP, from which it was distinguished by presence of thickened or diminished granular layer with basal melanin absence (60%) and dermal homogenization (80%).

CONCLUSION

Although the classical, well-established variant of LS poses no diagnostic difficulty, the unconventional variant may mimic LP. Identification of the subtle histological clues demonstrated in this study can help to arrive at the correct diagnosis.

Advances in the pathogenesis of vulvar lichen sclerosus

Vulvar lichen sclerosus (VLS) is a chronic non-neoplastic skin lesion characterized by vulvar itching, pain, atrophy, whitening of the skin and mucous membranes, and gradual atrophy and disappearance of the labia minora, which can eventually lead to vulvar scarring, causing functional impairment and seriously affecting the patient's physical and mental health. VLS can occur at any age, however, its pathogenesis and etiology are not fully understood. Considerable progress has been made in related research on genetic susceptibility factors, autoimmune disorders, collagen metabolism abnormalities, and their triggering factors in disease formation and progression. This article reviews the etiology of vulvar lichen sclerosus.

A large sample-based case-control study of related risk factors of two types of lichenoid vulvar disease (LVD)

PURPOSE

The purpose of this study is to identify the associated factors of two types of lichenoid vulvar disease (LVD) and to compare the differences in related factors between the different pathological types of lichenoid vulvar disease (LVD).

METHODS

The study conducted at the West China second Hospital of Sichuan University included a total of 1770 patients with biopsy-confirmed vulvar lichen simplex chronicus (VLSC)and vulvar lichen sclerosus(VLS), along with 1209 patients with normal vulvovagina as control. Further pathological subtype analysis was carried out on 163 cases of vulvar lichen simplex chronicus and 51 cases of vulvar lichen sclerosus. In addition, Univariate chi-square test and multivariate logistic regression were used to analyze the lichenoid vulvar disease group and vulvovaginal normal control group.

RESULTS

Univariate analysis revealed that there were statistically significant differences (P < 0.05) in factors between the LVD group and the control group, except for living type, sleep habit, history of drinking, and allergic diseases. There was no significant difference in late sleep, spicy diet, and coffee intake in the factors of life and eating habits and the concomitant disease factors. Furthermore, univariate analysis showed that except for eating seafood, humid living environment, residence, caffeinated drinks, hypertension, and vaginitis, there were statistical differences in the related factors of LVSC.

CONCLUSION

The incidence about lichenoid vulvar disease is influenced by various factors such as dietary habits, living environment, mental stress, concomitant diseases, hormone levels and so on, and there were no significant differences in these factors between VLS and VLSC except for income, work stress, systemic immune diseases, and menopause.

Clinical study on multi-focused laser in the treatment of vulvar lichen sclerosus

Objective

To investigate the clinical effect of Multi-focused (MF) laser in the treatment of vulvar lichen sclerosus (VLS).

Methods

In this single-center, randomized controlled trial, we compared the effect of fractionated MF laser with other treatments on patients with biopsy-proven VLS. Patients with VLS were enrolled in this study and randomly divided into three groups. Patients in the experimental group were treated with a CO2 laser, control group 1 was treated with radiofrequency, and control group 2 was treated topically with glucocorticoids and soaking with Chinese patent medicine. The pruritus degree, skin elasticity, skin color, lesion scope, and total score were compared before treatment, at one month after treatment, and three months after treatment.

Results

One month after treatment, the pruritus degree, skin elasticity, skin color, lesion scope, and total score decreased in the experimental group, and the differences were statistically significant (P &lt; 0.05). In control group 1, the differences in pruritus degree, skin color, and total score were statistically significant (P &lt; 0.05), but the differences in skin elasticity and lesion scope were not statistically significant (P &gt; 0.05). In control group 2, the differences in pruritus degree and total score were statistically significant (P &lt; 0.05), but the differences in skin elasticity, skin color, and lesion scope were not statistically significant (P &gt; 0.05). At one month after the end of treatment, the differences in pruritus degree, skin elasticity, skin color, lesion scope, and total score among the three groups were not statistically significant. At three months after the end of treatment, the differences in the scores of the five indicators were statistically significant.

Conclusion

For the three treatment methods for VLS, topical corticosteroids + traditional Chinese medicine can quickly relieve itching symptoms in patients, but it cannot significantly improve skin elasticity, skin color, and lesion scope, and VLS easily relapses after treatment. Radiofrequency can improve itching symptoms and skin color but has poor effects on the change of skin elasticity and lesion scope. Multi-focused laser treatment can alleviate the degree of pruritus, improve skin color and elasticity, and narrow the lesion scope, and VLS will not relapse within three months after treatment.

Analysis of the Vulvar Skin Microbiota in Asymptomatic Women and Patients With Vulvar Lichen Sclerosus Based on 16S rRNA Sequencing

Vulvar lichen sclerosus (VLS) is a chronic inflammatory skin disease that brings life-long and psychological distress to patients. It remains unclear whether this condition is related to changes in the skin microbial community. The aim of this study was to evaluate the compositional characteristics of the vulvar skin microbiota between VLS patients and asymptomatic postmenopausal women. We included 60 cases of postmenopausal patients in the outpatient vulvar clinic of Peking University First Hospital from August 2020 to October 2020. Thirty-one patients were diagnosed with VLS by vulvar skin biopsy (VLS group), while 29 women were asymptomatic volunteers (control group). DNA was extracted from vulvar skin swabs of the VLS and control groups. The V3-V4 fragments of 16S rRNA were targeted for high-throughput sequencing and gene sequence analysis. The sequencing results were analysed by α diversity, β diversity, species composition, LEfSe analysis to compare the compositional differences of the vulvar skin microbiota between the two groups. Our study revealed that at the phylum level, patients with VLS had a lower relative abundance of Firmicutes (p < 0.0001) and a higher relative abundance of Proteobacteria than the control group (p < 0.0001). At the genus level, Lactobacillus spp. accounted for the largest proportion of the microflora in the asymptomatic controls, while the proportion of Prevotella spp. in the VLS group was the highest. In the VLS group, the relative abundance of Finegoldia spp., Ralstonia spp., Peptoniphilus spp., Anaerococcus spp., Campylobacter spp., Providencia spp. Kelbsiella spp., Ezakiella spp., and Escherichia-Shigella spp. was significantly increased compared with the control group. Although there was no significant difference in the α diversity of the vulvar skin microbiota, the β diversity differed significantly between the two groups.

Benign "lumps and bumps" of the vulva: A review

Vulvar dermatology represents a challenge for many providers. Given that the vulva is both a gynecologic and dermatologic organ, patients with cutaneous lesions involving the vulva may present to primary care, gynecology, or dermatology. Particularly within dermatology, the vulva remains understudied, which can lead to anxiety among providers regarding appropriate next steps in the diagnosis and management of vulvar lesions. Thus, the purpose of this review is to highlight commonly encountered anatomic variants and benign neoplasms of the vulva, distinguish them from key pathologic mimickers, and provide guidance to practicing dermatologists on what may constitute normal vulvar variations.

Fractional CO2 laser treatment as adjunctive therapy to topical steroids for managing vulvar lichen sclerosus

Objectives

Uncontrolled vulvar lichen sclerosus (VLS) is often associated with distressful symptoms of genital itch, irritation, and pain and can lead to a pathological process including anatomical changes, scarring, and an elevated risk of cancer in the genital area. First‐line topical corticosteroid as monotherapy is frequently not adequate to fully suppress disease activity and control symptoms. This study evaluated the efficacy of fractional CO₂ laser treatments as adjunctive therapy where recalcitrant VLS had been improved, but not adequately controlled, with topical corticosteroid treatment. Outcomes were evaluated up to 12 months after a series of CO₂ laser treatments delivered via a fractional handpiece.

Materials and Methods

Women with a diagnosis of VLS supported by histologic findings on biopsy and/or clinical signs on physical examination received up to five monthly laser treatments. Subjects maintained existing topical corticosteroid and any exogenous hormone treatment during the study. Investigators assessed severity (0 = not present, 1 = mild, 2 = moderate, or 3 = severe) of clinical signs and architectural changes present before adjunctive study interventions and at follow‐up visits. Subjects reported the presence of clinical symptoms and impact on quality of life on 4‐ or 5‐point Likert scales. The validated Female Sexual Function Index (FSFI) was used to assess changes in sexual function. Four subjects were biopsied before adjunctive laser treatment and at follow‐up.

Results

Twelve females, 11 postmenopausal, with a mean age of 57 ± 10 years received three to five monthly CO₂ laser treatments. Significant improvement in all prominent clinical signs and architectural changes were reported at the 3‐ and 6‐month follow‐ups after the treatment series. Significant improvement was maintained at the 12‐month follow‐up, with 89% of subjects showing at least one‐point improvement in elasticity compared to baseline; 86% in lichenification; 88% in sclerosis; and 80% in whitening and parchment‐like skin. Labial fusion and the extent of disease improved in 50% of patients. Ulcerations present in three subjects at baseline resolved after treatment. Subjects reported 86% improvement in dyspareunia and 83% in skin tearing. Quality of life improved significantly after treatment (p < 0.01). The 6‐month follow‐up FSFI showed significant improvement in sexual function compared to baseline (p < 0.05), with a mean point improvement of 4.5. Histology findings after treatment showed some positive improvement, as a decrease in dermal hyalinized zone thickness. There were no treatment complications or adverse events related to the treatment.

Conclusions

Fractional CO₂ laser treatment outcomes showed improvement in predominant clinical signs and architectural changes in VLS recalcitrant to topical corticosteroid treatment. Adjunctive laser treatment relieved symptoms and improved quality of life as well as sexual function. Fractional CO₂ laser treatment may provide an advanced treatment modality for the management of recalcitrant VLS with improved patient care and sustainable outcomes. Further study in a larger population and with CO₂ laser treatment to both vulvar tissue and the vaginal canal should be explored.

Efficacy and Safety of Liquid Nitrogen Cryotherapy for Lichen Simplex Chronicus: A Meta-Analysis

BACKGROUND

Lichen simplex chronicus (LSC) is characterized by localized lichenification and intense itching. It has been reported that the added use of liquid nitrogen cryotherapy (LNC) for LSC has significant efficacy and notable safety. Therefore, we conducted a meta-analysis based on existing randomized controlled trials (RCTs).

METHOD

We searched RCTs on LNC for LSC published up to August 2020 using various databases, including PubMed, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials, China Network Knowledge Infrastructure (CNKI), Chinese Biomedicine (CBM), Chinese Scientific Journals Database (VIP), and WanFang Database. Other studies were manually identified using the references cited in reviews. We applied fixed- or random-effects models, and all analyses were performed using Review Manager 5.4 software.

RESULTS

Twelve RCTs involving 1,066 participants provided eligible data for the meta-analysis. Based on the clinical effective rate, LNC treatment of LSC (risk ratio, RR 1.25, p = 0.005, I2 = 82%) was superior to controls. Subgroup analysis showed that the use of LNC alone (RR 1.04, I2 = 95%, p > 0.05) is not more effective than other therapies in the treatment of LSC, but the addition of LNC to the existing treatment increases the total clinical efficacy. Furthermore, the combined effect of LNC and topical medication (RR 1.39, I2 = 0%, p < 0.0001) was better than that of LNC and oral medication (RR 1.30, I2 = 0%, p < 0.00001). Greater frequency of LNC treatment did not improve the efficacy (thrice a week: RR 1.39 [1.21, 1.60]; twice a week: RR 1.27; once every 2 weeks: RR 1.32). Data from 6 RCTs with 508 participants showed no significant difference in AEs (p = 0.31) associated with added LNC treatment.

CONCLUSION

The addition of LNC (applying a cotton swab soaked with liquid nitrogen to wipe the lesion for approximately 10 s each time) to topical ointments, is effective and safe in the treatment of LSC. Increasing the treatment frequency of LNC did not necessarily improve the efficacy.

Vulvar Pruritus: A Review of Clinical Associations, Pathophysiology and Therapeutic Management

Vulvar pruritus is an unpleasant sensation and frequent symptom associated with many dermatologic conditions, including infectious, inflammatory and neoplastic dermatoses affecting the female genitalia. It can lead to serious impairment of quality of life, impacting sexual function, relationships, sleep and self-esteem. In this review, common conditions associated with vulvar itch are discussed including atopic and contact dermatitis, lichen sclerosus, psoriasis and infectious vulvovaginitis. We review the potential physiologic, environmental and infectious factors that contribute to the development of vulvar itch and emphasize the importance of addressing their complex interplay when managing this disruptive and challenging symptom.

The prevalence of self-reported medical comorbidities in patients with vulvar lichen sclerosus: A single-center retrospective study

OBJECTIVE

To compare the demographics and self-reported medical comorbidities of patients with vulvar lichen sclerosus (VLS) with those of women with other vulvar conditions.

METHODS

Intake questionnaires for patients presenting to the University of Michigan Center for Vulvar Diseases between 1996 and 2019 were entered into a de-identified database (n = 1983). Responses to questions about thyroid disease, urinary symptoms and signs, gastrointestinal conditions, and pain conditions were collected.

RESULTS

A total of 1983 women, including 865 patients with VLS and 1118 patients without VLS were enrolled. Pearson's χ² analysis showed that age, hypertension, anorectal fissures, peptic ulcer disease/gastroesophageal reflux disease, urinary incontinence, fibromyalgia, thyroid disease, kidney problems, liver problems, and cancer were significantly associated with VLS when compared between the VLS and non-VLS groups (P < 0.01). However, multiple regression analysis demonstrated that only age, thyroid disease, and anorectal fissures were strongly associated with VLS (P < 0.01).

CONCLUSION

Increasing age, thyroid disease, and anorectal fissures were significantly associated with VLS. The association between anorectal fissures and VLS likely represents a sequela of the disease rather than a true comorbidity.

Putative precancerous lesions of vulvar squamous cell carcinoma

Precursor lesions of vulvar squamous cell carcinoma (VSCC) can be divided into two major biologic and prognostic groups: HPV-associated and HPV-independent VSCC. These two pathways are categorized as usual vulvar intraepithelial neoplasia (uVIN) with progression to basaloid or warty VSCC and differentiated vulvar intraepithelial neoplasia (dVIN) with progression to the more common keratinizing VSCC. While the HPV-dependent pathway to squamous cell carcinoma is well-understood, the development of squamous cell carcinoma from HPV-independent lesions is less clear. The majority of HPV-independent lesions fall into the dVIN category, and mutations in TP53 have been implicated as the driver behind their development. Other less common HPV-independent precursor lesions, termed differentiated exophytic vulvar intraepithelial lesion (DEVIL) and vulvar acanthosis with altered differentiation (VAAD), have also been characterized as precursors to keratinizing and verrucous VSCC. Inflammatory conditions of the vulva such as lichen sclerosus and lichen simplex chronicus also put patients at risk for developing VSCC. We herein evaluate the available evidence and biologic basis for these VSCC precursor lesions, among other speculated entities, and discuss their clinical, diagnostic, and prognostic features.

Therapeutic Effects of Focused Ultrasound on Expression of Notch1, C-Fos and Transforming Growth Factor-β3 in Vulvar Skin of SD Rats with Vulvar Lichen Simplex Chronicus

The purpose of this study was to investigate the therapeutic effects of focused ultrasound on the expression of notch1, c-fos and transforming growth factor-β3 (TGF-β3) in genital skin of SD rats with vulvar lichen simplex chronicus (LSC). Fifty-six female SD rats with LSC were randomly divided into therapy and sham groups. The therapy group was exposed to focused ultrasound. The sham group received the same therapy with an instrument that had no power output. Four wk after a singly focused ultrasound therapy, histologic analyses revealed that recovered SD rats accounted for 75% of SD rats in the therapy group and 10.7% in the sham group. Total collagen fiber density in the superficial layer of dermis in the therapy group was significantly lower than that in the sham group. Notch1 and c-fos protein expression in the therapy group was significantly lower than that in the sham group, with the opposite effect present for TGF-β3. Focused ultrasound therapy may inhibit superficial collagen fibrosis in the dermis by affecting expression of notch1, c-fos and TGF-β3 in vulvar skin tissue and consequently reduce the recurrence rate of LSC.

Forming diagnostic criteria for vulvar lichen planus

BACKGROUND/OBJECTIVES

Vulvar lichen planus is a debilitating skin condition usually complicated by delayed diagnosis due to its highly variable clinical appearance and inconsistent histopathological characteristics. This study aims to devise a clinical diagnostic tool for the disease and to correlate this with histopathology findings.

METHODS

The retrospective single-centre chart review was conducted for patients presenting between January 2010 and December 2019. Clinical features were compared between 243 women with clinically suspected vulvar lichen planus with available histopathology, 50 patients with biopsy-proven vulvar lichen sclerosus and 50 patients with culture-proven chronic vulvovaginal candidiasis. Features which significantly differentiated between conditions were further studied using multivariate nonlinear regression analyses to formulate a score-based diagnostic criteria. Criteria was then applied to the remaining patients with inconclusive biopsies (classified as 'normal', 'non-specific' or 'suggestive or lichenoid') to determine sensitivity and specificity.

RESULTS

The clinical features that significantly differentiated the conditions were the presence of erosions (P < 0.001), glazed erythema (P < 0.001), oral involvement (P < 0.001), pain/burning sensation (P < 0.001) and hyperkeratotic border (P < 0.001). A score ≥2 correlated with a histopathological diagnosis of vulvar lichen planus with a sensitivity of 100%. The specificity was 92% and 88% when compared against vulvar lichen sclerosus and chronic vulvovaginal candidiasis, respectively. Sensitivity was 97%, 97% and 93% in suggestive, nonspecific and normal histopathological subgroups, respectively.

CONCLUSIONS AND RELEVANCE

The proposed criteria may aid clinicians in diagnosing patients if histopathology is inconclusive. Nonspecific and suggestive findings on biopsy for patients with ≥2 features on diagnostic criteria are comparable to a conclusive biopsy.

Erosive Vulvovaginitis Associated With Borrelia burgdorferi Infection

We describe a case of acute erosive vulvovaginitis accompanying Borrelia burgdorferi infection. The patient is a 57-year-old woman previously diagnosed with Lyme disease who presented with a painful erosive genital lesion. At the time of the outbreak, she was being treated with oral antibiotics, and she tested serologically positive for B burgdorferi and serologically negative for syphilis. Histological examination of biopsy tissue from the lesion was not characteristic of dermatopathological patterns typical of erosive vulvar conditions. Dieterle-stained biopsy sections revealed visible spirochetes throughout the stratum spinosum and stratum basale, and anti–B burgdorferi immunostaining was positive. Motile spirochetes were observed by darkfield microscopy and cultured in Barbour-Stoner-Kelly–complete medium inoculated with skin scrapings from the lesion. Cultured spirochetes were identified genetically as B burgdorferi sensu stricto by polymerase chain reaction, while polymerase chain reaction amplification of treponemal gene targets was negative. The condition resolved after treatment with additional systemic antibiotic therapy and topical antibiotics. In cases of genital ulceration that have no identifiable etiology, the possibility of B burgdorferi spirochetal infection should be considered.

Hypertrophic lichen planus of the vulva - A missed diagnosis

Lichen planus (LP) is an inflammatory dermatosis which can affect the skin, nails, and all mucous membranes, including the genitalia. Lichen planus on vulvar keratinized skin can manifest with diverse clinical features, probably due to higher temperature, PH, humidity, and bacterial flora which may modify typical cutaneous features. While lichen planus (LP) may affect the vulva in isolation, it may also be part of generalized outbreak in up to 20% cases. Herein, a case of a 53 year-old female who presented with a severely pruritic plaque over labia majora Since 6 -7 months, with no response to potent topical corticosteroids is reported. Provisional diagnosis of lichen simplex chronicus was considered however, histopathology was suggestive of hypertrophic lichen planus.

[Focused ultrasound therapy for reducing recurrence of vulvar lichen simplex chronicus in rats: efficacy and mechanism]

OBJECTIVE

To explore the changes of collagen fibrosis in the vulva skin of SD rats with lichen simplex chronicus (LSC) after focused ultrasound therapy and explore the mechanism by which focused ultrasound reduces the recurrence of vulvar LSC.

METHODS

Fifty female SD rat models of vulvar LSC were established and randomly divided into the treatment group and the control group (n=25) for treatment with focused ultrasound and sham treatment, respectively. Before and after the treatment, vulvar skin tissues were sampled to observe the pathological changes with HE staining and assess the density of collagen fibers using Masson staining. The ultrastructure of the collagen fibers in the superficial dermis was observed using transmission electron microscopy. The expressions of notch1 and c-fos in the vulvar tissue were detected by immunohistochemistry and Western blotting.

RESULTS

After 4 weeks of focused ultrasound therapy, 16% (4/25) of the rats in the treatment group showed lesion progression to LSIL, 4% (1/25) still had LSC, and 80% (20/25) showed normal vulvar skin. In the control group, progression to LSIL occurred in 19 (76%) rats, 3 (12%) rats still showed LSC, and only 3 (12%) had normal vulvar skin. The difference in the cure rate differed significantly between the two groups (P < 0.05). The density of collagen fibers in the superficial dermis and the expressions of notch1 and c-fos in the vulvar skin were significantly lower in the treatment group than in the control group (P < 0.05).

CONCLUSIONS

Focused ultrasound therapy can inhibit superficial collagen fibrosis of the dermis by lowering the expressions of notch1 and c-fos in the vulvar skin to reduce the recurrence of vulvar LSC in rats.

Lichen planus and lichenoid dermatoses: Clinical overview and molecular basis

Deriving from the Greek word λειχήν for "tree moss" and the Latin word planus for "planar," lichen planus is a relatively uncommon and heterogeneous cutaneous disorder that typically develops in middle-aged adults. Despite the significant clinical burden associated with the disorder, little well-conducted molecular research has been undertaken, possibly because of heterogeneity impeding consistent and confident phenotyping. The multiple variants of lichenoid disease bear overlapping clinical and pathologic features despite manifesting as distinct clinical disorders. The first article in this 2-part continuing medical education series provides a comprehensive overview of the clinical and pathologic characteristics of cutaneous lichenoid dermatoses and links these manifestations to recent advances in our understanding of the underlying pathobiology of such diseases.