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Introduction
Lichen planus (LP) is a chronic, autoimmune, and inflammatory condition that affects the skin and is mediated by T cells. Notably, it is more prevalent in middle-aged women1,2. The etiology of the disease remains unknown, but possible trigger factors have been identified, including anxiety, diabetes, autoimmune diseases, drugs, stress and genetic predisposition. LP can affect several parts of the body, such as the skin, nails, and oral, vulvovaginal, esophageal, laryngeal, and conjunctival mucous membranes. LP has different subtypes that can be characterized depending on the site of involvement and morphology of the lesion. Most cases manifest with violaceous papules or plaques, which can be very pruritic and can be covered by white striations (Wickham striae)3,4. The disease affects < 1% of the world’s adult population; however, the oral form, which is the most prevalent, is present in up to 4% of adults5. Currently, epidemiological studies regarding LP are few and do not reflect the situation in Brazil.
Several studies have reported a relationship between hepatitis C virus infection and LP, and they have suggested that hepatitis C could be an etiological agent of LP6. However, the causal relationship between the two diseases has not been established; if they are related, it is unknown whether LP lesions are triggered directly by the virus or through an immunological reaction. Meanwhile, a higher prevalence of the oral LP subtype has been described in patients with positive hepatitis C serology. Nevertheless, data regarding the relationship between hepatitis C and LP remain controversial and vary depending on the country and prevalence of hepatitis C7,8.
Objectives
This study assessed the epidemiological profile of patients with LP treated in a tertiary hospital and compared the findings with those in the literature.
Materials and methods
We conducted a retrospective cross-sectional observational study that evaluated the electronic medical records of patients with histopathologically confirmed LP who presented to the dermatology service from January 2020 to January 2021. Histopathological findings of LP included orthokeratic hyperkeratosis, wedge hypergranulosis, irregular acanthosis in sawtooth arrangement, dermoepidermal band-like inflammatory infiltrate, and liquefaction degeneration of the basal layer9. Additionally, patient data, including comorbidities, smoking, and hepatitis C serology, were obtained from the medical records, if available. Patients without histopathological confirmation of LP were excluded from the study.
Results
A total of 24 patients were included in the study. The mean age of the participants was 53.6 years, 16 (66.6%) patients were Fitzpatrick phototype IV/V, and 19 (79%) were women. Of the 24 patients, 13 (55%) had comorbidities. Among the most prevalent comorbidities were hypertension (10 patients, 42%), diabetes mellitus (six patients, 25%), hyperthyroidism (one patient, 4%), dyslipidemia (two patients, 8%), and depressive disorder (three patients, 13%), and seven patients reported smoking habits (29%), Overall, 22 (92%) patients had cutaneous lesions, six (25%) had nail lesions, and three (12%) had oral mucosal lesions. Meanwhile, 15 (63%) had cutaneous LP, nine (60%) had classical LP, two (13%) had pigmented LP, one (7%) had hypertrophic LP, and one (7%) had inverted LP. Notably, there were two (8%) cases of lupus erythematosus/LP overlap. Moreover, six (25%) patients presented with nail alterations and chromonychia due to LP. Regarding hepatitis C serology, 20 patients (83%) had documented serology for hepatitis C, but only one patient (4%) had a positive serology, underwent treatment 5 years before the appearance of lesions and currently has a negative serology (Table 1).
Table 1 Epidemiological profile of the 24 patients with lichen planus
| Variables | Number (n = 24) | % |
|---|---|---|
| Age | ||
| < 20 | 1 | 4% |
| 20-40 | 2 | 8% |
| 40-60 | 11 | 46% |
| > 60 | 10 | 42% |
| Phototype | ||
| I or II | 8 | 33.33% |
| III or IV | 8 | 33.33% |
| V or VI | 8 | 33.33% |
| Gender | ||
| Men | 5 | 21% |
| Women | 19 | 79% |
| Comorbidities | ||
| Yes | 13 | 55% |
| No | 11 | 45% |
| Related comorbidities | ||
| Hyperthyroidism | 1 | 4% |
| Diabetes mellitus type 2 | 4 | 17% |
| Diabetes insulin-dependent | 2 | 8% |
| Prediabetes | 2 | 8% |
| Dyslipidemia | 2 | 8% |
| Depression | 3 | 13% |
| Hypertension | 10 | 42% |
| Patients with more than one comorbidity | 8 | 62% |
| Smoking | ||
| Yes | 7 | 29% |
| No | 17 | 71% |
| Sub-type of LP | ||
| Cutaneous | 15 | 63% |
| Cutaneous + nail | 4 | 17% |
| Cutaneous + oral | 3 | 12% |
| Nail | 2 | 8% |
| Types of cutaneous LP (n = 15) | ||
| Classical LP | 9 | 60% |
| Pigmented LP | 2 | 13% |
| Hypertrophic LP | 1 | 7% |
| Inverted LP | 1 | 7% |
| Overlap between lupus erythematosus and LP | 2 | 13% |
| HCV serology (n = 20) | ||
| HCV positive | 0 | 0% |
| HCV negative | 20 | 100% |
Discussion
Our findings show that patients with higher phototypes have a higher prevalence of LP, which is consistent with data in the literature10,11. Notably, hypertension and diabetes were highly prevalent among our patients with LP. In several studies, dyslipidemia is associated with LP, but diabetes and hypertension are not; this may be attributed to metabolic syndrome alterations, which is a known risk factor for LP and other inflammatory dermatoses such as psoriasis12,13.
From 2000 to 2021, 279,872 confirmed cases of hepatitis C were reported in Brazil; however, there is a decreasing trend in the number of cases. In 2016, there were 25,324 reported cases of hepatitis C, with a prevalence of 1.22%/100,000 inhabitants. In 2019 before the COVID-19 pandemic, there were 23,111 reported cases of hepatitis C, with a prevalence of 1.09%/100,000 inhabitants14. The decrease in the number of cases may be attributed to the introduction of antiretroviral drugs capable of curing the disease, which are distributed free of charge by the unified health system.
Although an association between LP and hepatitis C were reported by several studies, variables, such as the location where the studies were conducted, should be considered. In countries with a higher prevalence of hepatitis C, a greater association between the two diseases was reported. Meanwhile, there are authors who argue that the association between hepatitis C and LP may be the result of variants of the virus found only in certain geographic regions7,15. Despite the know association between LP and hepatitis C, we did not find an association between the two diseases.
In our study, most of the patients were women over 50 years old. Additionally, there was a high prevalence of comorbidities, including hypertension and diabetes, and smokers among the study population. Smoking is considered to be associated with oral LP10; in our study, smoking was associated with a greater predisposition for the cutaneous form of LP. The most evident LP subtype in our study was the classical cutaneous subtype, followed by the nail and oral subtypes.
The limitations of our study were the limited sample size and short analysis time. Oral biopsies were rarely performed and could justify the reduced number of oral variants.
Conclusion
Hepatitis C virus is reported to be an etiological agent of LP, suggesting that cutaneous and mucosal lesions may be caused by either the direct action of the virus or by an induced immune response7. However, in our sample, there was only one case of LP with a previous hepatitis C, and this patient developed LP 5 years after completing antiviral treatment.
Further studies are suggested to elucidate both the association and etiology. The association between the two diseases is controversial and varies according to the literature used as a reference.
