Thyroid Autoimmunity and Lichen

Abstract

Lichen planus (LP) and lichen sclerosus (LS) are cutaneous-mucous diseases with uncertain epidemiology. Current data, which are likely to be underestimated, suggest a prevalence in the general population of 0.1–4% for cutaneous LP, 1.27–2.0% for oral LP, and 0.1–3.3% for LS. While etiology of lichen is still unknown, clinical and histological evidence show an (auto)immune pathogenesis. Association of lichen with autoimmune thyroid disease (AITD) has been investigated in few studies. This association appears better defined in the case of LS, while is more controversial for LP. In both situations, the frequency of the association is higher in females. We review the available literature on the correlation between the different types of lichen and AITD, and the literature on the genetic risk factors which are shared by both conditions. Such data suggest that a common pathogenic mechanism could be the cause for co-occurrence of lichen and AITD, at least in some patients. Additionally, analyzing literature data and in continuity with our previous work on other autoimmune diseases, we suggest that molecular mimicry could trigger both diseases, and thus explain their co-occurrence.

The Association of Thyroid Disease and Oral Lichen Planus: A Literature Review and Meta-analysis

“…From this study, this association between OLP and HT-related hypothyroidism suggests that thyroid disease may be involved in the pathogenesis of OLP. A molecular mimicry hypothesis was proposed for both lichen planus and HT, in which structural similarities between microbial antigens and human autoimmune reactions can turn a defensive immune reaction into an autoimmune reaction ( 33 ). However, the thyroid diseases in the articles analyzed in this study were not confined to hypothyroidism and HT.…”

Oxidative Stress and Oral Mucosal Diseases: An Overview

“…A common chronic inflammatory disease of the oral mucosa whose etiologic basis is not yet fully understood, OLP is manifested as an exaggerated response to the body's immune system (30). The epidemiological data are also somewhat uncertain, attesting a rate of incidence ranging from 1.27-2.0% in the general population (31). OLP is considered a potential malignant oral condition, although the rate of malignant transformation is low (32,33).…”

Possible Mechanisms Involved in the Cooccurrence of Oral Lichen Planus and Hashimoto’s Thyroiditis

“…HLA-encoded molecules are expressed on the surface of different cells and participate in antigen presentation, restrict cell recognition, and induce immune responses; consequently, nearly all autoimmune diseases are related to HLA. Studies examining the association between HLA alleles in HT and OLP have demonstrated a common genetic susceptibility for these two diseases [96]. The HLA-DRw9 allele is closely related to autoimmune diseases, including HT [97]; this allele is highly prevalent in Chinese OLP patients [98].…”