What is oral lichen planus?

Lichen planus is a common dermatologic disease that affects the oral mucosa caused by an overreaction of T lymphocytes in the immune system. Most patients that present with lichen planus are middle aged, and are more commonly female. The underlying main factor that causes lichen planus remains unknown.

The lesions of lichen planus are multifocal, meaning they show up in multiple areas of the oral mucosa. Typically, they present bilaterally on each side of the cheek (buccal mucosa).

There are two presentations that are characteristic of lichen planus – reticular and erosive.

Reticular lichen planus has a white, lacey look with underlying erythema that is described as Wickham’s stria. It is the most common form of lichen planus.

Erosive lichen planus has a central area of ulceration that is painful, but can still present Wickham’s stria like that seen in reticular lichen planus. Pain is a defining characteristic of erosive lichen planus.

(n.d.) A. Pourian. White Lesions. A.T. Still Missouri School of Dentistry and Oral Health.

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What is the connection between oral lichen planus and hypothyroidism?

The thyroid organ is responsible for secreting hormones that monitor growth and development. There are various diseases of the thyroid, including Hashimoto’s thyroiditis which is the most common cause of hypothyroidism.

A meta-analysis was conducted of the associated between lichen planus and hypothyroidism and found a significantly high prevalence of thyroid disease among oral lichen planus patients compared with controls. The meta-analysis included eight studies in the review, but only four were used in the final review.

The mechanism between oral lichen planus and thyroid disease is not entirely clear. However, it can be assumed that thyroid disease may be involved in the pathogenesis of oral lichen planus, or that oral lichen planus is a clinical manifestation of thyroid disease.

Li, D., Li, J., Li, C., Chen, Q., & Hua, H. (2017). The Association of Thyroid Disease and Oral Lichen Planus: A Literature Review and Meta-analysis. Frontiers in Endocrinology, 8. doi: 10.3389/fendo.2017.00310