What is Lichen sclerosus?
Lichen sclerosus (LS) is a chronic, inflammatory skin disease of probable autoimmune aetiology, which most frequently manifests in the anogenital region although it can be found elsewhere on the body [1, 2]. It can have variable age at onset, but most typically affect postmenopausal women and prepubertal girls [2]. The lesions of LS begin as polygonal papules that coalesce (come together) into porcelain white plaques that often have associated oedema, telangiectasia, and comedo-like plug formation [1].
LS can be severely itchy, and painful and may be associated with dysuria and dyspareunia. Less commonly, LS can present as a bullous or haemorrhagic lesion [1].
What are the causes of Lichen sclerosus?
Although the exact cause of LS is still unknown, genetic susceptibility, autoimmune mechanisms, hormonal factors, state of immunity, and possibly infectious agents, have been implicated in the development of LS [3, 2, 4].
Associations with certain human leukocyte antigens (HLA) further indicate its genetic nature [3]. Intriguingly, LS displays affinities with autoimmune disease as well, with up to 80% of patients presenting with autoantibodies against the extracellular matrix protein-1 [5].
Hormonal factors might be at play as well, considering that LS is more common among postmenopausal women and pre-pubertal girls [1]. Occlusion of the genital skin, a possible environmental factor, may also play a role in the pathogenesis of LS [4].
Why is Lichen sclerosus commonly misdiagnosed?
Lichen sclerosus (LS) is a chronic inflammatory skin disease that primarily affects the anogenital area. However, its diagnosis can be challenging due to a variety of factors.
Perhaps the main reason for this misdiagnosis is the lack of characteristic clinical presentation(s) of LS. Instead, the classical features of LS (namely burning pruritus, thinning, hyperkeratosis and parchment skin look) are absent or simply atypical. Furthermore, the pruritus that is usually present as a classic sign, can be absent in up to a third of the patients, occasionally resulting in misdiagnosis [6].
Moreover, it has been underdiagnosed in large part because lesions can appear at different locations in the body, although the most common site of an LS plaque is in the anogenital area. The disorder can be localised (if it affects a specific region of the anogenital area) or generalised (if distinct skin lesions appear in many parts of the body) [7]. Up to 20% of patients have extragenital involvement [7] and this could easily lead to confusion about the true nature of the clinical presentation. For instance, the LS of the oral mucosa has been reported to be extremely rare [8].
Furthermore, LS is often undiagnosed and undertreated, particularly in younger women, possibly due to inadequate knowledge about the disease among healthcare providers [9].
Finally, the diagnosis of LS is established by a skin biopsy. However, diagnosis of LS based on biopsies, a common clinical practice, is not recommended as biopsies can sometimes reveal non-specific but historical literature-confirmed suggestive findings [10].
Conclusion
In conclusion, the atypical presentations, potential for extragenital involvement, underdiagnoses, and limitations of biopsy contribute to the common misdiagnosis of Lichen sclerosus.