Lichen Sclerosus

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Lichen Sclerosus


Introduction


Lichen sclerosus (LS) is one of the commonest skin conditions to affect the vulva. It is a chronic inflammatory condition, the cause of which is unknown. It can affect males but is much more common (possibly up to tenfold) in females. Henri Hallopeau described it as a variant of lichen planus in 1889 and, while it is a distinct condition in its classic form, there are sometimes overlap features between the two disorders.


It is important to recognize and treat this condition appropriately as a scarring process can occur leading to an alteration in the normal architecture of the vulva. This, in turn, can cause problems with function, particularly with sexual intercourse and micturition. Once adequate treatment starts and the inflammation is controlled, this process should not progress; hence, it is important to diagnose and treat early.


There is a small but definite risk of malignancy occurring on LS, estimated at about 3–4%. This tends to occur on the hypertrophic or acanthotic types of the disease.


The vulva and perianal area are the most commonly involved and although LS can be found at other cutaneous sites, particularly on the trunk and limbs, this only occurs in about 10% of women with genital disease. Occasionally patients can present with extragenital lesions and it is vital to examine the genitalia as it is extremely rare for the ano‐genital skin not be involved in these cases.


Incidence


Lichen sclerosus is estimated to affect 3% of the adult female population and 0.1% of children. However, it is likely to be more common than this as it is often poorly recognized and a proportion of patients are asymptomatic and will therefore not seek medical advice.


The condition has a bimodal peak of incidence. It starts in young girls, usually between 3 and 5 years of age, and then in women after the menopause between 55 and 60. It can start in the reproductive years but this is relatively unusual.


Pathophysiology


The cause of LS remains unknown but several factors have been postulated.


Genetic


A positive family history is reported in up to 12% of female patients. There are genetic associations with the DQ7 and DRB1*12 antigens of the HLA system.


Epigenetics


This phenomenon relates to a change in the genome that results in a functional alteration in the expression of a disease. There is no change in DNA sequence. Altered expression of isocitrate dehydrogenase and aberrant global methylation and hydroxymethylation patterns have been shown in vulval LS.


Autoimmunity


IgG autoantibodies targeting extracellular matrix protein 1 have been demonstrated (74% versus 7% controls) and antibodies to the basement membrane zone components BP180 and BP230 are seen in a third of patients.


Hormonal factors


Reduced dihydrotestosterone is seen in patients with untreated LS and loss of androgen receptors has been demonstrated in genital and extragenital LS. The use of oral contraceptives, especially those with antiandrogen properties, has been shown to be higher in those with LS.


Infection


The role of Borrelia burgdorferi has been postulated but there is no consistent evidence that this is significant.


Trauma


Lichen sclerosus exhibits the Koebner phenomenon whereby skin disease occurs at sites of trauma. The extragenital lesions are often seen at sites of friction, for example around the waistline or under breasts or shoulder straps. Lichen sclerosus has also been reported to occur in scars and skin grafts, after sunburn and in radiotherapy fields. It can be seen in episiotomy scars on the perineum.


Role of the Skin Immune System


The inflammatory infiltrate in LS is composed mainly of T cells and there are increased levels of TH1‐specific cytokines, all in keeping with an autoimmune phenotype.


Histological features


The classic histological appearances of LS are a thinned atrophic epidermis and a band of homogenous, hyalinized collagen in the upper dermis overlying a lymphocytic cell infiltrate (Figure 12.1). In early disease, lichenoid changes similar to those seen in LP can occur and may make diagnosis difficult.

Image described by caption and surrounding text.

Figure 12.1 Histology of LS.


It is important to note the thickness of the epidermis as cases where it is thickened and acanthotic may be at greater risk of developing a squamous cell carcinoma and should be followed very carefully.


Symptoms


The main symptom is pruritus and most patients describe this as intense, sometimes waking them at night. Minor bleeding may occur secondary to excoriation and fissuring. Some patients may scratch so much that they can induce small areas of ulceration.


If fissuring occurs, discomfort with micturition is a problem. Pain on defaecation and secondary constipation are reported by patients and this is a particular issue in children where constipation can be a predominant and presenting feature.


The introitus can be narrowed due to scarring and this can lead to dyspareunia. If left untreated, scarring can progress, eventually leading to apareunia and problems with the urinary stream which may be diverted and spray on to the thighs.


A small proportion of patients are symptomatic and the disease is discovered as an incidental finding.


Clinical features


The classic lesion in LS is a white plaque, which can be atrophic (Figure 12.2) or sclerotic (Figure 12.3). At extragenital sites, follicular delling is a feature and if the areas are atrophic, the surface of the skin is said to look like wrinkled cigarette paper. Ecchymosis or purpura is a pathognomonic feature and can be seen at genital and extragenital sites (Figure 12.4).

Photo displaying atrophic extragenital LS on skin.

Figure 12.2 Atrophic extragenital LS.

Photo displaying sclerotic extragenital LS on skin.

Figure 12.3 Sclerotic extragenital LS.

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Mar 15, 2018 | Posted by in OBSTETRICS | Comments Off on Lichen Sclerosus
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