Proteolytic enzyme activity measured on extracellular matrix in vulval dystrophies

Alterations in fibrillin as well as collagens I and III and elastin occur in vulval lichen sclerosus

BACKGROUND

The clinical features of lichen sclerosus, which include atrophy, scarring, fragility and tendency to form ecchymoses with only slight trauma, suggest that there is an alteration in the extracellular matrix fibres that are responsible for the tensile strength of the dermis. However, the precise nature of these changes is poorly understood.

METHODS

Biopsies from 16 patients with untreated, histologically confirmed, vulval lichen sclerosus were examined immunohistochemically using polyclonal antibodies to collagens I and III and a monoclonal antibody to elastin. Twelve of the lichen sclerosus specimens were also stained with a monoclonal antibody to fibrillin. Normal vulva tissue and patients' uninvolved thigh were used as controls.

RESULTS

In the lichen sclerosus specimens, collagens I and III stained with a more homogeneous pattern than in the control tissues. Reduced numbers of elastin fibres were seen in the zone of sclerosus in 15 of the 16 lichen sclerosus specimens. In the control tissue fibrillin fibres were seen as a fine network of fibres in the upper dermis arranged at right angles to and inserting into the basement membrane and forming a fine network throughout the dermis. In the lichen sclerosus specimens, although fibrillin microfibrils were still seen inserting at right angles into the basement membrane, below this the fibrillin staining was reduced in the upper dermis in 11 of the 12 lichen sclerosus specimens. The zone of reduced fibrillin staining was greatest in those specimens where the band of inflammation was deep in the dermis.

CONCLUSIONS

The distribution of collagens I and III, elastin and fibrillin are altered in lichen sclerosus and this is likely to contribute to the fragility, scarring and atrophy seen clinically in lichen sclerosus.

Do plasminogen activators play a role in lichen sclerosus?

The histological changes of lichen sclerosus suggest that significant remodelling of the extracellular matrix is occurring. As the proteases of the plasminogen activator system have been implicated in tissue remodelling, cell migration and tumour invasion, we performed an immunohistochemical study to look for evidence of alteration in the expression of plasminogen/plasmin, urokinase-type plasminogen activator, tissue-type plasminogen activator and alpha2-antiplasmin in biopsies of clinically typical vulval lichen sclerosus obtained from 11 untreated adult women. Normal vulva obtained from gynaecological procedures and samples of the patients' uninvolved thigh tissue were used as controls. No significant difference was seen in the staining pattern between the lichen sclerosus tissue and control tissue. However, although we found no immunohistochemical evidence that the plasminogen activator system is involved in the pathogenesis of vulval lichen sclerosus, it may be that other proteases are involved.

Does lichen sclerosus play a central role in the pathogenesis of human papillomavirus negative vulvar squamous cell carcinoma? The itch-scratch-lichen sclerosus hypothesis

In the past decade, two types of vulvar squamous cell carcinoma (SCC) have been delineated, Human papillomavirus (HPV) positive and negative. Clinicopathologic, virologic, cytomorphometric, and genetic differences support the view that these two types of carcinoma are fundamentally different and that HPV-negative carcinoma is not simply carcinoma where viral DNA has not been able to be identified. The traditional view of HPV-negative carcinoma is that it is caused by chronic tissue damage from itching and scratching. However, itching and scratching alone do not explain the close association of carcinoma with lichen sclerosus, nor the absence of such an association with other itchy conditions such as eczema or psoriasis. These observations point to a role for lichen sclerosus in the pathogenesis of vulvar carcinoma. Most observations about the etiology of lichen sclerosus can be grouped into its immunogenetic or genital predisposition, or the Köbner phenomenon. In the itch-scratch-lichen sclerosus hypothesis, lichen sclerosus is postulated to occur as a Köbner phenomenon in women with the susceptible immunophenotype who scratch because of genital irritants such as urine, vaginal secretions and smegma, and psychological factors. Lichen sclerosus, itself a very itchy condition, contributes to a vicious cycle of itching and scratching which leads to superimposed lichen simplex chronicus, squamous cell hyperplasia, and ultimately carcinoma. The itch-scratch-lichen sclerosus hypothesis reconciles the traditional itch-scratch hypothesis with the strong clinicopathologic association of lichen sclerosus with carcinoma.

Treatment of vulvar lichen sclerosus in the elderly: an update

Lichen sclerosus et atrophicus is a disorder of the skin that can occur anywhere on the body and in all age groups but mainly affects middle-aged and elderly women in the vulvoperineal area. It consists of ivory or pink papules or macules that eventually coalesce into thin, gray, parchment-like areas. Clinically, the main symptoms are severe and intractable itching and vaginal soreness with dyspareunia. Although it has been described to be associated with an increased risk for epithelial malignancy this, in fact, very rarely occurs. The exact nature of LSA is still unknown. The accumulation of evidence does little to clarify its pathogenesis and etiology. The different reports indicate at least three general possibilities; autoimmune, metabolic, and more recently infectious etiology. The coexistence of such diverse findings in one disease entity may indicate one of the two; either we are facing a group of very similar conditions, which will be separated in the future into several closely related clinical entities, each with its own etiology, or that all findings represent a complex multi-step single pathogenetic mechanism. The latter possibility seems more probable because it has previously been suggested that B. burgdorferi, a recent prime suspect in the pathogenesis of LSA, may induce both metabolic and autoimmune abnormalities in the course of infection. New therapeutic options and attitudes emerge that dramatically improved the conservative treatment of this disease (Table 5).(ABSTRACT TRUNCATED AT 250 WORDS)