Keratinization interferes to a greater or lesser degree with the filter effect upon which grading of colposocpic images on the cervix and vagina depends. Keratin is opaque, making evaluation of thickness of the affected vulvar epithelium difficult. Therefore, the prediction of histological diagnosis, often possible on the cervix and vagina is much more difficult for vulvar lesions.
Until recently there has been no attempt to systematize colposcopic findings on the vulva. Trying to classify vulvar findings it is possible to use the same descriptive process for the vulva as for the cervix. For years the classification of colposcopical findings on the vulva was based on a few important characteristics of the lesions.
Combining particular features of vulvar lesion can help colposocpical prediction of its histological nature, but this is much less reliable than colposcopical grading of cervical lesions.
1. Color
The principal feature of vulvar lesion, from colposcopic point of view, is the color. This is probably most informative distinction of the lesion. Color changes are common in the vulvar epithelium. They are easily visible to naked eye. Color of vulvar lesions varies from white to black. It will depend upon pigmentation, vascularity of the dermis and the thickness of the overlying epithelium. Including all the varieties in between, vulvar lesions can basically be:
White lesions are not always neoplastic. To the development of white color contribute:
Superficial keratin layer
Any degree of depigmentation
Relative avascularity of tissue
Reaction to acetic acid.
When superficial keratin undergoes maceration due to the increased moisture of vulvar area, it turns opaque and its color becomes white or gray. The thicker the keratin layer is, the effect is more expressed.
Depigmentation is loss or absence of melanin pigmentation. It develops if melanocytes in basal layer are lost or destroyed or when these cells lost their ability to produce melanin (vitiligo). Localized white lesions may result from transient loss of pigment in a residual scar after healing of an ulcer (leukoderma).
Relative decrease in vascularity appears when superficial blood vessels become narrow and the distance between them increase, which happens in Lichen sclerosus.
Histologically white lesions may present
Non-neoplastic epithelial disorders
HPV infection
VIN
To differentiate VIN from other white lesions which appear on vulva, the biopsy should be taken.
Normal coloring of the skin is the result of light reflection from the superficial blood vessels situated in dermis. As light traverse through the epidermis which lies above the dermis decrease in the thickness of epithelium or any increase in vascularity gives the red appearance of skin. Red lesion results from thinning or ulceration of epidermis, the vasodilatation of inflammation or an immune response or the neovascularisation of neoplasia.
Many of these red lesions are simptomatic and accompanied with pruritus, pain and occasional bleeding due to fragility of superficial capillaries. Diffuse redness is usually associated with benign processes (infections and different dermatoses), while each localized red lesion may be suspicious to neoplasia.
Red lesions may present local immune response or inflammatory reaction in conditions such as
Dark lesions are due to an increased amount or concentration of melanin or blood pigment. Vulvar lesions appear dark if melanin is present intraepithelially and/or intradermally. In these lesions synthesis of melanin is amplified in epidermal melanocytes. The excess of melanin is afterwards ejected in papillary dermis wherefrom is taken by melanofages by process of fagocytosis. This mechanism is known as "melanin incontinence" and produces pigmented appearance of many VIN lesions.
Pigmentation of vulvar skin may occur after trauma. Vulvar skin may darken following the use of estrogen cream applied to the vulva and vagina for the treatment of vaginitis or after oral contraceptive use.
Vulvar lesions may show any other variety of color. Particularly recognizable are lesions which originate from vascular tissue such as angiomas or choriocarcinomas, which are typically violet. Necrotic tissue usually has yellow coloring.
2. Vascular pattern
It has been pointed out that vascular pattern can not be easily seen on surfaces covered by keratinized skin, particularly on hair-bearing areas. If punctations and mosaic are present, intravascular distance (the size of mosaic fields or distance between punctations) is evaluated on the same manner as when colposcopical grading of cervical lesions is concerned. Clearly visible atypical vessels are usually suggestive to invasive cancer.
3. Surface configuration
Whatever surface of the lesion is, all vulvar lesions can be regarded in relation to the level of surrounding skin. They can be situated:
Below the level of surrounding skin (erosions and ulcerations)
In the skin (macula, aceto-white lesions, pigmentation disorders)
Erosions and ulcerations are below the level of the surrounding epithelium. They are typical findings for some infections and dermatoses such as Herpes infection, Syphilis, Behçet's or Crohn's disease and other ulcerative and bullous skin disorders. Ulcerative lesions may suggest a granulomatous sexually transmitted disease or cancer.
Lesions in the level of skin are usually part of dermatological conditions such as allergic reactions or pigmentation disorders. Subclinical HPV infection and VIN can also be localized in the thickness of epithelium only, particularly if present on the skin of labia minora or vestibular epithelium. In these cases they are recognized as the change in color.
Majority of lesions are raised above the surrounding skin. HPV infections, VIN and invasive cancer usually present as raised lesions. Other conditions like benign tumors, tumor-like conditions and dermatologic diseases and leukoplakia of any cause, should be excluded by biopsy.
Superficial aspect of all these lesions wherever they are situated can be smooth (hemispheric or flat) or irregular (micropapillary, microcondilomatous, villiform).
4. Topography
Vulvar lesions can be sited on
Skin
- Hair-bearing
- Non hair-bearing
Mucosa
Many vulvar lesions are multisited. Examine all sites of vulva!
Vulvar lesions may be
Unifocal
Multifocal
Majority of the VIN changes are multifocal. Look for multifocal changes!
Some colposcopical classifications of vulvar findings, define variety of vulvar lesions very precisely. Although they are very useful, for practical purposes, abnormal colposcopic appearances in the vulva may be summarized as follows:
Single of multifocal white, red or pigmented lesions apparent before the application of acetic acid
Aceto-white change appearing after prolonged soaking of the skin using acetic acid-soaked swabs.
Abnormal vessel patterns which may be seen but are less common, probably due to the masking effect of keratinization.
On the basis of macroscopical aspect and the distribution of vulvar changes it is not possible to distinguish between various types of vulvar lesions. Distinction based on the characteristics of vulvar lesions is not indicative of histology. Therefore the rule is: for definite diagnosis of vulvar lesion - perform biopsy. On the other hand vulvoscopy can exactly localize the lesion, and although not having the important role in the presence of clinically evident lesion, it is very useful in directing the biopsy site and mapping the limits of the lesion at the time of excision.
Types of vulvar lesions
Vulvar pathology is a concern of several specialities which reflects the vulvar complex morphology and variety of functions through the life cycle of women.
Vulva is the region where numerous local or systemic diseases can express. Spectrum of abnormalities which can affect vulva is ranging from infections, inflammatory conditions and dermatoses similar to those encountered in extra-genital skin to vulvar intraepithelial neoplasia and invasive cancer. The last decade has witnessed significant advances in the study of vulvar pathology, making the terminology of vulvar disease even more confusing than it has already been over the years.
Pathology of the vulva is very complex, includes many other conditions and generally may be divided into:
These conditions are associated with variety of appearances and in some instances may mimic the appearance of cancer and precancer. Realizing the complexity of vulvar pathology only a selected few will be addressed, because of their importance to the clinician.
