VIN = Vulvar Intraepithelial Neoplasia: What is it? How is it Classified?

VIN = Vulvar Intraepithelial Neoplasia: What is it? How is it Classified?

Vulva is the general name given to the entire female outer reproductive organ in women including mons pubis (groin and hairy section above), big lips (labium majus), small lips (labium minus), clitoris, urethra the location of urinating, and vulvar vestibulum.

What is VIN? VIN Classification

Vulvar intraepithelial neoplasia (VIN) is the precancerous lesion of the vulva. There is an abnormal development of the squamous cells at the vulva, i.e. dysplasia but it cannot be interpreted as cancer.

There is an association obsessed with the diseases of vulva. This association classifies the vulva diseases that are very important for us and defines new terminology. ISSVD, International Society for the Study of Vulvar Diseases has prepared a VIN terminology in 2004.

There the VINs are divided into two subgroups:

  1. 1. Regular, undifferentiated VIN: It is used for HPV related VIN. In this classification having genital warts is considered as VIN 1 at the beginning. On the other hand in VIN 3 cases as in CINs, the cellular abnormalities involve all the tissue however they do not pass the basal membrane and do not sow stromal invasion. This type of VINs usually occurs in multiple loci at the external genital region. You can see an example below. Acetowhite areas show the VIN 3 regions.
  2. 2. Differentiated VIN: It is the terminology used for non HPV related VINs with a base of lichen sclerosis or lichen simplex.

In 2012, as always Americans tried to demolish this classification of ISSVD and create a new definition under the scope of LAST project but, I shall not go in detail an bore you, they failed big. Thus their classification is not widely used.

Both VIN and Vulva cancer is related with HPV infection. Here it is beneficial to refresh some problems and information related to HPV.

You know the HPVs of genital region are examined under two groups:

  1. 1. Oncogenic: It breaks the DNA sequence of the infected person’s cells and attaches its own DNA into this host DNA. Thus a weird, hybrid cell occurs that is on the way to cancer. For example HPV Type 16 and HPV Type 18 are the most known of these.
  2. 2. Non-oncogenic: They enter to the cell of the infected person but do not meddle with the DNA. Of course they cause problems but developing into a cancer is a very limited chance compared to oncogenic ones. Most known ones of the non-oncogenic HPV types are wart forming HPV Type 6 and 11.

When we come to the vulvar intraepithelial neoplasia case, as mentioned above the genital wart is usually accepted as VIN 1 but 92-97% of the genital warts are formed of HPV type 11-6 and these are non-oncogenic HPV types. However VIN 3 is formed generally of oncogenic HPV types like Type 16, Type 18 or 33. And clinically the actual important thing is the VIN 3 cases. Thus when you ask what is my condition, what will be the treatment, the pathology report is extremely important.

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