Medically speaking, the term denotes a squamous intraepithelial lesion of the vulva that shows dysplasia with varying degrees of atypia. The epithelial basement membrane is intact and the lesion is thus not invasive but has invasive potential.

The terminology of VIN evolved over several decades. In 1989 the Committee on Terminology, International Society for the Study of Vulvar Disease (ISSVD) replaced older terminology such as vulvar , Bowen's disease, and Kraurosis vulvae by a new classification system for "Epithelial Vulvar Disease":

- Nonneoplastic epithelial disorders of vulva and mucosa:

- Lichen sclerosus

- Squamous hyperplasia

- Other dermatoses

- Mixed neoplastic and nonneoplastic disorders

- Intraepithelial neoplasia

- Squamous vulvar intraepithelial neoplasia (VIN)

- VIN I, mildest form

- VIN II, intermediate

- VIN III, most severe form including carcinoma in situ of the vulva

- Non-squamous intraepithelial neoplasia

- Extramammary Paget's disease

- Tumors of melanocytes, noninvasive

- Invasive disease (vulvar carcinoma)

The ISSVD further revised this classification in 2004, replacing the three-grade system with a single-grade system in which only the high-grade disease is classified as VIN.

VIN is subdivided into: (Robbins Pathological Basis of Disease, 9th Ed)

Classic vulvular intraepithelial neoplasia: associated with developing into the warty and basaloid type carcinoma. This is associated with carcinogenic genotypes of HPV and/or HPV persistence factors such as cigarette smoking or immunocompromised states.

Differentiated vulvar intraepithelial neoplasia also known as VIN Simplex: is associated with vulvar dermatoses such as lichen sclerosus. It is associated with atypia of the squamous epithelium.

The most common location by far is the gingival margin and other areas of the masticatory oral mucosa, these occur more frequently in the fifth decade of life, and have good prognosis, the treatment of choice for oral VXs is surgical excision, and recurrence is rare.

The condition can affect other organs of body, such as the penis, vulva, and can occur in anal region, nose, the ear, lower extremity, scrotum.

The term Vulvar intraepithelial neoplasia (VIN) refers to particular changes that can occur in the skin that covers the vulva. VIN is not cancer, and in some women it disappears without treatment. If the changes become more severe, there is a chance that cancer might develop after many years, and so it is referred to as a precancerous condition.

Many malignancies can develop in vulvar structures. The signs and symptoms can include:

- Itching, burn, or bleeding on the vulva that does not go away.

- Changes in the color of the skin of the vulva, so that it looks redder or whiter than is normal.

- Skin changes in the vulva, including what looks like a rash or warts.

- Sores, lumps, or ulcers on the vulva that do not go away.

- Pain in the pelvis, especially during urination or sex.

Typically, a lesion presents in the form of a lump or ulcer on the labia majora and may be associated with itching, irritation, local bleeding or discharge, in addition to pain with urination or pain during sexual intercourse. The labia minora, clitoris, perineum and mons are less commonly involved. Due to modesty or embarrassment, patients may put off seeing a doctor.

Melanomas tend to display the typical asymmetry, uneven borders and dark discoloration as do melanomas in other parts of the body.

Adenocarcinoma can arise from the Bartholin gland and present with a painful lump.

Vaginal intraepithelial neoplasia (VAIN) is a condition that describes premalignant histological findings in the vagina characterized by dysplastic changes.

The disorder is rare and generally has no symptoms. VAIN can be detected by the presence of abnormal cells in a Papanicolaou test (Pap smear).

Like cervical intraepithelial neoplasia, VAIN comes in three stages, VAIN 1, 2, and 3. In VAIN 1, a third of the thickness of the cells in the vaginal skin are abnormal, while in VAIN 3, the full thickness is affected. VAIN 3 is also known as carcinoma in-situ, or stage 0 vaginal cancer.

Infection with certain types of the human papillomavirus ("high-risk types") may be associated with up to 80% of cases of VAIN. Vaccinating girls with HPV vaccine before initial sexual contact has been shown to reduce incidence of VAIN.

One study found that most cases of VAIN were located in the upper third of the vagina, and were multifocal. In the same study, 65 and 10% patients with VAIN also had cervical intraepithelial neoplasia and vulvar intraepithelial neoplasia, respectively.

In another study, most cases of VAIN went into remission after a single treatment, but about 5% of the cases studied progressed into a more serious condition despite treatment.

Differential diagnosis includes seborrheic keratosis, verruca simplex, condyloma acuminatum, granular cell myoblastoma, vulvar intraepithelial neoplasia, bowenoid papulosis, erythroplasia of Queyrat, and verrucous carcinoma

Symptoms are not specific; most patients report itching, burning, and soreness. A small subset of patients may be asymptomatic. Presence of vulvar pain, bleeding, and tumor formation are reported to be more common in patients affected by invasive disease.Signs and symptoms are skin lesions, often mistaken as eczema, that may be itchy or painful.

Almost all women present with uterine fibroids, approximately 76% with dermal manifestations and 10-16% with renal tumors.

The uterine fibroids tend to occur at younger age and larger and more numerous than in general population. They may be distinguishable from sporadic fibroids by special histological features such as prominent nucleoli with perinucleolar halos.

The skin presentation is of asymmetrical, reddish-brown nodules or papules with a firm consistency, predominantly located on the limbs (multiple cutaneous leiomyoma), although they may occur anywhere, including the face. The lesions, which are typically painful and most often present during the third decade of life, are piloleiomyomata—a benign smooth muscle tumour arising from the arrectores pilorum muscles of the skin. These tumours may also arise in the tunica dartos of the scrotum and the mammillary muscle of the nipple (genital leiomyoma), the smooth muscle of blood vessels (angioleiomyoma) and the lung (pulmonary lymphangioleiomyomatosis). A pseudo-Darier sign may be present.

The renal cell carcinoma tends to be of the papillary (type 2) form and tends to occur more commonly in women than men with this syndrome. These cancers present earlier than is usual for renal cell carcinomas (typically in the twenties and thirties) and to be at relatively advanced stages at presentation. Tumours have rarely been reported in children. These tumours occur in ~20% of those with this mutation suggesting that other factors are involved in the pathogenesis.

Warty dyskeratoma must be differentiated from vulvar dysplasia, Bowenoid papulosis, squamous carcinoma, condyloma, and other viral-induced squamous lesions.

Vulvar Paget disease presents as a variety of clinical lesions that may occur over a protracted course. Initially it is velvety, soft, and red or bright pink with scattered white islands of hyperkeratosis. (a strawberry and cream appearance) The lesions become erythematous, plaque like, and desquamating especially when located in dry areas. Rarely the appearance is ulcerated. The borders appear irregular, slightly elevated, and sharply demarcated. The visible borders of vulvar Paget disease are often misleading as Paget cells may spread along the basal layers of normal appearing skin with multicentric foci. Involvement may be extensive including the perianal region, genitocrural, and inguinal folds. Clinical examination should determine the presence of periurethral and perianal lesions. In these cases an involvement of the skin by a noncutaneous internal neoplasm may occur.

Warty dyskeratoma, also known as an Isolated dyskeratosis follicularis, is a benign epidermal proliferation with distinctive histologic findings that may mimic invasive squamous cell carcinoma and commonly manifests as an umbilicated (Having a central mark or depression resembling a navel) lesion with a keratotic plug, WD have some histopathologic similarities to viral warts but it's not caused by HPV and the majority of these lesions display overall histopathologic features consistent with a follicular adnexal neoplasm. usually limited to the head, neck, scalp or face and vulva. Lesions are generally and sporadic and may be associated with a follicular unit. Oral involvement, particularly the hard palate, and genital involvement have been reported. it can also be thought of as one of the manifestations of focal acantholytic dyskeratosis, an epidermal reaction pattern that can be seen in several disorders, including Darier's disease and Grover's disease. But the main Difference between Darier disease and Warty dyskeratoma, is that Darier disease inherited dermatosis (autosomal dominant) consisting of multiple keratotic papules on the face, trunk, and extremities, while WD occurs as an isolated, noninherited, single keratotic nodule mainly confined to the head and neck as mentioned earlier.

Cervical intraepithelial neoplasia (CIN), also known as cervical dysplasia, is the potentially premalignant transformation and abnormal growth (dysplasia) of squamous cells on the surface of the cervix. Cervical intraepithelial neoplasia most commonly occurs on the cervix at the squamo-columnar junction, but can also occur in vaginal walls and vulvar epthelium. The New Bethesda System reports all gynecologic abnormalities termed "SIL" squamous intraepithelial lesions, arising from all areas of female genital tract, and anal canal of both men and women. Like other intraepithelial neoplasias, CIN or [SIL] is not cancer, and it is usually curable. Most cases of CIN remain stable, or are eliminated by the host's immune system without intervention. However a small percentage of cases progress to become cervical cancer, usually cervical squamous cell carcinoma (SCC), if left untreated. The major cause of CIN is chronic infection of the cervix with the sexually transmitted human papillomavirus (HPV), especially the high-risk HPV types 16 or 18. Over 100 types of HPV have been identified. About a dozen of these types appear to cause cervical dysplasia and may lead to the development of cervical cancer. Other types cause warts.

The earliest microscopic change corresponding to CIN is dysplasia of the epithelial or surface lining of the cervix, which is essentially undetectable by the woman. Cellular changes associated with HPV infection, such as koilocytes, are also commonly seen in CIN. CIN is usually discovered by a screening test, the Papanicolau or "Pap" smear. The purpose of this test is to detect potentially precancerous changes. Pap smear results may be reported using the Bethesda System. An abnormal Pap smear result may lead to a recommendation for colposcopy of the cervix, during which the cervix is examined under magnification. A biopsy is taken of any abnormal appearing areas. Cervical dysplasia can be diagnosed by biopsy. A test for Human Papilloma Virus called the Digene HPV test is highly accurate and serves as both a direct diagnosis and adjuvant to the all important pap test which is a screening device and not the final answer in detecting all types of female genital cancers. Endocervical brush sampling at time of pap smear to detect adenocarcinoma and its precursors is necessary along with doctor/patient vigilance on abdominal symptoms associated with uterine and ovarian carcinoma.

Depending on several factors and the location of the infection, CIN can start in any of the three stage, and can either progress, or regress. The grade of squamous intraepithelial lesion can vary.

CIN is classified in grades:

Bowenoid papulosis is a cutaneous condition characterized by the presence of pigmented verrucous papules on the body of the penis. They are associated with human papillomavirus, the causative agent of genital warts. The lesions have a typical dysplastic histology and are generally considered benign, although a small percentage will develop malignant characteristics.

It is considered as a pre-malignant condition. Other terms used to describe the condition are: Erythroplasia of Queyrat, Squamous cell carcinoma in situ and Bowen’s disease. The term "Bowenoid papulosis" was coined in 1977 by Kopf and Bart and is named after dermatologist John Templeton Bowen.

The term “intraepithelial neoplasia” defines a premalignant intraepithelial change.

On the vulva it is termed VIN (vulvar or vulval intraepithelial neoplasia); on the penis, PIN (penile intraepithelial neoplasia); and on or around the anus, AIN (anal intraepithelial neoplasia). The terminology has been very confusing and it is now recommended that the terms Bowen’s disease, erythroplasia of Queyrat, and bowenoid papulosis should not be used for lesions in the anogenital area. However, dermatologists still recognize a distinct clinical variant, bowenoid papulosis, characterized by discrete papules in a younger age group and a tendency for spontaneous regression. Additionally, some authorities believe that erythroplasia of Queyrat and Bowen’s disease remain useful terms in men.

Basal cell carcinoma makes up about 1–2% of vulvar cancer. These tend to be slow-growing lesions on the labia majora but can occur anywhere on the vulva. Their behavior is similar to basal cell cancers in other locations. They often grow locally and have low risk for deep invasion or metastasis.

Treatment involves excision, but these lesions have a tendency to recur if not completely removed.

Symptoms of anal cancer can include pain or pressure in the anus or rectum, a change in bowel habits, a lump near the anus, rectal bleeding, itching or discharge. Bleeding may be severe.

Reed’s syndrome (or familial leiomyomatosis cutis et uteri) is a rare inherited condition characterised by multiple cutaneous leiomyomas and, in women, uterine leiomyomas. It predisposes for renal cell cancer, an association denominated hereditary leiomyomatosis and renal cell cancer, and it is also associated with increased risk of uterine leiomyosarcoma. The syndrome is caused by a mutation in the fumarate hydratase gene, which leads to an accumulation of fumarate. The inheritance pattern is autosomal dominant.

Though Bartholin gland carcinoma is rare, along with other unusual Bartholin gland growths, it many not be the typical practice for clinicians to consider lesions malignant. Early diagnosis can help to prevent the cancer from the glands to surrounding. Though malignancies of the Bartholin gland are rare clinicians biopsy Bartholin gland lesions in older women or when the growth reoccurs or does not respond to original treatment.

Bartholin gland can be differentiated by histology to determine whether the malignancy is due to squamous cell carcinoma, adenoid cystic carcinoma, or adenocarcinomas.

Vulvar childhood pemphigoid is a cutaneous condition, a childhood form of bullous pemphigoid, peculiar variant with involvement of the genital area and perineum.

Multiple cutaneous leiomyomas, also known as Pilar leiomyomas, arise from the arrectores pilorum muscles, and are made up of a poorly circumscribed proliferation of haphazardly arranged smooth muscle fibers located in the dermis that appear to infiltrate the surrounding tissue and may extend into the subcutis.

Sometimes associated with uterine leiomyomas (a combination known as multiple cutaneous and uterine leiomyomatosis, MCUL), these lesions may also be a manifestation of the hereditary leiomyomatosis and renal cell cancer syndrome.

A urogenital neoplasm is a tumor of the urogenital system.

Types include:

- Cancer of the breast and female genital organs: (Breast cancer, Vulvar cancer, Vaginal cancer, Cervical cancer, Uterine cancer, Endometrial cancer, Ovarian cancer)

- Cancer of the male genital organs (Carcinoma of the penis, Prostate cancer, Testicular cancer)

- Cancer of the urinary organs (Renal cell carcinoma, Bladder cancer)

LS can occur without symptoms. White patches on the LS body area, itching, pain, pain during sex (in genital LS), easier bruising, cracking, tearing and peeling, and hyperkeratosis are common symptoms in both men and women. In women, the condition most commonly occurs on the vulva and around the anus with ivory-white elevations that may be flat and glistening.

In males, the disease may take the form of whitish patches on the foreskin and its narrowing (preputial stenosis), forming an "indurated ring", which can make retraction more difficult or impossible. In addition there can be lesions, white patches or reddening on the glans. In contrast to women, anal involvement is less frequent. Meatal stenosis, making it more difficult or even impossible to urinate, may also occur.

On the non-genital skin, the disease may manifest as porcelain-white spots with small visible plugs inside the orifices of hair follicles or sweat glands on the surface. Thinning of the skin may also occur.

Mucosal lentigines (also known as "labial, penile, and vulvar melanosis", and "melanotic macules") is a cutaneous condition characterized by light brown macules on mucosal surfaces.

Most anal cancers are squamous cell carcinomas (epidermoid carcinomas), that arises near the squamocolumnar junction. It may be keratinizing (basaloid) or non-keratinizing (cloacogenic).

Other types of anal cancer are adenocarcinoma, lymphoma, sarcoma or melanoma.