Vulvar intraepithelial neoplasia (VIN) is a distressing condition that may require painful and disfiguring treatments. It is particularly problematic because more than a quarter of patients will experience recurrence of their disease after primary therapy. In this column we will explore the risk factors for recurrence, recommendations for early detection, and options to minimize its incidence.
Dr. Emma C. Rossi
VIN was traditionally characterized in three stages (I, II, III). However, as it became better understood that the previously named VIN I was not, in fact, a precursor for malignancy, but rather a benign manifestation of low-risk human papillomavirus (HPV) infection, it was removed from consideration as VIN. Furthermore, our understanding of VIN grew to recognize that there were two developmental pathways to vulvar neoplasia and malignancy. The first was via high-risk HPV infection, often with tobacco exposure as an accelerating factor, and typically among younger women. This has been named “usual type VIN” (uVIN). The second arises in the background of lichen sclerosus in older women and is named “differentiated type VIN” (dVIN). This type carries with it a higher risk for progression to cancer, coexisting in approximately 80% of cases of invasive squamous cell carcinoma. In addition, the progression to cancer appears to occur more quickly for dVIN lesions (22 months compared with 41 months in uVIN).1
While observation of VIN can be considered for young, asymptomatic women, it is not universally recommended because the risk of progression to cancer is approximately 8% (5% for uVIN and 33% for dVIN).1,2 Both subtypes of VIN can be treated with similar interventions including surgical excision (typically a wide local excision), ablative therapies (such as CO2 laser) or topical medical therapy such as imiquimod or 5-fluorouracil. (false-negative biopsies), and adequacy of margin status. However, given the proximity of this disease to vital structures such as the clitoris, urethral meatus, and anal verge, as well as issues with wound healing, and difficulty with reapproximation of vulvar tissues – particularly when large or multifocal disease is present – sometimes multimodal treatments or medical therapies are preferred to spare disfigurement or sexual, bladder, or bowel dysfunction.
Excision of VIN need not be deeper than the epidermis, although including a limited degree of dermis protects against incomplete resection of occult, coexisting early invasive disease. However, wide margins should ideally be at least 10 mm. This can prove to be a challenging goal for multiple reasons. First, while there are visual stigmata of VIN, its true extent can be determined only microscopically. In addition, the disease may be multifocal. Furthermore, particularly where it encroaches upon the anus, clitoris, or urethral meatus, resection margins may be limited because of the desire to preserve function of adjacent structures. The application of 2%-5% acetic acid in the operating room prior to marking the planned borders of excision can optimize the likelihood that the incisions will encompass the microscopic extent of VIN. As it does with cervical dysplasia, acetic acid is thought to cause reversible coagulation of nuclear proteins and cytokeratins, which are more abundant in dysplastic lesions, thus appearing white to the surgeon’s eye.
However, even with the surgeon’s best attempts to excise all disease, approximately half of VIN excisions will have positive margins. Fortunately, not all of these patients will go on to develop recurrent dysplasia. In fact, less than half of women with positive margins on excision will develop recurrent VIN disease.2 This incomplete incidence of recurrence may be in part due to an ablative effect of inflammation at the cut skin edges. Therefore, provided that there is no macroscopic disease remaining, close observation, rather than immediate reexcision, is recommended.
Positive excisional margins are a major risk factor for recurrence, carrying an eightfold increased risk, and also are associated with a more rapid onset of recurrence than for those with negative margins. Other predisposing risk factors for recurrence include advancing age, coexistence of dysplasia at other lower genital sites (including vaginal and cervical), immunosuppressive conditions or therapies (especially steroid use), HPV exposure, and the presence of lichen sclerosus.2 Continued tobacco use is a modifiable risk factor that has been shown to be associated with an increased recurrence risk of VIN. We should take the opportunity in the postoperative and surveillance period to educate our patients regarding the importance of smoking cessation in modifying their risk for recurrent or new disease.
HPV infection may not be a modifiable risk factor, but certainly can be prevented by encouraging the adoption of HPV vaccination.
Topical steroids used to treat lichen sclerosus can improve symptoms of this vulvar dystrophy as well as decrease the incidence of recurrent dVIN and invasive vulvar cancer. Treatment should continue until the skin has normalized its appearance and texture. This may involve chronic long-term therapy.3
Recognizing that more than a quarter of patients will recur, the recommended posttreatment follow-up for VIN is at 6 months, 12 months, and then annually. It should include close inspection of the vulva with consideration of application of topical 2%-5% acetic acid (I typically apply this with a soaked gauze sponge) and vulvar colposcopy (a hand-held magnification glass works well for this purpose). Patients should be counseled regarding their high risk for recurrence, informed of typical symptoms, and encouraged to perform regular vulva self-inspection (with use of a hand mirror).
For patients at the highest risk for recurrence (older patients, patients with positive excisional margins, HPV coinfection, lichen sclerosus, tobacco use, and immunosuppression), I recommend 6 monthly follow-up surveillance for 5 years. Most (75%) of recurrences will occur with the first 43 months after diagnosis with half occurring in the first 18 months.2 Patients who have had positive margins on their excisional specimen are at the highest risk for an earlier recurrence.
VIN is an insidious disease with a high recurrence rate. It is challenging to completely resect with negative margins. Patients with a history of VIN should receive close observation in the years following their excision, particularly if resection margins were positive, and clinicians should attempt to modify risk factors wherever possible, paying particularly close attention to older postmenopausal women with a history of lichen sclerosus as progression to malignancy is highest for these women.
Dr. Rossi is assistant professor in the division of gynecologic oncology at the University of North Carolina at Chapel Hill. She said she had no relevant financial disclosures. Email Dr. Rossi at obnews@mdedge.com.
References
1. Pathology. 2016 Jun 1;48(4)291-302.