Track: Clinical Studies

Topic: Neoplasia,Carcinogensis,Tumor Biology

Abstract:

Differentiated vulvar intraepithelial neoplasia (dVIN), the precursor lesion of human papillomavirus-independent squamous cell carcinoma, can be challenging to distinguish from inflammatory vulvar dermatoses. Current diagnostic criteria for dVIN are somewhat poorly defined outside of aberrant p53 expression by immunohistochemistry, and low interobserver agreement in diagnosis is documented. Suprabasilar mitotic figures are often used as a major factor in support of a diagnosis of dVIN; however, inflammatory dermatoses can show many mitotic figures, including suprabasilar mitoses. This study evaluates whether the number and location of mitoses in dVIN and inflammatory dermatoses can be used to differentiate these processes. Cases of dVIN (N = 20) and inflammatory dermatoses (N = 24) were evaluated. The total number of mitoses in four contiguous high-power fields, starting in a hotspot area, was quantified. The mean number of mitoses was 6.4 in dVIN and 3.7 in inflammatory lesions (p = 0.1). Ten (41.7%) of the inflammatory cases were diagnostic of lichen sclerosus; these demonstrated lower mitotic activity (mean = 2.3) compared with either dVIN or other inflammatory lesions (p<0.003 and p<0.04, respectively). Twelve (60%) of the dVIN cases demonstrated suprabasilar mitoses, compared to thirteen (54%) of the inflammatory lesions. Our findings suggest that mitotic activity, including suprabasilar mitoses, may not be a helpful marker in differentiating dVIN from inflammatory lesions, as the latter can demonstrate significant mitotic activity. However, there may be some utility in evaluation of mitoses when the differential diagnosis is limited to lichen sclerosus and dVIN, as dVIN shows significantly higher mitotic activity.

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Michael Crawford, MD