Distinguishing Erosive Lichen Planus From Differentiated Vulvar Intraepithelial Neoplasia

Erosive lichen planus (LP) and differentiated vulvar intraepithelial neoplasia (dVIN) may display overlapping histopathologic features.

We searched the local pathology database for vulvar biopsies reported as dVIN or erosive vulvitis during 2011 to 2013 inclusive. After review of patient notes and slides, there were 5 cases with a clinical appearance and course consistent with erosive LP and histopathology showing epithelial regeneration. We then selected 5 cases of dVIN in which the clinical course and histopathology supported the diagnosis. We performed immunohistochemistry for p16 and p53 on all cases and did copy variant analysis on 1 case each of erosive LP and dVIN.

Histopathology of the LP cases showed epithelial thinning, absent stratum corneum, lack of maturation, as well as nuclear changes of enlargement, pleomorphism, and hyperchromasia. Three LP cases (60%) showed a wild-type p53 pattern and 2 (40%) were confluent positive. Two dVIN cases (40%) showed full-thickness loss of differentiation. One case (20%) of dVIN was p53 negative, 2 (40%) were wild-type, 1 was confluent positive, and 1 showed dark suprabasilar staining. All cases were negative for p16. Compared with control, erosive LP epithelium showed a similar copy-number pattern, whereas the dVIN epithelium had many copy-number changes.

A small subset of clinically diagnosed vulvovaginal erosive LP will show on histopathology a regenerative erosive vulvitis with loss of epithelial maturation and nuclear changes, which requires clinicopathologic correlation to distinguish from dVIN.