Analysis of alterations adjacent to invasive vulvar carcinoma and their relationship with the associated carcinoma: a study of 67 cases.

A retrospective analysis of histological lesions adjacent to 67 invasive vulvar squamous cell carcinomas (SCC) was undertaken to analyse their nature, as well as their relationship to SCC. Patient age, clinical presentation and histological type of carcinoma, ISSVD classification of its adjacent lesions, disease-free and overall survival were reviewed. Severe undifferentiated vulvar intra-epithelial neoplasia (VIN3) was found in 19.4% of cases and vulvar lichen sclerosus (VLS) in 76.1% of cases. All VLS, except 2 cases, were associated with squamous cell hyperplasia (SCH), and a concomitant differentiated VIN was found in 76.6% of cases. Undifferentiated VIN3 was never associated with VLS. VLS was significantly associated with a keratinizing, well-differentiated SCC (98% of cases), while undifferentiated VIN3, was linked preferentially to 2 other types of SCC: in 77% of cases, a moderately-differentiated SCC with the same histological features as the so-called basaloid carcinoma and, in 23% of cases, a well-differentiated SCC with a variable extent of koilocytic atypia, similar to the so-called warty carcinoma. Carcinoma of the fourchette was more often associated with undifferentiated VIN3. Disease-free and overall survival were significantly better for carcinoma associated with undifferentiated VIN3 (p < 0.01 and p < 0.05, respectively). These findings suggest invasive vulvar SCC occurs on 2 distinct types of vulvar lesions: differentiated VIN and/or SCH associated with VLS and undifferentiated VIN3. Furthermore, the histological type of the carcinoma seems to differ according to adjacent lesions.