Morphologic and biologic studies on ten cases of verrucous carcinoma of the vulva supporting the theory of a discrete clinico-pathologic entity.

Ten cases of verrucous carcinoma (VC) of the vulva diagnosed from January 1989 to December 1996 were studied. Patient age ranged from 50 to 83 years. The following examinations were performed on buffered formalin-fixed material: 1). in situ DNA hybridization, probes HPV 6/11, 16/18, 31/35/51; and 2). a series of immunohistochemical stainings to demonstrate wild and mutant types of the p53 protein, cytokeratin expression and pattern distribution (AE1 and AE3), and proliferating pattern (MIB 1). In situ DNA hybridization analysis for human papillomavirus 6/11, 16/18, 31/35/51 was negative in all cases. Wild and mutant types of p53 protein transcribed from related oncosuppressor gene were not detected. Keratins AE1 and AE3 showed a peculiar distribution pattern, that is, AE1 was uniformly positive in the surface and intermediate layers, while it was almost negative in the basal layer which-on the contrary-was mainly positive to AE3 keratins. MIB-1 highlighted 10-40% of proliferating cells; however, in all cases, 70-80% of MIB-1 positivity was found in the basal layer of the neoplastic epithelium. These results seem to show the morphofunctional and growth characteristics of neoplastic epithelium, thus stressing that VC should be considered as a discrete entity in vulvar tumors.