Ki-67 expression in vulvar carcinoma.

The proliferative activity of invasive squamous cell carcinoma of the vulva was examined using a Ki-67 equivalent monoclonal antibody (MIB1), which gives a strong immunoreaction in paraffin-embedded tissue. Quantitation of Ki-67 immunostaining was accomplished by image analysis. Ki-67 immunostaining revealed two general patterns of reactivity in vulvar tumors: (a) a diffuse distribution of Ki-67 positive nuclei within the tumor mass and (b) a localized distribution of Ki-67 positive nuclei staining predominantly basilar components of tumor aggregates. The distribution of localized and diffuse patterns did not differ significantly between various clinicopathologic categories (age, histologic type and grade, FIGO stage, and lymph node status). However, the survival times for patients with a diffuse Ki-67 labelling pattern tended to be shorter than those for patients with a localized pattern. Survival curves based on the median positive nuclear area (PNA) calculated by image analysis did not differ significantly. Thus, the pattern of Ki-67 immunostaining, rather than the percentage of PNA, may have prognostic significance in vulvar squamous cell carcinoma.