Expression of Ki-67 in vulvar carcinoma and vulvar intraepithelial neoplasia III: correlation with clinical prognostic factors.

OBJECTIVES

In vulvar carcinoma, the expression of Ki-67 has been previously found to correlate with patient outcome. The objective of the study was to determine whether a specific pattern of expression was associated with occult vulvar cancer in patients with vulvar intraepithelial neoplasia (VIN) III and whether patterns of Ki-67 expression correlated with other clinical prognostic factors.

METHODS

19 women with only VIN III, 16 women with both vulvar cancer and VIN III, and 15 women with only vulvar cancer were identified. Immunostaining, using a monoclonal antibody for Ki-67, was then performed on representative tissue blocks and slides were assessed for diffuse or localized patterns of expression. For the patients with vulvar cancer, the type of staining was correlated with FIGO stage, tumor grade, lymph nodes status, and associated VIN III.

RESULTS

All 35 patients with VIN III exhibited a diffuse staining pattern. In the 31 patients with vulvar carcinoma, 11 (35%) expressed a diffuse staining pattern while 20 (65%) showed a localized pattern. Poorly differentiated tumors were associated with a diffuse staining pattern (P = 0.013, RR 3.59, CI 1.59-7.60). For vulvar carcinoma, there were no statistically significant relationships between Ki-67 expression pattern and stage, associated VIN III, or lymph node involvement.

CONCLUSION

VIN III, regardless of a concomitant vulvar cancer, always expressed a diffuse pattern; thus Ki-67 staining was not useful as a marker for occult cancer. In women with vulvar carcinoma, however, a diffuse Ki-67 expression was significantly associated with poorly differentiated tumors.