Effusion cytodiagnosis of carcinosarcoma derived from the female genital tract: immunohistochemical features of MMP-7 and Ki-67 and immunofluorescence double staining analyses of eight cases.

OBJECTIVE: Expression of Matrix metalloproteinase 7 (MMP-7) and Ki-67 by carcinoma components (CCs) and sarcoma components (SCs) in carcinosarcoma of the female reproductive organs has been investigated by conventional methods, but analysis with immunohistochemical staining of multiple antigens has not been reported. We report the profiles of expression of MMP-7 and Ki-67 in carcinosarcoma determined with immunohistochemical staining techniques.
METHODS: We used antibodies against epithelial antigen (EA), epithelial membrane antigen (EMA), and vimentin for immunofluorescence double staining of ascitic fluid in eight cases of carcinosarcoma of female reproductive organs. We also used immunohistochemical triple staining to compare MMP-7 and Ki-67 expression between CCs and SCs in the primary site of carcinosarcoma.
RESULTS: Immunofluorescence analysis revealed that all neoplastic cells in the ascitic fluid were positive for EA or EMA, indicating that these cells were CCs. Immunohistochemical analyses of the primary organ of carcinosarcoma revealed that MMP-7 was expressed on CCs in four of eight cases of carcinosarcoma, whereas MMP-7 was not expressed on SCs. The average Ki-67 labeling index (LI) in CCs and SCs was 51.8% and 28.6%, respectively. The difference in Ki-67 LI between CCs and SCs was statistically significant (t test for paired samples, P = 0.0173).
CONCLUSIONS: This is the first study to examine carcinosarcoma of the female reproductive organ by immunohistochemical staining for multiple antigens, which allows analysis of mixed tumor elements. In addition, we found that expression of MMP-7 and the average Ki-67 LI differ between CCs and SCs in carcinosarcoma. The predominance of CCs as the malignant cells in the ascitic fluid may be due to cytological differences between CCs and SCs of carcinosarcoma.