Flow cytometric DNA ploidy analysis of soft tissue sarcomas. A comparative study of preoperative fine needle aspirates and postoperative fresh tissues and archival material

Flow cytometric (FCM) DNA ploidy measurements on frozen fresh samples of soft tissue sarcomas were compared with the corresponding analyses on preoperative fine needle aspirates and postoperative formalin-fixed archival tissues from the same tumors. A concordance in ploidy status (diploid versus non-diploid) was obtained for 63% of the fresh tissue-fine needle aspiration (FNA) sample comparisons and for 85% of the fresh tissue-archival material comparisons. The majority of discordances in the fresh tissue-FNA sample comparisons could be explained by FNA sampling errors. In the remaining discordant cases (3 of 27 FNA sample comparisons and 6 of 40 archival material comparisons), sampling errors could not explain the differences in ploidy status. The discordant cases were evenly distributed among the different sampling methods. Method reproducibility was not responsible for the differences in ploidy determinations; tumor heterogeneity may be an explanation for the discrepancies. This study showed that archival soft tissue sarcoma samples are as well suited for DNA ploidy analysis as are fresh frozen tissues.