Flow and image cytometry in thymic neoplasia - Correlation with clinical outcome

OBJECTIVE: To compare nuclear DNA by flow (FCM) and image cytometry (ICM) i n thymic neoplasms and to relate results to clinical outcome. STUDY DESIGN. DNA ploidy of 44 thymomas and 6 thymic carcinomas was studied by FCM and ICM of single nuclear suspensions from paraffin blocks. RESULTS: By FCM, 33 thymomas (75%) and one thymic carcinoma (17%) were dipl oid; 6 thymomas (14%) and 4 thymic carcinomas (67%) were aneuploid. By ICM, 36 thymomas (82%) were diploid; 7 thymomas (16%) and 6 thymic carcinomas ( 100%) were aneuploid. Mean follow-up in 44 cases was 46.2 months (range, 1- 162). Ten patients with persistent/recurrent disease included four with thy mic carcinoma, who died of the disease (two aneuploid by both techniques, t wo aneuploid by ICM with unsatisfactory/diploid FCM). Four had invasive thy moma and recurrence after 13-150 months (two diploid and two aneuploid by b oth methods), one had diploidy and noninvasive thymoma that recurred at 92 months, and one had an epithelial thymoma that recurred at 144 months (aneu ploid by FCM, diploid by ICM). CONCLUSION: The results obtained in this preliminary, retrospective study s how a high concordance between FCM and ICM; aneuploidy correlated with poor outcome by both methodologies. While these findings are encouraging, large r numbers of cases will be needed to define the role of FCM and ICM in pred icting outcome in thymic tumors.