Testicular seminomas are aneuploid tumors.
BACKGROUND
Distinct ploidy patterns of germ cell tumors and aneuploidy of classic seminoma are of central importance in a current concept designating seminoma as a stage in tumor evolution preceding all nonseminomatous germ cell tumors. Whereas cytogenetic studies almost constantly revealed numerical chromosomal aberrations in seminomas in line with this pathogenetic model, ploidy determination by DNA cytometry yielded highly controversial results on the frequency of diploid seminomas.


METHODS
Twenty-two classic seminomas were investigated in a comparative manner by DNA flow and DNA image cytometry on nuclei isolated from fresh as well as formalin-fixed tumors. The cellular composition of the tumors, i.e., the number of neoplastic, interstitial, and lymphoid cells was quantified in each case.


RESULTS
Irrespective of the tissue preparation and fixation method, all of the tumors that were analyzed were aneuploid by image cytometry. Diploid cases were only found by flow cytometry. Thus, 1/22 cases from paraffin-embedded and 4/11 cases of native tumors showed a single diploid stemline by flow cytometry, however, they exhibited aneuploidy by image cytometry. The quantity of tumor infiltrating lymphocytes was clearly correlated with false diploidy detected by flow cytometry.


CONCLUSIONS
Classic testicular seminomas are aneuploid tumors. Previous reports on diploid cases detected by flow cytometry have most likely been caused by extensive lymphocytic infiltration.
Hittmair
A
A
Department of Pathology, University of Innsbruck, Austria.
Rogatsch
H
H
Feichtinger
H
H
Hobisch
A
A
Mikuz
G
G
D000782:Aneuploidy; D004273:DNA, Neoplasm / Q000032:analysis*; D005434:Flow Cytometry; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D018239:Seminoma / Q000235:genetics*; D013736:Testicular Neoplasms / Q000235:genetics*
D004273:DNA, Neoplasm