Chromosomal changes in mature residual teratomas following polychemotherapy.

A cytogenetic analysis of 13 mature residual teratomas following chemotherapy revealed modal chromosome numbers ranging from 52 to 85, in agreement with the flow cytometric determination of the DNA content of the tumors. At least one copy of an i(12p) was present in 12 tumors. One tumor, however, lacked that marker. The comparison between the chromosomal abnormalities found in mature residual teratomas following chemotherapy and those from primary testicular nonseminomas suggests that residual teratomas result from selection of clones from the primary tumor with a less abnormal karyotype.