A cytogenetic study of malignant fibrous histiocytoma.

We report the results of cytogenetic analysis of malignant fibrous histiocytoma of soft tissue (MFH). Seven of 12 successfully cultured MFHs had complex clonal aberrations, including translocations, deletions, and unidentifiable marker chromosomes. Telomeric associations were observed in five and the double minute phenomenon in four of seven MFHs with abnormal karyotypes. In one case (a storiform-pleomorphic MFH, grade IV) with a complex polyploid karyotype, two clonal ring chromosomes were present, one interpreted as r(19)(p13q13), one unidentified. In two tumors, clonal structural rearrangements of chromosome 1 were seen: del(1)(q21) in a storiform-pleomorphic MFH, grade IV, and add (1)(q21 or q32), t(1;10)(p22;q22) in a myxoid MFH, grade I. The remaining five MFHs had normal karyotypes, but in two of them nonclonal, structural aberrations were found. The modal chromosome number in the studied MFHs varied widely, but the majority of tumors with abnormal karyotypes had polyploid chromosome complements (five of seven cases). Our results confirm many of the previous findings and indicate that double minutes (dmins) may be more frequent in MFH than previously reported.