Near-haploidy in two malignant fibrous histiocytomas.

Cytogenetic analysis of two malignant fibrous histiocytomas (MFH) revealed near-haploid clones in both tumors. One tumor had only 23 chromosomes, the lowest chromosome number so far detected in human neoplasia, and showed several structural rearrangements: 23, X, der(1)t(1;?;8)(q42;?;q13), +del(7)(p11),der(8)t(8;13)(q13;q12), inv(9)(p24q21), r(10)(p15q26), -13, der(14)t(14;22)(p13;q11), -15, +r. The other MFH had only numerical changes: 28,X, +5, +18, +20, +21, +22/56, idemx2. With the present two cases, four of 78 MFHs studied in our laboratory have been near-haploid, suggesting that this otherwise rare phenomenon in neoplasia may be relatively common in MFH.