Computer-assisted cytogenetic analysis of 51 malignant peripheral-nerve-sheath tumors: Sporadic vs. neurofibromatosis-type-1-associated malignant schwannomas

Cytogenetic studies in small groups of patients with malignant peripheral-n erve-sheath tumors (MPNST) revealed complex karyotypes with no consistent c hanges. A computer-assisted cytogenetic analysis using a cytogenetic databa se was performed to determine recurrent cytogenetic alterations in 51 MPNST s (44 from the literature and 7 new cases) and to allow direct cytogenetic comparison between NF-l-associated and sporadic MPNSTs. Significant loss (p < 0.05) was observed in the chromosomal regions 9p2, 11p1, 11q2 and 18p1. Also, loss in 1p3, 9p1, 11q1, 12q2, 17p1, 18q1-q2, 19p1, 22q1, X and Y was detected. Gain of chromosomal material was found in chromosome 7, especiall y 7q1 (p < 0.05). Most involved breakpoints were: 1p13, 1q21, 7p22, 9p11, 1 7p11, 17q11, 22q11. Cytogenetic differences between NF-I-associated and spo radic MPNSTs included a relative loss of chromosomal material in NF-I-assoc iated MPNSTs in 1p3, 4p1 and 21p1-q2 and a relative gain in 15p1-q1. Differ ences in breakpoints between the NF-I associated and the sporadic MPNST gro up were observed in 1p21-22 (28% of NF-I vs. 0% of sporadic MPNSTs), 1p32-3 4(17% vs. 0%), 8p11-12 (7% vs. 27%) and 17q10-12 (24% vs. 7%). This approac h, in which the cytogenetic results of various reports are combined, shows that losses in 9p2 and gains in 7q1 could be of oncogenetic importance in M PNSTs. Lass of 17q1, on which the NF-I gene has been located (17q11.2), is not a common cytogenetic finding in NF-I-associated MPNSTs. The observed di fferences between NF-I-associated and sporadic MPNSTs might reflect differe nt oncogenetic pathways. (C) 1999 Wiley-Liss, Inc.