Previous studies have suggested that amplification of genes, notably theTOP2Agene, on chromosome arm 17q may be important for the development of malignant peripheral nerve sheath tumour (MPNST). In order to study the frequency, distribution, and chromosomal organization of rearrangements at 17q, interphase and metaphase fluorescencein situhybridization (FISH) were used to evaluate copy number changes at 17q in 28 MPNSTs. Increased copy numbers were seen for theERBB2andTOP2Agenes in eight and nine cases, respectively, supporting a potential role for these two genes in MPNST tumourigenesis. Net gain of distal 17q material was observed in 16 of the 28 MPNSTs, with high-level gain in three cases, and was associated with poor outcome. Among the 26 patients for whom follow-up data were available, gain of distal 17q was present in 11 of 12 tumours that had metastasized, compared with 4 of 14 of those that had not metastasized. Detailed FISH mapping analysis of metaphase spreads identified a 2 Mb commonly gained/amplified region at 17q25. Among the genes mapping to this region,BIRC5, which encodes the baculoviral IAP repeat-containing protein 5/survivin protein, is a strong candidate target gene for amplification, as it has been previously shown to be overexpressed in neurofibromatosis type 1-associated MPNST. Three other genes that co-amplified withBIRC5represent other potential candidate genes:PTDSRinvolved in apoptosis;SEPT9overexpressed in human malignant brain tumours; andSOCS3involved in cell survival and differentiation of neurons. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.