IHC previously performed at the time of diagnosis showed S-100 reactivity in 61% of MPNST, with 13% of samples being immunoreactive in more than 20% of cells, and 48% of specimens displaying staining in scattered cells (data not shown); all tumors were nonreactive for cytokeratins and epithelial membrane antigen (data not shown). This evidence concerns the gene MUC1 and malignant peripheral nerve sheath tumor.