Malignant peripheral nerve sheath tumor with a t(X;18) - A synovial sarcoma variant?

We describe an ankle tumor arising in a 16-year-old girl. The tumor demonst rated histology typical of a malignant peripheral nerve sheath tumor (MPNST ), but exhibited a variant form of the (X;18) translocation associated with synovial sarcoma. Immunohistochemical stains were positive for vimentin, C D57, collagen type IV, and Bcl-2. Routine and molecular cytogenetic studies showed an unbalanced 3-way chromosomal translocation that involved chromos omes X, 18, and 1. Electron microscopic findings were noncontributory. This unusual tumor raises the following questions and possibilities: (1) As the t(X;18) suggests, could this tumor be a monophasic synovial sarcoma with t he histologic features of an MPNST? (2) Or, as the histology suggests, is t his tumor an MPNST that has a t(X;18)? (3) Finally, could MPNST histology, a t(X;18), and no defining immunohistochemical or electron microscopic feat ures represent an as yet unrecognized part of a spectrum that spans from sy novial sarcoma to MPNST or other spindle cell tumors?