CYTOGENETIC ANALYSIS OF 46 PLEOMORPHIC SOFT-TISSUE SARCOMAS AND CORRELATION WITH MORPHOLOGIC AND CLINICAL-FEATURES - A REPORT OF THE CHAMP STUDY-GROUP

With the aim of identifying objective cytogenetic-morphologic correlat ions, we evaluated 46 pleomorphic soft tissue sarcomas (mainly diagnos ed originally as malignant fibrous histiocytomas) with clonal chromoso me aberrations both cytogenetically and morphologically as part of an international collaborative study. By detailed histopathologic examina tion, most cases could be categorized into specific tumor types. Eight sarcomas were diagnosed as lipogenic (4 pleomorphic, 1 combined pleom orphic and myxoid/round cell, and 3 dedifferentiated liposarcomas), 19 as myogenic [11 leiomyosarcomas, 1 rhabdomyosarcoma, 4 myosarcomas no t otherwise specified (NOS), and 3 probable myosarcomas NOS], 8 as myx ofibrosarcomas, 1 as a malignant peripheral nerve sheath tumor, 1 as m alignant mesenchymoma, 1 as extraskeletal osteosarcoma, 1 as sarcoma r esembling proliferative fasciitis, and 7 as pleomorphic sarcomas NOS. In a three-grade system, IO tumors were grade 2 and 36 were grade 3. T he majority had highly complex karyotypes. A total of 24 recurrent abn ormalities (defined by their presence in at least five cases) were det ected: ring chromosomes, homogeneously staining regions (hsr) and/or d ouble minute chromosomes (dmin), and structural rearrangement of 22 di fferent chromosome bands or regions. The frequency and distribution of the recurrent karyotypic features were uneven. Grade 3 tumors display ed, on average, more aberrations per case than did grade 2 tumors. Nin e of the selected abnormalities, including hsr/dmin and rearrangements of 19p13 and 19p13, were found only among the high-grade tumors. When the rumors were subdivided according to lineage of differentiation, t he highest frequency of aberrations was seen in pleomorphic sarcomas N OS, followed by myxofibrosarcomas, myogenic sarcomas, and lipogenic sa rcomas. None of the selected rearrangements was, however, specific for any of these subgroups, The sole consistent cytogenetic-morphologic a ssociation was that all three dedifferentiated liposarcomas had multip le abnormal clones, at least one of which contained supernumerary ring chromosomes. Due mainly to karyotype complexity, it therefore seems u nlikely that cytogenetic analysis can assist in the differential diagn ostic subclassification of pleomorphic sarcomas, nor was there any cle ar-cut indication that the karyotypic picture could be used to predict clinical outcome. Although the mean number of recurrent chromosome ab errations was almost twice as high in sarcomas that gave rise to metas tases as among those that did not, no particular aberration was restri cted to either of the two subgroups. (C) 1998 Wiley-Liss, Inc.