CORRELATION BETWEEN CLINICOPATHOLOGICAL FEATURES AND KARYOTYPE IN LIPOMATOUS TUMORS - A REPORT OF 178 CASES FROM THE CHROMOSOMES AND MORPHOLOGY (CHAMP) COLLABORATIVE STUDY-GROUP

Soft tissue tumors commonly show cytogenetic abnormalities, some of wh ich are tumor specific. Lipomatous tumors represent the largest catego ry of soft tissue neoplasms, and numerous karyotypic aberrations have been identified. However, clear-cut correlation between morphology and karyotype has not been undertaken on a systematic basis in a double-b lind setting. The morphological features and histological diagnosis of 178 lipomatous neoplasms were reviewed independently without knowledg e of the clinical data. The consensus diagnoses were then correlated w ith the clinical findings and compared with the tumors' karyotypes, us ing G-banded preparations from short-term cultures. The data were coll ated by a multicenter collaborative group of pathologists, geneticists , and surgeons. Clonal chromosomal abnormalities were identified in 14 9 cases studied (84%) and, to a large extent, the karyotype correlated with the morphological diagnosis. Specifically, 26 (96%) of 27 myxoid liposarcomas and its poorly differentiated variants showed at t(12;16 ); 29 (78%) of 37 atypical lipomatous tumors (including 5 dedifferenti ated cases) showed ring chromosomes; 74 (80%) of 93 subcutaneous and i ntramuscular lipomas had karyotypic aberrations affecting mainly 12q, 6p, and 13q; 7 of 8 spindle cell and pleomorphic lipomas had aberratio ns of 16q; 3 lipoblastomas showed 8q rearrangements; and 2 hibernomas showed 11q abnormalities. We conclude that cytogenetic abnormalities a re common in lipomatous tumors, correlate reliably with morphological subtype in many cases, and can be of diagnostic value in histologicall y borderline or difficult cases.