A NEW CYTOGENETIC SUBGROUP IN LIPOMAS - LOSS OF CHROMOSOME-16 MATERIAL IN SPINDLE-CELL AND PLEOMORPHIC LIPOMAS

Six spindle cell lipomas and two pleomorphic lipomas were analyzed cyt ogenetically, One spindle cell lipoma had a supernumerary ring chromos ome as the sole anomaly. The other five spindle cell lipomas and both pleomorphic lipomas had hypodiploid stemlines with monosomy 16 or unba lanced aberrations leading to loss of 16q13-qter, a feature distinguis hing these lipoma subtypes from other benign and borderline adipose ti ssue tumor histotypes. Unbalanced aberrations of chromosomes 13 and 10 were found in five and three cases respectively; 13q12 was lost in al l of these cases, whereas there was no common deleted segment in chrom osome 10. No aberrations involving 12q13-15, which are frequent in typ ical lipomas, were found, Both pleomorphic lipomas, but none of the sp indle cell lipomas, had hypotetraploid sidelines, multiple nonclonal a berrations, and telomeric associations. The present findings reveal a new cytogenetic/histopathological association in adipose tissue tumors .