Trisomy 20 is a primary chromosome aberration in desmoid tumors

Chdtogenetic analysis revealed trisomy 20 in 4 desmoid tumors: in 2 cases as the sole aberration, in hd together with +X, ‐Y and −13 and in I with +8 and a supernumerary marker chromosome. Our findings indicate that gain of chromosome 20 is an early event in the development of a large subset of desmoid tumors and that it is as frequent as +8, the only consistent chromosomal change previously reported in this tumor type. The non‐random occurrence of trisomies 8 and 20 in desmoid tumors indicates shared pathogenetic mechanisms with infantile fibrosarcoma, a fibrous tissue tumor characterized by various combinations of trisomies for chromosomes 8, 11, 17 and 20.