Whereas the chondroma displayed the relatively simple karyotype 46,XY,add(12)(q13),der(17)t(12;17)(q13;q21), more complex changes were found in the three cases of chondromatosis: case 1, 47,XY,der(1)inv(1)(p13q25)del (1)(q25q32), t(1;12)(q25;q13), + 5,der(12)add(12)(p11)t(1;12)(p22;q13); case 2, 47,XY,add(10)(q26), + 20/46 idem,-6/46,XY,t(2;4)(q33;q21), add(21)(p11); and case 3, 44,XY,add(1)(p36), del(1)(p13p22),add(6)(p25), del(7) (q22q32),del(10)(q21),add(11)(q13),-17,-18.