We report the cytogenetic findings of two cases of fibrous dysplasia,
one occurring in the tibia, the other in the sphenoid. Both cases exhi
bited only one chromosome change: a t(6;11)(q15;p15) in the first case
, a derivative chromosome 2 in the second. The previous cytogenetic re
port on fibrous dysplasia revealed only numerical changes. The signifi
cance of these inconsistent chromosomal findings in fibrous dysplasia
is unclear.