Thanatophoric dwarfism and cloverleaf skull ("kleeblattschädel").

Four cases of thanatophoric dwarfism are presented, including 2 with an associated cloverleaf skull deformity (“kleeblattschadel”). Both entities are radiologically distinct. Distinguishing features of thanatophoric dwarfism include a narrow thorax and extremely short ribs, flat vertebral bodies, and an inverted “U” appearance of the spine on the frontal view. The skull may be enlarged or normal. The genetic implications of thanatophoric dwarfism and its relationship to cloverleaf skull deformity are unknown.