The role of mesenchyme-like tissue in the pathogenesis of thanatophoric dysplasia

In TD, areas of severely abnormal cartilage and bone alternated with less abnormal tissue. The severely abnormal areas were always found around protrusions of abnormal mesenchymal tissue that appeared to penetrate from the investing perichondrium and periosteum. Thus a basic pathogenetic mechanism in TD may be the persistence of abnormal fetal mesenchyme, which appears to transform into the severely abnormal bone and cartilage.