Tracheal cartilaginous sleeve.

Tracheal cartilaginous sleeve (TCS) is a rare congenital malformation in which discrete cartilaginous rings are replaced by a grossly uninterrupted cartilaginous sleeve. Seven previous patients with TCS have been reported in the world literature; in each instance, TCS was associated with craniosynostosis (CS). We report details of five additional patients with TCS, of whom four had a dominantly inherited CS. Gross examination of the available tracheas and bronchi demonstrates a cartilaginous sleeve with posterior interruption but lacking a normal pars membranacea. The stained and cleared tracheas all demonstrate variable ring formation, usually limited to the posterolateral aspect. The functional significance of TCS, if any, is unknown. No data are available on the prevalence of TCS in CS syndromes. The formation of TCS implies a common mesenchymal defect in which normally discrete structures fuse and is probably analogous to other mesenchymal abnormalities seen in these patients.