Chondromatous metaplasia in the human larynx.

The finding of metaplastic fibroelastic cartilage in both vestibular folds of the larynx of an Orang-utan (Pongo pygmaeus) prompted the search for similar tissue in the same situation in 111 unselected human larynges removed at autopsy. Fibroelastic cartilage was found in both vestibular folds in three cases, being unilateral in a further four instances. The formation of this cartilage was preceded by the accumulation of acid mucopolysaccharide between fine collagen bundles within the vestibular fold followed by enlargement and alteration of the fibrocytes to resemble chondrocytes. These changes were found in 43 vestibular folds, and were bilateral in 10 cases.