Persistence of injectable collagen in the human larynx: a histopathologic study

This is a report of the histologic findings in a human larynx that had undergone collagen injection for glottic insufficiency 14 months prior to autopsy. The patient's management before augmentation with collagen included extended supraglottic laryngectomy, radiation therapy, and Polytef injection. Connective tissue changes secondary to other forms of treatment were apparent bilaterally and changes limited to the site of collagen injection were identified. There have been reports of persistence of injected collagen in the canine larynx at 1 year but this is the only study documenting persistence in a human subject. The implant appeared homogeneous and was easily distinguished from host collagen and the reactive fibrosis associated with particulate Polytef. These findings are similar to those observed in the canine model and suggest that there is persistence of injected collagen in the human larynx.