On the basis of embryology and clinical experience, we have defined here an anterior commissure (AC) subsite of the human larynx and have addressed the issue as to whether the degree of involvement of this subsite is related to the outcome of glottic cancer, in terms of local control within 5 years of therapy. Retrospective analysis of 534 patients included 1) classification of patients according to the TNM, 2) actuarial evaluation of the outcome, 3) reclassification of patients according to the involvement of the AC subsite, and 4) reevaluation of the outcome according to this latter classification. The results showed that the outcome was not well correlated with TNM classification, whereas patients with progressively heavier involvement of the AC subsite had a progressively worse outcome. On the basis of these data, we suggest that TNM classification of cancer involving the AC be implemented by and AC classification, in order to better forecast the prognosis and design specific conservative surgery.

In this study we attempt to define the organization of the anterior region of the adult larynx, on the basis of its development. For this purpose, we have studied the development of the anterior commissure region on serial sections of human larynges from embryos, fetuses, and adults. Our findings indicate that all the structures of this region derive from a single median mesenchymal band, first evident at 7 to 8 weeks of gestation, between the lateral laminae of the thyroid cartilage. This band of mesenchyme gives rise to all the structures along the midline of the thyroid cartilage and immediately beyond, including the intermediate lamina of the thyroid cartilage, the median process, and the connective tissue that connects the latter with the conoid ligament. We provide, for the first time, evidence that Broyles' ligament (commissural tendon) derives from the dorsal part of the median process and becomes intimately connected with the surrounding structures, including the insertion fibers of the vocal muscles, from early in development. On the basis of this finding we identify an independent anterior commissure region in the adult larynx, which comprises the intermediate lamina, Broyles' ligament, the connective tissue between the Broyles' and conoid ligaments, and the insertion fibers of the vocal muscles. The interpretation of all these structures as a unified region can explain the peculiar progression pathways and evolution of commissural and cordo-commissural tumors.

The TNM classification is unsatisfactory regarding the impaired mobility of the vocal cord and/or the arytenoid. The authors have studied the intrinsic laryngeal musculature, with particular attention to the medial thyroarytenoid muscle, the lateral thyroarytenoid muscle, and the inferior paraglottic space. The study was conducted on serial sections of 4 embryonal and 9 fetal larynges at different stages of development. The embryological observations showed that the lateral and medial thyroarytenoid muscles have different maturation times and probably different functions: phonatory and sphincteric. The authors have found that the inferior paraglottic space is situated between these 2 muscles. It would represent a path of diffusion for glottic cancer and play a central role in impaired vocal cord and/or arytenoid mobility, according to the degree of diffusion. Embryological observations have suggested the existence of laryngeal morphofunctional units belonging to the subsites of the glottic region and related to tumoral spreading.