Discrepancies between clinical and histopathologic diagnoses in T3 pyriform sinus cancer.

The various ways in which pyriform sinus cancer extends to laryngeal structures were analyzed by whole-organ serial-sectioning. The problems regarding vocal cord fixation (T3) by this cancer are discussed. This study found that vocal cord fixation in pyriform sinus cancer is due mainly to the involvement of the intrinsic laryngeal muscles and not to the involvement of the arytenoid cartilage or the cricoarytenoid joint. A tumor originating in the medial wall tends to extend medially and to invade the intrinsic laryngeal muscles. This causes vocal cord fixation (T3) before classification as T2. However, a tumor originating in the lateral wall extends laterally beyond the thyroid ala (T4) with a mobile cord. Therefore, it is suggested that the T classification of the vocal cord fixation (T3) of pyriform sinus cancer may not reflect the actual cancer involvement.