Differentiation of pyriform sinus cancer from supraglottic laryngeal cancer by computed tomography.

Nine pyriform sinus tumors and 16 supraglottic laryngeal lesions were studied by computed tomography. The pyriform sinus tumors had a much higher incidence of thyroid cartilage invasion (five of nine patients) and involved the posterolateral margins of the cartilage. Only two of 16 supraglottic tumors reached the thyroid cartilage, involving the midline or more inferior margins. The supraglottic tumors grew in a circumferential pattern, and when the pre-epiglottic space was involved, extension was bilateral. Lesions of the pyriform sinus more frequently showed unilateral involvement. Lymph node metastases were seen in an approximately equal proportion of patients in the two groups, and they correlated more with the size of the primary tumor than with its site of origin. Posteroinferior invasion of the space between the thyroid and cricoid cartilage was seen only with pyriform sinus lesions.