[Significance of the circumferential involvement of the superior horn tip of the thyroid cartilage in pharyngo-laryngeal cancer]

Abstract

The term "laryngopharyngeal carcinoma" indicates an advanced tumor involving both the supraglottic larynx and the pharynx in which the lesion origin may be difficult to assess. In 1981, Larsson et al. reported on the CT signs useful to distinguish the laryngeal/hypopharyngeal origin of advanced laryngopharyngeal carcinoma. We describe a new CT sign which may serve this purpose, namely the involvement of the thyroid cartilage superior horn tip. The thyroid cartilage superior horn, in fact, is involved early in the lesions originating in the pyriform sinus because of its close anatomic relationship with the posterolateral wall of the hypopharynx. MATERIALS AND METHODS. To assess the significance and specificity of this sign, we examined 15 patients with advanced laryngopharyngeal carcinoma with clinical, endoscopic and surgical evidence suggestive of tumors originating in the pyriform sinus. All CT examinations were performed with contiguous 4 mm slices before and after i.v. administration of iodinated contrast agents. Eighteen patients with surgically confirmed advanced supraglottic carcinoma were also examined.

Results: The thyroid cartilage superior horn tip was involved only in 3/18 supraglottic carcinoma patients; transcommissural infiltration of the larynx, involving both pyriform sinuses, was found in 2 of these cases and extensive invasion of the whole thyroid cartilage and of the cricoid ring in 1 case.

Conclusions: The thyroid cartilage superior horn tip is a reliable sign of the pyriform sinus origin of advanced laryngopharyngeal cancer which is both sensitive (100%) and specific (83%). Moreover, this sign could play a major role because it represents, in most cases, the only and earliest sign of cartilage involvement. Finally, the encasement of the thyroid cartilage superior horn tip by abnormal tissue indicates tumor spread beyond the posterior pharyngeal wall. Therefore, these data can be very important for its early detection and useful for subsequent surgical planning.