Head and Neck ImagingSubglottic cancer
rare
malignant lesion. Histologically, these lesions are
squamous cell carcinomas head and neck, but
adenoid cystic carcinoma is also frequently located at this level. By the time of diagnosis, subglottic cancer has usually invaded the true vocal cords, and it may be difficult to distinguish between a cancer originating in the glottis or subglottis. Subglottic cancer is commonly bilateral or even circumferential at presentation. Cricoid
cartilage invasion occurs early; extralaryngeal extension, anteriorly through the cricothyroid membrane or inferiorly into the trachea, is also commonly present. Lymphatic dissemination is seen in about 10% of cases; among the
lymph nodes which may become involved are the
Delphian node and paratracheal
lymph nodes.
Imaging shows a subglottic soft tissue mass (normally no soft tissue is seen between the subglottic air column and the cricoid cartilage), and the findings may include cricoid cartilage alterations (sclerosis, lysis), intratracheal soft tissue tickening, and infiltration of the glottic and prelaryngeal soft tissues (Fig.1). Imaging is important to determine the margins of the lesion for surgical and radiation treatment.
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Axial contrast-enhanced CT images of larynx.
a. Anterior subglottic soft tissue thickening, with bilateral posterior spread along the subglottic wall (small arrowheads). Extralaryngeal spread through the cricothyroid membrane (arrow). Centrally hypodense nodule presumably corresponds to necrotic Delphian node (large arrowhead).
B. Section 9 mm cranial to a. The soft tissue mass extends into the anterior commissure and both true vocal cords. Some sclerosis (arrows) and lysis of the thyroid cartilage (arrowhead) is visible. Squamous cell carcinoma.
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Subglottic cancer, Fig.1 (a) | | Subglottic cancer, Fig.1 (b) | |