Head and Neck ImagingGlottic cancer
Squamous cell carcinoma head and neck is the most frequent
malignant tumour of the glottic larynx. There is a strong association with cigarette smoking. The presenting symptom is usually hoarseness. Tumoral involvement of the various laryngeal subsites and impairment of vocal mobility (as visible during clinical examination) determine the T-staging (see also
TNM classification head and neck).
Diagnostic imaging
Criteria used for tumour involvement are abnormal contrast enhancement, soft tissue thickening, presence of a bulky mass, infiltration of the fat in the paraglottic space, or a combination of these (Fig. 1). Any tissue thickening between the airway and the cricoid ring is considered to represent subglottic tumour extension. Small foci of mucosal tumour may be invisible on CT/MR images, and associated inflammatory and oedematous changes may cause overestimation of the tumour extent on CT/MR. Distortion of adjacent normal structures may mimic tumoral involvement.
Gross cartilage invasion can be detected with CT. Due to the large variability in the ossification pattern of the laryngeal cartilages, CT often fails to detect early cartilage invasion. Nonossified hyaline cartilage shows the same density values as tumour on CT images. Demonstration of tumour on the extralaryngeal side of the cartilage is a reliable, but late sign of cartilage invasion. Asymmetrical sclerosis, defined as thickening of the cortical margin and/or increased medullary density, comparing one arytenoid to the other, or one side of the cricoid or thyroid cartilage to the other side, is a sensitive but nonspecific finding at CT (Fig.1). Erosion or lysis has been found to be a specific criterion for neoplastic invasion in all cartilages. Other signs are not very reliable for cartilage invasion. CT appears to be more specific than MRI in the detection of neoplastic cartilage invasion, but seems to have a somewhat lower sensitivity, especially for thyroid cartilage involvement.
Treatment
Carcinoma in situ can often be controlled by stripping the vocal cord or with laser treatment. In T1 and T2 glottic cancers radiation treatment is usually preferred. Small volume T3 and T4 glottic cancers may be cured with either radiation treatment or total laryngectomy with possible postoperative radiation treatment. Large volume T3 and T4 cancers represent advanced disease and are advised to undergo total laryngectomy. CT (or MRI) is helpful in the selection of patients into a favourable group of T3 and T4 cancers, for whom there is a reasonable chance of cure by radiation therapy. Also, see radiation therapy tissue changes, baseline study and laryngectomy.
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Contrast enhanced axial CT images.
a. Level of true vocal cords. The left true vocal cord appears thickened and slightly enhancing. The tumour reaches the anterior commissure (arrow). The left paraglottic space is infiltrated (compare to normal opposite side (double arrowheads)). Marked sclerosis of the left arytenoid (single arrowhead). There appears to be some sclerosis of the left thyroid lamina. b. Level of subglottis. Enhancing soft tissue thickening on left side (double arrowhead). Note slight sclerosis of the cricoid arch on the left (single arrowhead). Slight enhancement is seen anteromedially to the subglottis, corresponding to subtle extralaryngeal tumour spread or peritumoral inflammation (arrow). The patient was treated surgically. Pathological examination confirmed glottic squamous cell carcinoma extending into the subglottic region without evidence of extralaryngeal tumour extension. The arytenoid showed focal neoplastic invasion; in the other cartilages only inflammatory changes were noted.
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Glottic cancer, Fig.1 (a) | | Glottic cancer, Fig.1 (b) | |