Page 143 - Atlas of Small Animal CT and MRI

Larynx, Pharynx, and Neck 133

hypoattenuating on CT or hyperintense on T2 on MR, The larynx, tonsils, and pharynx may be affected by
with strong peripheral contrast enhancement (Figures oral tumors, such as fibrosarcoma or squamous cell
1.10.5, 1.10.6). Fistulography may be considered to carcinoma involving the soft palate or tongue (see
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define any draining tracts and to attempt to outline the Chapter 1.9, Figure 1.9.17 and Figure 1.10.10). Round
foreign body. cell neoplasia may also arise in these soft tissues and
cause nasopharyngeal obstruction and local lymph node
Neoplasia enlargement (Figures 1.10.11, 1.10.12).

Ectopic thyroid neoplasia has been recognized to occur
in the laryngeal region, with possible invasion of the Idiopathic and other disorders
laryngeal lumen or ventral musculature. Masses are
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oval or bilobed and are centered on the basihyoid bone Upper airway obstruction may occur secondary to
with osteolysis (Figure 1.10.7), and normal thyroid laryngeal paralysis or laryngeal collapse. On CT images,
glands are present. Metastasis to local lymph nodes or the imaging findings of laryngeal paralysis include
the lungs may occur. Primary thyroid neoplasia is failure to abduct the arytenoid cartilages, air‐filled
discussed in Chapter 1.11. lateral ventricles, and a narrowed rima glottis. Everted
The musculature of the larynx may also give rise to laryngeal saccules, collapse of the cuneiform and cor-
neoplasia, such as rhabdomyoma or rhabdomyosarcoma niculate processes, and narrowed rima glottis were seen
(Figure 1.10.8). Neuroendocrine tumors, such as carotid in sedated dogs with laryngeal collapse. These features
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body tumors, also occur in the region of the larynx and may be difficult to assess in animals that are intubated
may be mistaken for thyroid carcinoma (Figure 1.10.9). 10 under general anesthesia.

Figure 1.10.1 Hyoid Trauma (Canine) CT

(a) CT, TP (b) CT, TP
5y FS Jack Russell Terrier with a 3‐month history of coughing, gagging, and nasal discharge. Images a and b are the same image with
and without annotation. These are 5 mm collimated transverse images that include the basihyoid bone (b: arrowhead), caudal ends of the
ceratohyoid bones (b: small arrows), portions of the epihyoid bones (b: large arrows), and the distal end of the left stylohyoid bone (b: black
arrow). The caudal end of the angular process of the right mandible is also seen (b: black arrowhead). The right epihyoid bone is displaced
laterally, indicative of trauma.

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