Page 156 - Atlas of Small Animal CT and MRI

Figure 1.11.6 Thyroid Carcinoma and Thyroid Adenoma (Canine) CT

12y FS Australian Shepherd with a right‐sided
ventral cervical mass. Ultrasound examination
revealed a large, solid vascular mass in the region
of the right thyroid lobe (a). A smaller hypoechoic
mass was seen within the body of the left thyroid
lobe (b). Unenhanced and contrast‐enhanced
transverse CT images (c–f) are paired and ordered
from cranial to caudal. A large right‐sided, uni-
formly contrast‐enhancing mass is present (c–f:
large arrow). The mass margin is poorly defined
(a) US, SP (b) US, SP ventrally, and there appears to be extracapsular
extension of the mass and diffuse enhancement
of adjacent tissues (e,f: arrowhead). A normal‐
appearing left thyroid lobe is seen on the more
cranial CT image (c,e: small arrow). On the more
caudal image, the left thyroid lobe is larger and
has lower attenuation characteristics than
expected, suggesting the presence of a second
smaller left thyroid mass (d,f: small arrow). CT
imaging findings are further documented on
long‐axis oblique axis reformatted CT images,
and now two small nodules are seen in the left
(c) CT, TP (d) CT, TP
thyroid lobe (h: small arrows). Imaging findings
were corroborated at the time of surgical excision
(i,j: arrows). Excisional biopsy revealed right‐
sided thyroid carcinoma with extracapsular inva-
sion and left‐sided thyroid adenoma.

(e) CT+C, TP (f) CT+C, TP

(g) CT+C, OP (h) CT+C, OP

(i) GP (j) GP
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