Page 681 - Atlas of Small Animal CT and MRI

Neoplasia 671

Figure 6.4.8 Feline Injection Site Sarcoma (Feline) CT

(a) CT, TP (b) CT+C, TP (c) CT+C, SP
6y MC Domestic Longhair with a large left pelvic limb mass. There is a large heterogeneously hypoattenuating mass arising from the proxi-
mocaudal aspect of the left pelvic limb, which is obliterating normal muscle anatomy (a). The mass heterogeneously and peripherally
enhances following intravenous contrast administration (b,c). Microscopic evaluation showed a neoplastic cell population consistent with
myxosarcoma, with small‐caliber vessels surrounded by dense aggregates of lymphocytes and plasma cells. A diagnosis of feline injection
site sarcoma was based on the combination of characteristic pathology findings, patient age, vaccination history, and lesion location.

Figure 6.4.9 Malignant Peripheral Nerve Sheath Tumor (Canine) CT

(a) CT, TP (b) CT+C, TP (c) GP, MED
6y FS Labrador Retriever with a 1.5‐month history of right thoracic limb lameness. Images a and b are comparable unenhanced and
contrast‐enhanced CT images, respectively, acquired at the level of the radial head and olecranon near the proximal extent of the mass.
There is a well‐delineated globoid mass arising from the medial side of the limb and encroaching on the elbow joint (a: asterisk). The
mass heterogeneously enhances following intravenous contrast administration (b: asterisk) and appears to encircle the elbow joint
caudolaterally (b: arrow). The limb was amputated, and the mass was determined to be a malignant peripheral nerve sheath tumor that
extended most of the length of the antebrachium (c: arrowheads). On gross inspection, the mass effaced adjacent musculature but did
not invade the joint.

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