Page 75 - Atlas of Small Animal CT and MRI

Figure 1.4.14 Multilobular Osteochondrosarcoma (Canine) CT & MR

(a) T2, TP (b) T1, TP (c) T1+C, TP

(d) T1+C, SP (e) CT, SP (f) CT, TP

(g) T1+C, DP
7y FS Golden Retriever with a recent history of progressive incoordination. Neurologic examination localized neurologic deficits to the
brainstem. A spherical mass arises from the occipital bone, causing extensive occipital osteolysis, and extends both intracranially and
extracranially. The mass is hypointense on the unenhanced T1 image (b), has heterogeneous intensity and perilesional edema on the T2
image (a), and intensely and nonuniformly contrast enhances (c,d,g). The intracranial component of the mass is predominantly within
the caudal fossa, causing rostral cerebellar displacement (d: large arrow), cerebellar and brainstem compression (d: small arrows), and
obstructive hydrocephalus (d,g). The rostrodorsal aspect of the mass also encroaches on the caudal aspect of the rostral fossa, compressing
the occipital lobes (d,g: arrowheads). Occipital osteolysis is also appreciated on the CT images (e). The coarse, granular, and diffuse
mineralization (e,f) is characteristic of multilobular osteochondrosarcoma. Excisional biopsy confirmed the diagnosis of multilobular
osteochondrosarcoma.

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