Page 692 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

670 PART IV Specific Malignancies in the Small Animal Patient

lumbar plexi, the classic clinical scenario is one of chronic lame- ST of 8 months. 170 The prognosis for cats is more favorable. In
ness without identifiable orthopedic abnormalities. 163,164 The eti- one study of 45 surgically treated cats, 31% (5/16) of MPNST
158
recurred compared with 14% (4/43) of BPNST.
Treatment
ology of the observed clinical signs may remain elusive for months
VetBooks.ir and may not be appreciated until signs progress to monoparesis failures typically manifest as neurologic signs attributed to local
recurrence.
with neurogenic atrophy or signs of spinal cord disease appear.
Signs of myelopathy are often asymmetric and occur when the Canine trigeminal PNST may have an insidious clinical
mass invades the vertebral canal and compresses or invades the course, with some untreated dogs experiencing STs in excess of
SC. Clinical signs of pain on palpation or paresthesia are also 18 months without significant clinical progression. 160,167,171
common. Trigeminal PNSTs may be surgically removed or irradiated and
Trigeminal PNSTs cause signs of severe, unilateral masticatory successful outcomes have been reported for both treatment
muscular atrophy, diminished jaw tone, decreased facial sensation, modalities. 160,167,171 The MSTs for dogs with trigeminal PNST
and Horner’s syndrome. 160 Brainstem involvement may result in treated with SRS or SRT is reported as 745 days 167 and 441
other regional cranial nerve deficits and long tract signs depending days. 171 RT may be superior to palliative and surgical treatment,
on size and invasiveness of the mass (see Fig. 31.7D). Peripheral particularly with respect to resolving neurologic signs in cases with
nerve lymphoma may present with a clinical history similar to clinical and imaging evidence of brainstem involvement. 111,167,171
PNST or with neurolymphomatosis. In the latter scenario, flac- Peripheral nerve lymphomas, which may be indistinguishable
cid tetraparesis and hyporeflexia can reflect the diffuse neoplastic from PNST, may respond to radiation or chemotherapy, although
inflitrative neuropathy. 161 no current literature provides specific treatment recommendations
or outcomes of dogs or cats with peripheral nerve lymphoma or
Diagnosis of PNSTs neurolymphomatosis.
Approximately 33% of cases with PNST affecting the brachial References
plexus will have a palpable mass on physical examination. 157,163,165
Ultrasound of the axillary region appears to be more sensitive for 1. Song RB, Vite CH, Bradley CE, et al.: Postmortem evaluation of
the detection of mass lesions than palpation, but not as useful as 435 cases of intracranial neoplasia in dogs and relationship of neo-
MRI. 166 plasm with breed, age, and body weight, J Vet Intern Med 27:1143–
PNST can be challenging to diagnose, and exploratory 1152, 2013.
surgery and biopsy is sometimes required. The most useful 2. Snyder JM, Shofer FS, Van Winkle TJ, et al.: Primary intracra-
imaging tool for diagnosing PNST and discriminating other nial neoplasia in dogs: 173 cases (1986–2003), J Vet Intern Med
etiologies of the observed clinical signs is MRI, whether the 20:669–675, 2006.
lesion involves a plexus, the SC, or a cranial nerve, although 3. Troxel MT, Vite CH, Van Winkle TJ, et al.: Feline intracranial neo-
CT-myelography is described. 160,166 To facilitate the diagno- plasia: retrospective review of 160 cases (1985–2001), J Vet Intern
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in part on tumor location and whether or not the tumor is ame- 9. Rossmeisl JH: New treatment modalities for brain tumors in dogs
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canal, which occurs in 45% of dogs, and the presence of tumor processes in mammalian glioma, Sci Rep 8:1180, 2018.
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DC, 1999, Armed Forces Institute of Pathology.
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