Page 690 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

668 PART IV Specific Malignancies in the Small Animal Patient

intracranial tumors, the commonly encountered vertebral and SC Treatment and Prognosis for Tumors Affecting
tumors often display characteristic MRI features that allow for pre- the Spinal Cord
sumptive diagnosis, but definitive diagnosis can only be obtained
VetBooks.ir with histopathology, as there exists considerable overlap in the MRI There is limited information on the results of treatment of ver-
tebral or SC tumors in veterinary medicine; however, treatment
features of specific tumor types with other neoplasms and non-
neoplastic lesions. 130,131,135,146,147 Meningiomas usually appear options parallel those available for brain tumor management. The
as focal ID-EM masses, often strongly enhancing on postcontrast principles and outcomes associated with palliative treatment of
MRI sequences, and frequently demonstrate a dural tail (see Figs. SC tumors are also generally similar those of brain tumors, with
31.6A, B). 131 Although spinal lymphoma is commonly described as the major exception of the more intensive and multimodal pain
an extradural mass lesion, especially in cats, it is very often a mixed and urinary bladder management plans that are often required in
compartment neoplasm in dogs and involves extraneural tissues in animals with SC tumors. Palliative treatment of vertebral and SC
both species. 77,136–139 Plasma cell tumors and lymphoma both cause tumors rarely results in prolonged STs or satisfactory functional
osteolysis, though the latter typically spares the cortex. 148 Short tau outcomes, with MST ranging from 0 to 105 days. 128,129,134,135
inversion recovery (STIR) MR sequences have been reported to In general, despite the type of treatments currently administered,
have the most utility for the detection of vertebral (see Figs. 31.5D, many dogs and cats with vertebral and SC tumors die or are euth-
31.6A) or SC tumors involving multiple compartments. 148 anized because of tumor-related causes, which often present as a
recurrence or progression of neurologic signs. 126,128,130,131 Thus
Tumor Biopsy and Pathologys presumed and confirmed local treatment failures remain a signifi-
Biopsy of tumors affecting the vertebrae or SC is required for cant source of morbidity and mortality in animals with vertebral
definitive diagnosis. Biopsy is often achieved at the time of surgi- and SC tumors (see Figs. 31.6A–C).
cal excision, but needle biopsy can be performed using percutane-
ous, surgical free-hand and image-guided techniques, including Chemotherapy
ultrasonography and CT (see Fig. 31.5H). 149 Chemotherapy may be used as an effective primary treatment
Among ED tumors arising from the vertebra, OSA is the modality in cases of vertebral plasma cell tumors, multiple
most common followed by CSA and FSA. 125,130,133 A variety myeloma, or lymphoma. 132,138,140 Dogs with vertebral plasma-
of ED (often epidural) tumors that often do not involve the cytomas and multiple myeloma may have favorable and durable
vertebra but arise from adipose tissue have also been reported, responses to melphalan and prednisone chemotherapy, even in the
including lipomas, infiltrative lipomas, liposarcomas, and face of multiple or diffuse vertebral lesions and signs of moderate
myelolipomas. Solitary plasma cell tumors affecting the ver- SC dysfunction. 132 Although there exist numerous reports on SC
tebra are classified as plasmacytomas (see Figs. 31.5A, B) and lymphoma in dogs in cats, there is limited information on spe-
may precede multiple myeloma. 132 Meningiomas and nerve cific chemotherapy protocols used and the results of treatment,
sheath tumors are the two most common ID-EM neoplasms, specifically with respect to survival and neurologic functional end-
with meningiomas predominating. Nephroblastomas also are points .138,140 Six cats with lymphoma treated with a combination
predominantly ID-EM tumors, and almost always are found of vincristine, cyclophosphamide, and prednisone had a complete
between T9 and L2 spinal cord segments because of the embry- remission rate of 50% and the median duration of remission was
ologic origin of the metanephric blastema from which they 14 weeks. 150 Platinum-based chemotherapeutic agents are often
arise. 142,143 Approximately 80% of canine nephroblastomas use as adjunctive treatment in cases of vertebral OSA. 129
will demonstrate immunoreactivity to WT-1, a human nephro-
blastoma gene product. 142 Surgery and Radiation Therapy
When lymphoma involves the neuraxis in dogs and cats, it is In addition to providing a histopathologic diagnosis, cytoreduc-
most often a manifestation of multicentric disease. 136,138,139 In tive surgery often results in a significant acute clinical benefit from
cats with SC lymphoma, more than 80% had extraneural organ SC decompression. 128,129,131,133 Depending on the tumor type,
involvement that commonly included the bone marrow, kid- surgery alone may convey sustained improvement in neurologic
neys, liver, spleen, lymph nodes, and 43% had concurrent brain function.
involvement. 138 Immunophenotypic characterizations of the Meningiomas can be treated effectively with surgery, with or
vast majority of canine and feline cases of nervous system lym- without postoperative RT. 131,133 The MSTs for dogs with intraspi-
phomas have not been performed, but both B- and T-cell lym- nal meningioma treated with surgery alone vary widely and range
phomas have been reported. 136,139 In a recent report of canine from 6 to 47 months. 129,131,151,152 Serious surgical adverse events
lymphoma, the only case of primary CNS lymphoma identified are more common with treatment of cranial cervical meningiomas
in the patient cohort was restricted to the SC, and was a dif- because of compromise of critical respiratory or vascular struc-
fuse large B-cell lymphoma characterized by CD79a staining. 136 tures. 131 The addition of postoperative RT in dogs with menin-
Among the 36 cases of metastatic canine CNS lymphomas in giomas increased the MST to approximately 45 months; dogs
this series, 55% were B-cell lymphomas and 45% were of T-cell receiving RT took significantly longer to neurologically decline
lineage. 136 than dogs that did not, thus delaying the period to clinical dete-
rioration because of local treatment failure. 131 In cats with spi-
Cerebrospinal Fluid Analysis nal meningiomas treated surgically, reported MSTs are 6 to 17
CSF analysis is frequently done in combination with cross-sec- months. 133,144
tional imaging and is a sensitive but nonspecific test that does not Vertebral tumors in dogs and cats are frequently treated with
usually provide a diagnosis, with the exception of lymphoma. In multimodal therapy consisting of surgery, RT, and/or chemo-
68% of dogs with CNS lymphoma in one series, a diagnosis was therapy. The long-term prognosis associated with vertebral
made using CSF analysis, and a diagnostic CSF was more likely tumors is guarded, with one study reporting an overall MST of
when infiltrative meningeal lesions were seen on MRI. 136 4.5 months in dogs with a variety of vertebral tumors. 129 In this