Page 749 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 33 Hematopoietic Tumors 727

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A B
• Fig. 33.17 (A) Ventrodorsal projection of a cat with real lymphoma. Massive bilateral renomegaly is
observed. (B) Necropsy specimen of a cat with bilateral renal lymphoma illustrating the diffuse cortical
nature of the disease that is most common.

the most common malignancies encoutered in the CNS in cats. 579 In cats with suspected spinal lymphoma, survey radiographs of
Although some discordance exists in the literature, cats with CNS the spine will rarely reveal osseous lesions. CT or MRI are preferred
lymphoma are younger (median age, 4.0–10.5 years) and 17% 580 and, in approximately 75% of the cases, an extradural or intradu-
to 50% of cases are FeLV antigenemic. 577,578,581 As most reports ral mass will be detected. 577,579,580,582–584 Most lesions occur at a
are older, these data may no longer hold true in the current era. thoracolumbar or lumbosacral location and are often multifocal.
Approximately two-thirds of intracranial cases also have multi- Image-guided FNA of epidural lesions may yield a cytologic diag-
centric and extracranial disease; and approximately 40% of spinal nosis. CT or MRI also reveals multifocal disease in the majority
lymphoma cases occur in multiple spinal cord sites with one-third of cats with intracranial lymphoma. 577,580 CSF analysis may be
also involving intracranial locations. 559,577–579,581 In a compila- helpful and could provide a definitive diagnosis in some cases.
tion of 160 cases of intracranial tumors in cats, diffuse cerebral One of 11 cats with confirmed spinal lymphoma in one study 578
and brainstem involvement was most common for lymphoid and six of 17 with confirmed intracranial lymphoma in another
malignancies. 577 Spinal lesions are usually both extradural and study 577 had evidence of neoplastic lymphocytes in the CNS, and
intradural, although they can be limited to one or the other com- an increased protein content was commonly found. Bone marrow
partment. 578 Feline CNS lymphoma may be primary, but more and renal involvement are often present, and cytologic assessment
commonly (approximately 80%) represents a multicentric process of these or other more accessible involved organs is generally more
(especially with renal or bone marrow involvement). 577,581–583 A easily attainable than from spinal sites.
paucity of information exists on the immunophenotype of CNS Few cases report chemotherapy treatment and outcome for
lymphoma. CNS lymphoma, and although an occasional case has experi-
Cats with CNS lymphoma can present with constitutional enced durable response to systemic chemotherapy, generally fewer
signs (hyporexia, lethargy) and signs referring to intracranial than 50% will respond and MSTs of 1 to 4 months can be expec
lesions, spinal lesions, or both. 577–580,582,583 Intracranial signs may ted. 528,559,572,577,578 RT may be used and generally brisk responses
include ataxia, altered consciousness, aggression, central blind- would be expected owing to the inherent radiosensitivity of lym-
ness, and vestibular abnormalities. In a study of cats with seizures, phocytes. Adjuvant chemotherapy should be considered, as many
of those diagnosed with intracranial lesions, 8% were due to lym- cases with CNS lymphoma have documented bone marrow or
phoma. 580 Clinical signs referring to spinal cord involvement may renal involvement. 582,583
include paresis or paraplegia (>80% with tetraparesis in 20%),
ataxia, pain, constipation, and nonspecific constitutional signs Cutaneous Lymphoma
(e.g., hyporexia, lethargy, weight loss). 578,582 Neurologic examina-
tion may further reveal lower or upper motor neuron bladder, tail Cutaneous lymphoma is a rarely encountered anatomic form in
flaccidity, and absent deep pain; approximately one-third of cats the cat. It is usually seen in older cats (median age, 10.0–13.5
will be asymmetric and most refer to thoracolumbar involvement. years) with no sex or breed predominance, and is not associated
The neurologic dysfunction may be insidious or progress rapidly. with FeLV/FIV. 585,586 Cutaneous lymphoma may be solitary or