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Lymphoma, Central Nervous System 604.e3

Lymphoma, Central Nervous System Client Education
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VetBooks.ir Diseases and Disorders

liver, spleen, mesenteric lymph nodes,
BASIC INFORMATION
and cranial mediastinum. DIAGNOSIS
Definition ■ Most cats present with neurologic signs Diagnostic Overview
Lymphoma is a systemic malignant neoplasm at initial diagnosis, but some older The diagnosis is suspected based on signalment,
of lymphoid origin. Central nervous system studies have reported that up to 50% history, neurologic abnormalities, and MRI
(CNS) lymphoma can be primary, occurring of cats with renal lymphoma relapse imaging. Definitive diagnosis occasionally can
only within the CNS; or secondary, occurring with CNS involvement. be obtained from CSF analysis, but usually,
as part of multicentric disease. • CNS lymphoma can be categorized based a CNS lesion or, in patients with secondary
on anatomic site. CNS lymphoma, an extraneural lesion must
Synonyms ○ Intracranial disease affects the forebrain be sampled and evaluated cytologically or
Lymphosarcoma, malignant lymphoma, non- (cerebrum and diencephalon) more histologically.
Hodgkin’s lymphoma (human) often than the cerebellum and brain-
stem. Lesions can be focal, multifocal, Differential Diagnosis
Epidemiology or diffuse. Infiltration of the meninges • Intracranial lesions: other primary brain
SPECIES, AGE, SEX can occur with or without parenchymal tumors (meningioma, glioma, ependymoma,
In dogs, lymphoma is the most common involvement. choroid plexus tumor), toxoplasmosis, neo-
hematopoietic malignancy, but involvement ○ Involvement of cranial nerves III-VIII sporosis, meningoencephalitis of unknown
of the CNS is uncommon. There is no breed, has been reported (V and VII most origin (including granulomatous meningo-
age, or sex predisposition. commonly). encephalitis), ischemic encephalopathy, feline
• Lymphoma accounts for < 5% of all primary ○ Most lesions contain extradural and infectious peritonitis, fungal encephalitis
CNS tumors and < 10% of all CNS tumors intradural components, not only focal • Spinal lesions: intervertebral disc disease,
(primary and secondary) in dogs. extradural masses. Up to one-half of discospondylitis, abscess, fibrocartilaginous
In cats, lymphoma is the most common hema- affected cats have lesions involving emboli, infarction, spinal tumors (menin-
topoietic malignancy, and CNS involvement is multiple spinal cord sections. Concurrent gioma, glioma, nephroblastoma), vertebral
reported in 5%-10% of affected cats. brain and spinal involvement also can tumors (osteosarcoma, chondrosarcoma,
• Lymphoma accounts for about 15% of all occur. hemangiosarcoma, myeloma), feline infec-
brain tumors and 50% of all nonosseous ○ Brachial plexus involvement, possibly tious peritonitis
tumors affecting the spinal cord in cats. invading the spinal cord, can occur in • Peripheral nerve lesions: peripheral nerve
• There is no breed or sex predisposition. Cats dogs and cats. sheath tumor, trauma, avulsion of the bra-
of any age can be affected; those infected chial plexus or lumbosacral plexus, trigeminal
with feline leukemia virus (FeLV) tend to HISTORY, CHIEF COMPLAINT neuritis (dogs)
be < 5 years old. • Most patients present with acute and rapidly
progressive neurologic abnormalities. Initial Database
RISK FACTORS • Patients with secondary CNS lymphoma • Neurologic exam (p. 1136)
• FeLV increases the relative risk of lymphoma may have other signs referable to affected • CBC, serum chemistry panel, urinalysis
60-fold. More than 55% of cats with spinal extraneural sites. (pp. 602 and 603)
lymphoma are FeLV seropositive. Less than • FeLV/FIV serologic testing (cats)
20% of cats with brain involvement are FeLV PHYSICAL EXAM FINDINGS • Thoracic radiographs, abdominal ultrasound,
seropositive. • Forebrain lesions are associated with seizures, aspiration of enlarged lymph node or suspi-
• Feline immunodeficiency virus (FIV) increases mentation or behavioral changes, blindness, cious lesions identified on exam or imaging
the relative risk of lymphoma fivefold. conscious proprioceptive deficits with a study, bone marrow aspiration: screening for
normal gait, circling, and occasionally, neck evidence of lymphoma in other organ systems
Clinical Presentation pain. may allow a diagnosis to be reached rapidly
DISEASE FORMS/SUBTYPES • Brainstem lesions are associated with gait and less invasively.
• CNS lymphoma can be primary or secondary and proprioceptive abnormalities, vestibular
(see Definition above). changes, and occasionally, mentation changes Advanced or Confirmatory Testing
○ In dogs, CNS lymphoma is primary in (stupor or coma). • MRI is the imaging modality of choice for
20% of affected patients and secondary • Cranial nerve deficits: signs depend on the CNS lesions.
in 80%. specific nerve(s) affected. ○ Intracranial lesions can be intraaxial
Other common sites include lymph • Depending on segments involved, spinal cord or extraaxial. Spinal lesions can appear
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nodes, liver, spleen, and bone marrow. lesions can result in upper motor neuron extradural, intradural but extramedullary,
Up to one-half of dogs with secondary signs (stiff ataxic gait, proprioceptive deficits, or occasionally, intramedullary.
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CNS lymphoma do not have neurologic spastic paresis/paralysis, hyperreflexia) and/ ○ On T2-weighted images, lesions are hyper-
signs at initial diagnosis; neurologic or lower motor neuron signs (short-strided intense compared with white matter and
signs instead develop when the cancer gait, flaccid paresis/paralysis, hyporeflexia). hyperintense or isointense compared with
relapses. Back pain is rare. Signs can be bilateral but gray matter. Margins are often indistinct.
○ In cats, up to 30% of brain lymphomas usually are asymmetrical. ○ On T1-weighted images, lesions are
are primary, but only 15% of spinal • Brachial plexus tumors present with unilateral hypointense compared with white and
lymphomas are primary. sensory and motor deficits based on the gray matter. Contrast enhancement is
When CNS lymphoma is secondary, specific nerve roots affected. strong but often patchy.
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common sites affected concurrently ○ On fluid-attenuated inversion recovery
include the kidneys, bone marrow (with Etiology and Pathophysiology (FLAIR) images, lesions are hyperintense
or without circulating lymphoblasts), The cause is unknown. compared with white matter and isointense

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