A neurotropic lymphoma in the brachial plexus of a cat

Neuropathology of Central and Peripheral Nervous System Lymphoma in Dogs and Cats: A Study of 92 Cases and Review of the Literature

The literature about nervous system lymphoma (NSL) in dogs and cats is fragmentary, based on a few case series and case reports with heterogeneous results. The aim of our study was to retrospectively analyze 45 cases of canine and 47 cases of feline NSL and compare our results with previously reported data, also providing an extensive literature review. Breed, age, gender, clinical signs, type, and neurolocalization were recorded for each case. The pathological patterns and phenotype were assessed by histopathology and immunohistochemistry. The occurrence of central and peripheral NSL was similar between the two species in both primary and secondary types. NSL occurred with a slightly higher prevalence in Labrador Retrievers, and spinal cord lymphoma (SCL) was associated with young age in cats. The most frequent locations were the forebrain in dogs and the thoracolumbar segment in cats. Primary central nervous system lymphoma (CNSL) in cats most frequently involved the forebrain meninges, particularly as a B-cell phenotype. Peripheral NSL mostly affected the sciatic nerve in dogs and had no preferred location in cats. Nine different pathological patterns were identified, with extradural as the most prevalent SCL pattern in both species. Finally, lymphomatosis cerebri was described for the first time in a dog.

Feline lymphoma of the nervous system. Immunophenotype and anatomical patterns in 24 cases

This study aimed to describe the specific localization and anatomical pattern of 24 feline lymphomas of the nervous system for which the immunophenotype was identified by immunohistochemistry investigations to support the potential specific correlation between subtypes and anatomical patterns. In total 10 tumors affected the spinal cord, eight the brain, four the peripheral nerves, one involved both the brain and the spinal cord, and one simultaneously the brain and the optic nerves. Twenty two tumors were primary lymphomas. The affected animals were 8 years of mean age. Tumors developed as an extra-axial mass (11 cases), intra-axial mass (six cases), leptomeningeal lymphomatosis (three cases), and neurolymphomatosis (five cases). One of them expressed both leptomeningeal lymphomatosis and neurolymphomatosis patterns. Two intra-axial brain lymphomas showed an angiotropic pattern. The optic chiasm was the most involved site for neurolymphomatosis. Immunolabeling was performed using anti-CD3, CD20, CD79a, PAX5, MUM-1, CD56, and anti-CD44 antibodies. In total, 12 tumors consisted of B cell lymphomas, and six of T cell lymphomas, two cases were double-reactive lymphomas while two cases consisted of non-B non-T lymphomas. B cell lymphoma affected animals of 6.4 years of mean age, while the T cell lymphoma affected older animals (mean age of 11.1 years). Extra-axial tumors mainly consisted of B cell lymphomas (8/11). Neurolymphomatosis expressed different immunophenotypes, and the B cell phenotype was the most prevalent in the optic chiasm. Two leptomeningeal lymphomatoses expressed T cell immunophenotype. For the first time, plasmacytoid differentiation was found for angiotropic lymphoma and neurolymphomatosis. All the cases, except one, were CD56-negative. CD44-expression confirmed a common malignant potential for all the anatomical patterns of the nervous system lymphoma in cats. Immunophenotype of feline lymphoma of the nervous system and its potential association with specific anatomical patterns should be strongly required in the diagnostic workup and clinical approach to this tumor especially when its primary origin is confirmed.

Primary nervous system lymphoma in cats

Here we characterize the neuroanatomic distribution, neuropathology, and immunophenotype of 10 cases of primary nervous system lymphoma in cats. Cases were retrospectively searched from 2 academic institutions. Selected cases were reviewed and subjected to immunohistochemistry (IHC) for CD3, CD20, and Pax5. The mean age of affected cats was 9.1 y, and no sex or breed predilection was observed. The most common clinical sign was ataxia (8 cases). Gross changes reported in 8 cases consisted of white-to-tan masses (7 cases) or swelling (1 case) within the neuroparenchyma (5 cases) or epidural spaces (3 cases). Histologically, intraparenchymal lymphomas occurred in the gray and white matter or perivascular spaces (7 cases); extraparenchymal lymphomas (6 cases) consisted of neoplastic cell infiltration of the perivascular spaces in the leptomeninges, choroid plexus, or epidural spaces. Nerve lymphomas were diffusely infiltrative. Tumors occurred in the brain (4 cases), spinal cord and nerves (3 cases), spinal cord (2 cases), and brain, spinal cord, and nerves (1 case). IHC was consistent with a B-cell lymphoma in 5 cases and with a T-cell lymphoma in 5 cases.

Clinical and magnetic resonance imaging features of lymphoma involving the nervous system in cats

Background

Lymphoma is the most common spinal cord neoplasm and second most common intracranial tumor in cats, but description of specific magnetic resonance imaging (MRI) features is lacking.

Objective

Describe the clinical and MRI features of lymphoma affecting the central (CNS) or peripheral (PNS) nervous system or both in cats.

Animals

Thirty‐one cats with confirmed cytological or histopathological diagnosis or both of lymphoma involving the CNS or PNS or both, and MRI findings of the lesions.

Methods

Multicenter retrospective descriptive study. Signalment and medical information were recorded. Magnetic resonance imaging findings were reviewed by 3 observers following a list of predefined criteria and consensus was sought. Frequency distributions of the different categorical data were reported.

Results

Median duration of clinical signs at time of presentation was 14 days (range, 1‐90). Neurological examination was abnormal in 30/31 cats. On MRI, lesions affecting the CNS were diagnosed in 18/31 cats, lesions in both CNS and PNS in 12/31, and lesions in the PNS only in 1/31. Intracranial lesions were diagnosed in 22 cats (extra‐axial, 7/22; intra‐axial, 2/22; mixed, 13/22), and spinal lesions were diagnosed in 12 (6/12 involving the conus medullaris and lumbosacral plexuses). Infiltration of adjacent extra‐neural tissue was present in 11/31 cases. Contrast enhancement was seen in all lesions, being marked in 25/30. Meningeal enhancement was present in all but 2 cases. Several distinct MRI patterns were observed.

Conclusions and Clinical Importance

Nervous system lymphoma in cats has a wide range of MRI features, of which none is pathognomonic. However, together with clinical data and cerebrospinal fluid (CSF) analysis, MRI may provide a strong tentative antemortem diagnosis.

Imaging and histopathologic features of reversible nerve root and peripheral nerve edema secondary to disc herniation in a cat

Nerve root enlargement with increased contrast uptake has been reported in dogs and humans secondary to nerve root compression. In cats, nerve root enlargement and contrast uptake only have been reported in association with inflammatory and neoplastic diseases, but not as a sequela to nerve root compression. An 8‐year‐old oriental short hair cat was presented with acute neurologic deficits consistent with left‐sided sciatic nerve deficit and possible L6‐S1 myelopathy. Magnetic resonance imaging (MRI) was performed and identified compression of the cauda equina and L7 nerve root associated with intervertebral disc herniation (IVDH) at L6‐L7 as well as widespread sciatic nerve enlargement with moderate rim enhancement. A hemilaminectomy was performed to evacuate herniated disc material. The nerve root was biopsied and submitted for histological evaluation. Interstitial nerve edema was diagnosed. Follow‐up MRI 3 months postoperatively showed complete remission of the changes. Nerve root thickening together with contrast enhancement may represent nerve edema in cats secondary to IVDH.

Feline lymphoma in the nervous system: pathological, immunohistochemical, and etiological aspects in 16 cats

ABSTRACT: The pathological, immunohistochemical (IHC), and etiological features of lymphoma involving the nervous system (NS) in cats were analyzed through a retrospective study (2004-2017) in Rio Grande do Sul State, Brazil. The NS involvement was observed in 16 (12.2%) of 125 felines with lymphoma. Young cats were mainly affected, with a median of 24 months old. Most cases were secondary central NS lymphoma, whereas in three cats, the NS involvement was primary. IHC revealed 14 (87.5%) FeLV-positive, six FIV-positive, and one FeLV/FIV-negative cats. Distribution of feline lymphoma in the NS was 8/16 in the spinal cord, 7/16 in the brain, and 1/16 in the paravertebral nerves and ganglia (neurolymphomatosis). The lymphoma pattern in the spinal cord was exclusively extradural, often focal (6/8), and located in the lumbar (3/6), sacral (1/6), thoracic (1/6), and cervical segments (1/6). Brain neuroanatomical patterns were: leptomeningeal lymphomatosis (4/7), lymphomatous choroiditis (2/7), and intradural lymphoma (1/7). The feline with primary neurolymphomatosis presented a marked thickening of paravertebral nerves and ganglia from the sacral region. B-cell lymphoma (75%) was often diagnosed, and diffuse large B-cell lymphoma (DLBCL) (11/16) was the main subtype. T-cell lymphoma (25%) was less commonly observed and was classified as peripheral T-cell lymphoma (PTCL) (3/16) and T-cell lymphoblastic lymphoma (T-LBL) (1/16).

CD56+ B-cell Neurolymphomatosis in a Cat

A 16-year-old male Russian blue cat was presented with acute onset of paraparesis of the forelimbs that progressed to tetraparesis. Neurological examination revealed non-ambulatory tetraparesis with decreased postural reactions in all four limbs. Magnetic resonance imaging revealed multifocal nerve root swelling on the right at C6/C7 and C7/T1, while ultrasonography demonstrated swelling of the right brachial plexus. To understand the cause of the nerve swelling, the right musculocutaneous nerve arising from the brachial plexus and the pectoralis muscle were biopsied. Histologically, there was evidence of neurolymphomatosis (neurotropic lymphoma) with Wallerian degeneration and denervation atrophy of myofibres. The neoplastic lymphoid cells expressed CD79a, CD20 and CD56. Based on these findings, a diagnosis of B-cell neurolymphomatosis was made. Expression of CD56, synonymous with neural cell adhesion molecule, is rare in B-cell lymphomas and has not been reported in feline B-cell lymphomas or feline neurolymphomatosis. CD56 expression was suspected to have played an important role in neurotropism of the neoplastic cells in this case.

Neurolymphomatosis caused by T-cell lymphosarcoma in a cat: imaging description and treatment review

CASE SUMMARY

A 16-year-old domestic shorthair cat was evaluated for acute-onset right pelvic limb monoparesis localized to the sciatic nerve. MRI revealed a homogeneously contrast-enhancing, well-demarcated mass effacing the right sciatic nerve from its intravertebral origin to the end of the viewable field (mid-femur). Abdominal ultrasound revealed thickened small intestinal loops and enlarged mesenteric lymph nodes. Cytology of the small intestine was suggestive of lymphosarcoma. T-cell lymphosarcoma of the sciatic nerve and small intestines was confirmed with incisional biopsy. Treatment consisted of systemic chemotherapy with vincristine followed by the Wisconsin-Madison feline lymphosarcoma protocol, but despite treatment the patient neurologically worsened and was euthanized after 54 days.

RELEVANCE AND NOVEL INFORMATION

We present herein one of the first descriptions of neurolymphomatosis in the domestic cat that included post-intravenous contrast MRI. Treatment options based on recommendations for people with neurolymphomatosis include systemic chemotherapy, intrathecal chemotherapy and/or localized radiation chemotherapy. The authors recommend that all cats be screened for concurrent non-neuronal areas of lymphosarcoma before undergoing treatment for neurolymphomatosis, regardless of clinical signs.

Distribution of feline lymphoma in the central and peripheral nervous systems

In cats, lymphoma (lymphosarcoma) is the most common neoplasm affecting the spinal cord and the second most common intracranial tumour. Although lymphoma commonly develops in the spinal cord as a part of a multicentric process, a primary form may occur. Lymphoma can exhibit a wide range of morphological patterns, including intraparenchymal brain mass, lymphomatosis cerebri, intravascular lymphoma, lymphomatous choroiditis and meningitis, extradural, intradural-extramedullary or intramedullary lymphoma in the spinal cord, or neurolymphomatosis in the peripheral nerves. Lymphoma may occur as a paraneoplastic disorder associated with peripheral neuropathies. Magnetic resonance imaging (MRI) and computed tomography (CT) are the techniques of choice for morphological assessment of nervous system lesions in vivo. However, biopsy should be performed to achieve a definitive diagnosis. Knowledge of the different morphological patterns expressed by lymphoma in the nervous system of cats allows veterinary clinicians to suspect lymphoma and to arrange appropriate diagnostic procedures, including immunophenotype and clonality studies, along with therapeutic protocols and prognostic evaluations.

Neurolymphomatosis in a cat

A 9-year-old male mixed breed cat showed chronic progressive neurological symptoms, which are represented by ataxia and seizures. At necropsy, spinal roots and spinal ganglions at the level of sixth cervical nerve to second thoracic nerve were bilaterally swollen and replaced by white mass lesions. Right brachial plexus and cranial nerves (III, V and VII) were also swollen. A mass lesion was found in the right frontal lobe of the cerebrum. Histologically, neoplastic lymphocytes extensively involved the peripheral nerves, and they infiltrated into the cerebral and spinal parenchyma according to the peripheral nerve tract. Immunohistochemically, most neoplastic lymphocytes were positive for CD20. The clinical and histological features in this case resemble those of neurolymphomatosis in humans.

Extranodal lymphoma with peripheral nervous system involvement in a dog

An 8-year-old neutered female Cavalier King Charles spaniel was evaluated for progressing right forelimb lameness. Magnetic resonance imaging revealed that the right-side radial nerves and the caudal brachial plexus were swollen. The histological and molecular biological diagnosis by partial biopsy of the C8 spinal nerve was T-cell lymphoma. Coadministration of lomustine and irradiation was started. However, this therapy was ineffective. At necropsy, neoplastic tissues were seen extending into the subarachnoid space of the spinal cord, liver, pancreas and kidneys as gross findings. A large mass was also identified occupying the caudal thorax. Histologic findings included infiltration in these organs and the mass by neoplastic lymphocytes. To date, involvement of peripheral nerves (neurolymphomatosis) is rarely reported in veterinary species.

Ultrasonographic study of the feline sciatic nerve

This study was conducted to describe the ultrasonographic appearance and technique for the evaluation of sciatic nerve (ScN) in cats. An anatomical study was carried out using six feline cadavers to determine anatomic landmarks. An ultrasonographic 'in vitro' study was performed using eight pelvic limbs from four fresh feline cadavers to assess the ScN in three regions (glutea, femoralis and popliteal) using a 4-13MHz linear transducer. Five healthy adult experimental cats were employed for an 'in vivo' ultrasonographic study of the ScN using the same protocol described for the 'in vitro' study. The ultrasonographic images of the ScN were well correlated with those obtained in the anatomical study. The ScN was easily identified in all the approaches. The ScN was observed as a hypoechoic structure with internal echoes, outlined by hyperechoic lines. This study shows the usefulness of ultrasound to evaluate the entire pathology of the ScN in the cat.