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.