Primary intra-axial B-cell lymphoma in a cat.

A 3-year-old spayed, female, domestic shorthair cat presented in the recumbent position. Clinical examination revealed decreased consciousness and ataxia. Neurological findings suggested a lesion in the forebrain and brainstem, and magnetic resonance imaging (MRI) of the brain was performed. A nodular lesion approximately 1 cm in diameter in the left parietal lobe, overlying the temporal lobe, was observed on MRI scans. T2-weighted images revealed iso- to slightly low-intensity signals in the cerebral white matter. The lesion was detected as low-intensity signals by T1-weighted images and was emphasized by enhanced T1-weighted images. The cat died on the 3rd hospital day. By complete pathological examinations including immunohistochemical investigations, the cat was diagnosed as primary intra-axial B-cell lymphoma.