Magnetic resonance imaging in the diagnosis of lymphoma involving the brachial plexus in a cat.

An 11-year-old, neutered, female Domestic Long Hair cat had a 3-week history of left forelimb lameness. Conscious proprioception and postural reflexes were absent on the left thoracic limb. The cat had slightly reduced placing and hopping responses on the left pelvic limb, absent cutaneous trunci muscle reflex on the left side, and left triceps muscle atrophy. Magnetic resonance imaging revealed a 2 x 2 x 2 cm mass in the region of the left brachial plexus. The cat was treated by left forelimb amputation and hemilaminectomy. Histopathology of the brachial plexus revealed lymphoma.