Shortly after admission the dog began seizure-like activity and went in to respiratory arrest and was subsequently euthanized. The animal had 3.0 x 4.0 cm white-tan, granular focus on the lateral aspect of the temporal lobe of the left cerebral hemisphere. This area and the meninges were adhered to the parietal and temporal bones. On cross-section, the mass compressed and invaded the cerebrum. The meninges are focally expanded by sheets of neoplastic cells which focally compress and invade the cerebrum.
Neoplastic cells are multifocally necrotic.
Plasma cells and lymphocytes infiltrate the neoplasm in multiple foci and extend into the surrounding meninges. The intracytoplasmic granules stain strongly positive with a periodic acid-Schiff reaction. The granular cell tumor is a rare and generally benign neoplasm that has been reported in various species including humans, dogs, horses, rats, cats and a cockatiel. In animals, granular cell tumors are most common in the dog, horse and rat. In the dog, meninges and cerebrum are atypical locations for the granular cell tumor.