This tumor is thought to be derived from the parenchymal cells of the posterior lobe of the pituitary gland, called pituicytes. Some researchers believe that they arise from the folliculostellate cells in the anterior lobe of the pituitary. As such, it is a low-grade glioma.
A tumor thought to arise from the pituicyte cells in the posterior lobe of the pituitary gland may also originate from folliculostellate cells in the anterior lobe. Consequently, this tumor is classified as a low-grade glioma.