Ganglioneuroma in the Adrenal Gland of a Rat.

Necropsy was performed on a 22-month-old male Fischer 344 rat (Rattus norvegicus) that had weight loss and was icteric. Examination revealed a large, smooth, circumscribed, tan mass located at the cranial border of the right kidney. Microscopically, the mass consisted almost entirely of well-differentiated ganglion cells mixed with satellite and Schwann cells within a neurofibrillar matrix.