History: Dog, Staffordshire terrier, 4 years.
Diagnosis: Brain, cerebellum, fourth ventricle, brain stem / medulla: epidermoid cyst with severe compression atrophy of cerebellum and brain stem / medulla
Description: Macroscopically, a white, 1.5 cm in diameter almost median mass extended the fourth ventricle between cerebellum and brain stem / medulla). It was encapsulated and had a crumbly cut surface. In addition, moderate hydrocephaly of the lateral ventricles was observed due to obstruction of the fourth ventricle. Histologically, the cyst was lined by multilayered stratified squamous epithelium and contained abundant keratin.
Comments: Of note, the dog had no neurological symptoms the epidermoid cyst therefore apparently represented an incidental finding.
Picture by Anja Meyer, Department of Veterinary Pathology, Freie Universität Berlin, Germany
Author: Patricia Klose, Department of Veterinary Pathology, Freie Universität Berlin, Germany