Extracranial meningioma in a dog

A case report

Abstract

A meningiothelial meningioma, forming a very large spherical mass about 15# cm in diameter, was found on the head in a 12-year-old female Pointer. Four years before the first clinical examination, a tumorlike mass about 1.0# cm in diameter had been noticed in the occipital subcutaneous tissue of the dog. In 4 years it grew in to a size of infant head.
On clinical examination, the tumor mass was so heavy that the dog could not keep the head in normal position. Radiography revealed that the mass was limited in the extracranial subcutaneous tissue and unrelated to the intracranial meninges. There were no distinct clinical signs. A biopsy specimen showed a typical pattern of meningothelial meningioma.
About 9 months after the successful excision of the tumor, the dog died of acute pneumonia. At necropsy, three grayish white spherical tumor masses 1.0-2.0#cm in diameter were found on the surface of the diaphragm of the lung and diagnosed histopathologically as metastatic nests of the primary meningioma. The origin of these tumors was unknown. It was speculated that the tumorigenesis might be related to the history of the dog, which had suffered from some small shots in the occipital region in the course of hunt-training at 2 years of age.