Transitional Meningioma in a Golden Retriever Dog - A Case Report

Meningiomas are the common central nervous system tumors seen in dogs. There are nine histological subtypes of meningioma are reported so far. A 7-year-old male golden retriever dog presented to Small Animal Medicine and Surgery Unit with a history of progressive paralysis of all four limbs and enophthalmos of the left eye along with depressed left frontal region. Computerized Tomography scan of skull showed enlarged rostral alar foramen. Animal collapsed suddenly and brought for post mortem to Department of Veterinary Pathology, Madras Veterinary College, Chennai. Muscle atrophy noticed in left frontal area and examination of cranial cavity revealed a well encapsulated gray white mass noticed in the brain stem region. Cytological examination revealed the presence of epithelial and mesenchymal cells arranged in loose clusters as well as in pseudo palisading pattern in some areas. Cytological features were suggestive of meningioma. Histopathology revealed the presence of spindle shaped cells arranged in loose clusters and whirling pattern along with meningothelial cells arranged in fascicles which is suggestive of transitional type of meningioma. Positive histochemical staining with Masson trichome observed. For the confirmatory diagnosis immunohistochemical staining with cytokeratin, vimentin and epithelial membrane antigen was performed which is commonly used in human meningioma cases. Moderate cytoplasmic expression of cytokeratin and vimentin noticed in neoplastic cells. Immunohistochemical examination with epithelial membrane antigen showed moderate positive reaction by meningothelial as well as fibroblast cells. Based on the above findings the present case was diagnosed as transitional meningioma.