A Comparison of the Cytologic and Histologic Features of Meningiomas in Four Dogs

The cytologic and histologic features of 2 intracranial and 2 spinal (extramedullary cervical) canine meningiomas were compared. Cerebrospinal fluid analysis in 2 cases revealed mild, mixed cell pleocytosis, primarily composed of small lymphocytes and monocytoid cells, with a moderate increase in total protein concentration. Cytologic features suggestive of meningioma included cells with both epithelial and mesenchymal characteristics and a tendency towards cell clustering. Tumor location also was useful in making a diagnosis. The 4 meningiomas differed histologically from one another, and included angioblastic, psammomatous, meningotheliomatous, and microcystic anaplastic types, which conformed to a classification scheme for human meningiomas. The classification scheme could not be applied to cytologic specimens.