Papillary meningioma in the dog: a clinicopathological study of two cases

Two cases of canine papillary meningioma are reported. The first animal, an 11-year-old male Boxer, presented with vestibular ataxia and the tumour was located in the left pontomedullary region. The second animal, a 15-year-old female cross-bred Miniature Poodle, presented with dementia, truncal ataxia and hypermetria, and the tumour was located in the right semilunar ganglion of Gasser. In the first case, histopathological examination showed that the papillary pattern merged with a typical syncytial meningioma, with extensive areas of necrosis. In the second case, the multilobular tumour had lobules with a purely syncytial, fibrous or transitional histological pattern, and lobules with intermingling papillary and secretory histological patterns. Both tumours exhibited histological features of malignancy, but evidence of remote metastasis was not found.