[Microcystic meningioma with pulmonary metastasis in canine: case report]

ABSTRACT Meningiomas are the main tumors of the central nervous system (CNS) affecting dogs and cats. In most of the cases they are benign neoplasms, usually expansive, causing compression of the CNS and rarely metastasize to other organs. We describe the occurrence of a microcystic meningioma with pulmonary metastasis in an 11 - year - old canine with clinical signs of staggering gait, head compression against objects, agitation, salivation and aggressiveness. At necropsy, well-defined, firm, granular-looking masses located in the parietal cortex and nuclei of the base were observed in the encephalon. Numerous micronodulations of similar appearance were observed in the lung. Histologically, nodules formed by spindle neoplastic cells with large, elongated nuclei and evident nuclei were loosely arranged, forming vacuoles and microcysts. Immunohistochemistry were strongly positive for cytokeratin and negative for vimentin. Through the histopathology and immunohistochemistry, it was possible to establish the histological classification of microcystic meningioma, as well as to differentiate from other diseases that present with nervous signals.