Immunohistochemical investigation on canine meningiomas

Immunohistochemical staining patterns were studied in brain and spinal cord meningiomas of the dog. Nineteen archived cases were selected and classified according WHO classification (Koestner et al. 1999). They included five transitional, five meningothelial, two fibroblastic, two angiomatous and five anaplastic meningiomas. To differentiate meningioma from other central nervous system tumors a panel of immunohistochemical markers (vimentin, S100, Glial Fibrillary Acidic Protein (GFAP), Pancytokeratin, AE1/AE3 cytokeratin) were checked. Moreover, E-cadherin and beta-catenin expressions were investigated in order to identify the role they eventually play in meningioma’s morphogenesis. In all cases, vimentin labelling was strong and was detected in 100% of neoplastic cells. S100 expression was detected in 2 out of 19 cases (meningothelial and anaplastic type), showing to be mild and focal. GFAP, Pancytokeratin and AE1/AE3 cytokeratin were negative in all cases under study. E-cadherin was expressed in 3 out of 19 cases as focal, granular, cytoplasmic/membranous positivity. Whorl figures were E-cadherin positive in one transitional meningioma, one meningothelial and one anaplastic hystotypes, while neoplastic cells were negative in both the fibroblastic and angiomatous morphotype. Beta-catenin was not expressed. E-cadherin expression reflected the presence of homotypic interactions of neoplastic cells in the meningothelial as well as transitional hystotypes.