Choroid plexus papilloma
Choroid plexus tumors (papilloma or carcinoma) account for 10-20% of all intracranial neoplasms in the dog. These are epithelial neoplasms that arise from the normal choroid plexus and most commonly occur in the lateral ventricles or in the lateral aperture where the choroid plexus is abundant. The designation of papilloma vs. carcinoma is dependent on recognizing spread away from the primary tumor (if spread is noted then carcinoma is designated).
Choroid plexus tumors express a variery of cell adhesion molecules; however, these proteins are not specific to the choroid plexus. Recently, the inward potassium rectifier protein, Kir7.1, has been recognized as a specific immunohistochemical marker for choroid plexus tumors in the dog.
Choi EJ, Sloma EA, Miller AD. Kir7.1 immunoreactivity in canine choroid plexus tumors. J Vet Diag Invest 2016 28(4):464-468.
Reginato A, Girolami D, Menchetti L, Foiani G, Mandara MT. E-cadherin, N-cadherin expression and histologic characterization of canine choroid plexus tumors. Vet Pathol 2016 53(4):788-791.