Cutaneous meningothelial proliferative lesions of the parietal skin in eleven cats.

Meningothelial proliferative diseases can rarely occur in extracranial sites, but there is limited information about them in veterinary medicine. This study investigated cutaneous meningothelial proliferative disease in eleven cats. Five cases were microscopically diagnosed with cutaneous meningioma and six cases with meningothelial hamartoma. Three of the former cases were subclassified as fibrous type and two as meningothelial type. The proliferating cells were positive for vimentin and E-cadherin, partially positive for cytokeratin, and negative for S100. All the lesions were located in the midline of the parietal skin and occurred at a young age. These facts suggest that both diseases in cats may be a congenital disease caused by ectopic meningothelial remnants during the fetal period.