adnexal and skin appendage tumor squamous cell tumor inverted squamous papilloma A benign tumor consisting of villous or arborescent outgrowths of fibrovascular stroma covered by neoplastic epithelial cells in which proliferating epithelium is invaginated beneath the surface and is more smoothly rounded. (M-8053/0). MPATH:443 endophytic papilloma invaginated papilloma mouse_pathology.ontology papilloma