A benign epithelial tumor growing exophytically (outwardly projecting) in nipple-like and often finger-like fronds. In this context, papilla refers to the projection created by the tumor, not a tumor on an already existing papilla (such as the nipple).

When used without context, it frequently refers to infections (squamous cell papilloma) caused by human papillomavirus (HPV), such as warts. Human papillomavirus infection is a cause of cervical cancer, vulvar cancer, vaginal cancer, penis cancer, anal cancer, and HPV-positive oropharyngeal cancers. Most viral warts are caused by HPV infection, of which there are nearly 200 distinct human papillomaviruses, and many HPV types are carcinogenic.