Keratoameloblastoma fall into four groups: 1) papilliferous
histology 2) simple histology 3) simple histology with odontogenic keratocyst (OKC)like features (4) complex histology.
The papilliferous surface is considered to result from exposure to the hemodynamic stress of flowing blood.
The differential diagnosis of PFE includes other papilliferous lesions of the heart, such as myxomas, Lambl excrescences, bacterial vegetations, and organizing marantic (thrombotic) endocarditis.
Not every sebaceous nevus advances to the third stage, which is characterized by the transformation of skin appendages into secondary neoplasms--namely, papilliferous syringadenomas and basal cell carcinomas.
3, 4) Jones and Heyl studied 140 cases of sebaceous nevi and found that nearly 20% transformed into papilliferous syringadenomas.