Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Gardner syndrome is known as a variant of familial adenomatous polyposis. The term "Gardner syndrome" is used to describe extracolonic manifestations, such as osteomas, skin cysts, congenital hypertrophy of the retinal pigment epithelium, and desmoid tumors. Osteomas are benign, slow-growing lesions consisting of well-differentiated mature bone. The presence of multiple osteomas, particularly in the sinuses and the mandible, should strongly suggest the possibility of Gardner syndrome (A–D, arrows). In addition, dental abnormalities such as supernumerary, absent, or unerupted teeth and odontomas can be seen. A colonoscopy should be suggested.