Single axial CT of the head without contrast shows a well defined, calcified mass within the left frontal sinus. This is the typical appearance for a Sinonasal Osteoma. Classically they are asymptomatic, and thus are incidental findings on imaging studies done for other reasons. Sinonasal osteomas are the most common benign tumor of the sinuses. They can be associated with Gardner syndrome, an autosomal dominant transmitted familial adenomatous polyposis syndrome.