An unexpected finding in the frontal sinus: cholesterol granuloma
In this case report we describe a lesion found in the frontal sinus of a 34-year-old man. CT showed an enlargement and opacification of the right frontal sinus. T2-weighted MR images demonstrated a mass lesion with a hyperintense centre and a surrounding hypointense rim. The T1-weighted images showed a hyperintense lesions as well, with a rim of intermediate intensity. The differential diagnosis included a mucocele, an ossifying fibroma, an osteoma and fibrous dysplasia. Based on pathological findings, the final diagnosis was a cholesterol granuloma. A cholesterol granuloma is known to be hyperintense on both T1 and T2-weighted images and to erode the surrounding bone. Cholesterol granuloma of the frontal sinus is a rare finding, usually this type of lesion is found in the temporal bone.