Imaging of orbitofrontal cholesterol granuloma.

The radiological findings in 31 patients with a histologically proven orbitofrontal cholesterol granuloma are presented. Plain films and computed tomography (CT) both show a characteristic lytic lesion allowing a reasonably confident diagnosis to be made preoperatively, thus facilitating appropriate surgery. The most important differential diagnoses on clinico-radiological grounds are lacrimal gland carcinoma and dermoid cyst. On plain films cholesterol granulomas typically show constancy of site, lysis of the superior orbital margin, frequent extension into the frontozygomatic process and absent or minimal surrounding sclerosis. On CT ragged bone destruction with a soft tissue mass no denser than brain extending extraperiosteally into the orbit are the most typical features. MRI and other imaging modalities are discussed.