Answer of October 2011

Clinical History:

50-year old male, presented with right sensorineural hearing loss. MRI was performed. (4 images: axial T1W x 2, axial T2W x 2)

Diagnosis:

Cholesterol Granuloma

Discussion:

Cholesterol granuloma is a benign lesion (1). It is characterized by a smooth marginated expansile lesion arising from petrous apex, with high signal in both T1W and T2W images. There is usually no internal enhancement (1-3). Signals of blood product or hemosiderin may be observed inside the lesion because of microhemorrhage. (1-3). 
Patients with cholesterol granuloma may present with symptoms and signs relating to the mass effect of the lesion on adjacent cranial nerves, such as sensorineural hearing loss, tennitis, hemifacial spasm, facial numbness, trigeminal neuralgia etc. The growth rate of cholesterol granuloma is variable, depending of the frequency and severity of microhemorrhage into the lesion (3). Cholesterol granuloma can be managed conservatively if there is minimal or no symptoms. When indicated, they can be drained surgically.