Bilateral cholesterol granuloma: an unusual presentation as an intradural mass.

The origin of the cholesterol granuloma is controversial; however, it is believed to result from an inflammatory response of the temporal bone to an obstruction of the pneumatized air cells. Hemorrhage into the air cells results in a foreign-body reaction and progressive granuloma formation. As the process develops, bone is eroded by this expansile lesion, often involving the middle ear, the petrous apex, and the cerebellopontine angle. We present the first reported case of cholesterol granulomas manifesting as bilateral intradural lesions adjacent to the temporal lobes. The fact that it presents bilaterally with sclerotic mastoids makes this presentation even more unique. Its location might cast controversy on the existing theories of development. A literature review of the cholesterol granuloma will be discussed, relating it to this patient's unusual presentation.