Abstract
Cholesterol granuloma is the most common primary lesion of the petrous apex. Management of petrous apex cholesterol granuloma has evolved in recent years from primary surgical treatment to conservative observation. In this article, a case of spontaneous resolution of a petrous apex cholesterol granuloma is described. To the authors’ knowledge, this is the first known report of spontaneous involution of a petrous apex cholesterol granuloma. Radiographic differential diagnosis of petrous apex lesions and the natural history of cholesterol granulomas are discussed.
1
Introduction
Cholesterol granulomas are the most common primary lesions of the petrous apex, comprising 60% of all pathology arising within this region . A large number of patients are diagnosed incidentally or after obtaining imaging for non-localizing headache. Management trends for these lesions have evolved over time, from routine surgery to primary observation with serial imaging. With this trend, natural history data has become increasingly important. Herein we report a case in which spontaneous resolution of a cholesterol granuloma of the petrous apex occurred.
2
Case
A 13-year-old boy was referred to a neurologist for a 4-month history of generalized fatigue and migraine headaches lasting 3–6 hours that were bilateral and had associated double vision. Cranial nerve exam was benign and extraocular movements were intact. Magnetic resonance imaging (MRI) was obtained which demonstrated a 1.5 × 0.8 cm left-sided cystic petrous apex lesion that was consistent with cholesterol granuloma ( Fig. 1 A and B ). Specifically, T1-weighted sequences revealed iso- to hyper-intense signal without contrast, and T2-weighted images demonstrated uniform hyperintense signal. Diffusion weighted imaging did not demonstrate restricted diffusion. Temporal bone computed tomography (CT) revealed an expansile lesion with smooth margins, and without erosion of the cochlea or petrous carotid canal ( Fig. 1 C).
The patient was subsequently referred to the authors’ center in 2012 for further evaluation and management. On examination, otomicroscopy revealed mild bilateral retraction of the pars flaccida without debris accumulation and an audiogram showed normal down sloping to mild conductive hearing loss bilaterally. After evaluation, the authors recommended serial imaging and medical therapy for migraine, which improved his symptoms. Follow-up imaging at 1.5 years showed no appreciable change in the lesion; however, his most recent MRI at 2.5 years from diagnosis showed complete resolution ( Fig. 2 ).
2
Case
A 13-year-old boy was referred to a neurologist for a 4-month history of generalized fatigue and migraine headaches lasting 3–6 hours that were bilateral and had associated double vision. Cranial nerve exam was benign and extraocular movements were intact. Magnetic resonance imaging (MRI) was obtained which demonstrated a 1.5 × 0.8 cm left-sided cystic petrous apex lesion that was consistent with cholesterol granuloma ( Fig. 1 A and B ). Specifically, T1-weighted sequences revealed iso- to hyper-intense signal without contrast, and T2-weighted images demonstrated uniform hyperintense signal. Diffusion weighted imaging did not demonstrate restricted diffusion. Temporal bone computed tomography (CT) revealed an expansile lesion with smooth margins, and without erosion of the cochlea or petrous carotid canal ( Fig. 1 C).
