Intracranial lipomas: importance of localization

Abstract

Intracranial lipomas are rare congenital malformations. They are usually pericallosal asymptomatic midline lesions. Other brain malformations are often seen in association with intracranial lipomas. We describe the findings of imaging studies, including computed tomography (CT), magnetic resonance (MR) imaging, and MR angiography, along with a brief review of the literature. The frequency and the spectrum of the associated brain malformations are also discussed. We retrospectively reviewed CT and MR findings of 24 patients (14 female, 10 male, mean age 38.6 years) diagnosed with intracranial lipoma between December 2000 and June 2004 in two different radiology departments. Seventeen of the patients were diagnosed using cranial MR and seven with cranial CT. The CT density of all lesions was measured. Imaging characteristics of lipomas, morphological findings and associated malformations were described. The intracranial locations of the lipomas were left-sided quadrigeminal cistern (n=3), right-sided quadrigeminal cistern (n=4), interpeduncular cistern (n=1), sylvian fissure (n=3), interhemispheric fissure (n=3), choroid plexus (n=2), intercerebellar fissure (n=3), corpus fornicis (n=1) and the periphery of the corpus callosum (n=4). Eighteen of the intracranial lipomas were tubulonodular; six were curvilinear. Associated anomalies were observed in six patients. All of the patients with sylvian fissure lipoma had seizures. The two preferential sites of intracranial lipomas were pericallosal and dorsal mesencephalic. Most intracranial lipomas are found incidentally during neuroradiological investigations. CT and MR examination usually lead to the diagnosis, because of the very low attenuation values of lipomas on CT and the short T1 and T2 on MR. Midline anomalies and other malformations such as aneurysms are frequently associated with intracranial lipomas. Careful radiologic evaluation is therefore necessary to evaluate associated pathologies. Sylvian fissure lipomas should be considered in the differential diagnosis of patients with epilepsy.

Small Intracranial Lipomas may be a Frequent Finding on Computed Tomography of the Brain

“…were larger than those detected in this case series 3,5 . One might speculate that there is a continuum of findings with larger lipomas indicating a more disturbed brain formation explaining the high frequency of associated brain malformations.…”

Cerebellopontine angle lipomas: magnetic resonance imaging findings in two cases

“…The CT scan demonstrates a marked hypodense nonenhancing lesion in the CPA, with attenuation characteristics similar to adipose tissue (-40 to -100 HU) 1,5,9,10 . Regarding the MR imaging findings, lipomas have signal characteristics similar to the subcutaneous tissue, with high-signal intensity on T1-weighted images, and iso-to hypointense signal on T2-weighted images, usually without contrast enhancement 1 .…”

“…The patient signed the informed consent agreeing with the study. diSCuSSion Intracranial lipomas are rare lesions, corresponding to less than 0.1% of all intracranial tumors 3,10,11 . Some authors have suggested that lipomas are congenital malformations because their lack of cellular atypia, dysplasia and other evidences of malignancy, as well as due to the fact that they are usually associated to other malformations 4,7,11 .…”

“…Clinically, CPA lipomas can cause slowly progressive neurological symptoms and signs affecting cranial nerves or brain stem 3,[6][7][8] . Because these lesions usually are strongly attached to the surrounding structures, any surgical attempts of complete resection can result in neural or vascular damage, reinforcing the importance of the pre-operative imaging diagnosis [1][2][3]7,9,10 . Although the CT findings of CPA lipomas can be typical, the magnetic resonance (MR) imaging, especially the fat suppression sequences, had improved the identification of these lesions.…”

Lipomas of quadrigeminal cistern: report of 12 cases with clinic and radiologic features

“…Lipomas make up only 0.1-0.5% of intracranial lesions (14,15). They tend to be placed at the midline, most commonly in the pericallosal cistern (1,6,14).…”