What Is Lipoma?
Nervous system lipomas are uncommon, non-cancerous fatty tissue masses. They are birth defects instead of genuine tumors, and they may be linked to other nervous system abnormalities at birth. One can find lipomas in the brain or spinal cord, and they differ in size. There could be one tumor or several.
What Are Intracranial Lipomas?
Intracranial lipomas are clusters of fatty tissue deposited in the intracranial cavity and cerebrospinal fluid spaces. These are not cancerous growths and are believed to be abnormalities resulting from the differentiation of the defective embryological meninx primitiva (the bundle of mesenchyme and neural crest that envelopes the growing brain during pregnancy). Intracranial lipomas are asymptomatic, but sometimes, individuals with this condition might experience headaches and seizures. The types of lipoma, depending on the site of occurrence, include peri callosal lipomas (present in the interhemispheric fissure), quadrigeminal lipomas (present in the quadrigeminal cistern), suprasellar cistern lipomas (found in the suprasellar region), cerebellopontine angle lipomas (a rare form of lipoma), Sylvian fissure lipomas (one of the most uncommon forms of intracranial lipomas), and choroid plexus lipomas (a type of lipoma present in choroid plexus region).
What Are the Signs and Symptoms of Intracranial Lipomas?
Most lipomas are not associated with any symptoms at all. Intracranial lipomas have been linked to cranial nerve impairments, psychomotor delay, headaches, and seizures. Quadrigeminal plate lipomas have been linked to hydrocephalus (collection of cerebrospinal fluid within the brain), and Sylvian fissure lipomas seem to be linked to epilepsy. The majority of big lipomas are linked with abnormalities that, in addition to callosal dysgenesis (partial or complete absence (agenesis) of corpus callosum), cause symptoms such as the absence of septum pellucidum (a thin membrane in the brain), aqueductal stenosis (cerebral aqueduct constriction), and cortical deformities.
What Are the Imaging Features of Intracranial Lipomas?
A distinctive finding in both computed tomography (CT) and magnetic resonance imaging (MRI) is a lump that resembles fat.
Computed Tomography:
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With the use of specialized X-ray devices, computed tomography (CT) is a non-intrusive imaging technique that produces finely detailed images, or scans, of internal body tissues. Every image produced by a CT scan displays the bones, organs, and other tissues in a slender "slice" of the body.
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They usually show up on CT as a consistently dense mass of non-enhancing fat. With its lobulated soft look, it blends in with the surrounding anatomy. There can be some calcification in the margin.
Magnetic Resonance Imaging:
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A simple imaging method that creates three-dimensional, finely precise anatomical images is called magnetic resonance imaging (MRI).
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Both fat saturation and non-fat saturation MRIs can readily diagnose illness. The chemical shift effect might be helpful if there are no fat-saturated pictures. Certainly, the signal's properties are similar to those of fat.
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In T1- and T2-weighted images, it produces high signal strength.
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In T1-weighted post-gadolinium images, it shows no enhancement.
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In fat-saturated images, it produces low signal strength.
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It is best to view the lipomas on high-resolution sequences as they are frequently crossed by nearby arteries and cranial nerves.
What Are the Specific Imaging Characteristics of Pericallasol Lipoma?
Based on imaging, pericallosal lipomas can be divided into two different types, namely tubulonodular and curvilinear.
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Tubulonodular Lipoma: The most prevalent type of pericallosal lipomas is tubulonodular. Their thickness typically exceeds 0.79 inches, and they are either lobular or spherical. They are located anteriorly and are linked to fronto-facial abnormalities and significant callosal defects. The tubulonodular variant has the ability to spread into the lateral ventricles and choroid plexus.
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Curvilinear Lipoma: Typically, curvilinear pericallosal lipomas are thin, extended, and located at the border of the corpus callosum. They are often located more posteriorly and have a thickness of less than one centimeter. A correlation with extracranial subcutaneous lipomas is observed in a tiny proportion of cases of pericallosal lipomas. This might be because of the presence of an abnormality in the skull, like cranium bifidum where the lipomas can connect, or they may be continuous, utilizing a thin stalk extending across a healthy cranial vault.
Ultrasound:
In the area of the corpus callosum, ultrasound shows the distinctive appearance of fat as a hyperechoic midline mass.
Computed Tomography:
CT is a diagnostic tool that shows the mass of fat. Furthermore, the tubulonodular variation may exhibit peripheral curvilinear calcification, often known as the bracket sign. The anterior cerebral arteries, which ascend through or on top of the mass, may be related to vascular abnormalities or the establishment of aneurysms. Thus, CT angiography might be necessary.
Magnetic Resonance Imaging:
This is the preferred method for determining the extent of lipoma. It also helps identify the agenesis or dysgenesis of the corpus callosum.
What Is the Differential Diagnosis?
The differential diagnosis includes conditions that are growths containing fatty tissue.
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Intracranial Dermoid - Although intracranial dermoid cysts are rare, every individual will have a different set of clinical characteristics and surgical outcomes. Although dermoids are mostly non-cancerous, based on where they are, they might rupture and result in consequences, including meningitis or hydrocephalus, as well as epileptic seizures.
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Intracranial Teratoma - These are intracranial tumors that can manifest in a variety of ways. They are broadly classified into mature, immature, and mature with neaplastic changes. Teratomas are also categorized into intra-axial and extra-axial, depending on their signs and symptoms.
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Ependymoma - Ependymomas originate from the brain's ventricles or the spinal cord's central canal.
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Glioma - This condition occurs when glial cells proliferate excessively. It primarily affects the brain and spinal cord. Gliomas are categorized into three types. They are astrocytoma, ependymoma, and oligodendroglioma.
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Primitive Neuroectodermal Tumor of the Central Nervous System - These are aggressive tumors mostly affecting children.
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Fatty Falx Cerebri - A non-cancerous growth that is situated usually in the extradural neural axis area.
How Are Intracranial Lipomas Treated?
Most intracranial lipomas are without symptoms, and they do not require treatment. Treatment is generally not required, even in situations associated with conditions that cause symptoms. If surgery is done to address the lipoma, the rate of morbidity is relatively higher than the benefit it provides. This is because of the vascular nature and its attachment to the nearby brain tissue. The specific treatment must be given if hydrocephalus or seizures are present.
Conclusion:
Intracranial lipomas are uncommon congenital growths and do not exhibit any symptoms. They are usually identified by accident in CT or MRI imaging. Some lipomas may present with headaches and dizziness, and they may cause seizure disorders. Most of the time, lipomas do not require any treatment, and if there are any associated symptoms, they should be managed.
