Multiple intracranial lipomas, hypogenetic corpus callosum and vestibular schwannoma: an unusual spectrum of MR findings in a patient.J Shah, P Srinivasa, B Gala, D Patkar, T Patankar, H Kale
Department of Radiology, Dr Balabhai Nanavati Hospital, Vile Parle, Mumbai, India., India
Correspondence Address: Source of Support: None, Conflict of Interest: None PMID: 0010734334
Source of Support: None, Conflict of Interest: None
We describe imaging findings of a patient with multiple intracranial lipomas, hypogenetic corpus callosum and a vestibular schwannoma. We did not find association of intracranial lipomas and vestibular schwannoma in English literature.
Keywords: Adult, Brain Neoplasms, diagnosis,Case Report, Corpus Callosum, pathology,Cranial Nerve Neoplasms, diagnosis,Female, Human, Lipoma, diagnosis,Neoplasms, Multiple Primary, diagnosis,Neurilemmoma, diagnosis,Vestibular Nerve, Vestibulocochlear Nerve Diseases, diagnosis,
Intracranial lipomas are extremely rare, comprising 0.1% to 0.5% of all primary brain neoplasms. Pericallosal lipomas, which constitute the commonest variety of intracranial lipomas, are frequently associated with varying degree of dysgenesis of the corpus callosum. Schwannomas are benign schwann cell neoplasms accounting for approximately 6% to 8% of primary intracranial tumours. Vestibular schwannoma is the commonest cerebellopontine angle cistern mass and accounts for roughly 75% of all lesions at this site.
A thirty-year-old-woman presented with an eight months history of tinnitus and progressive hearing loss in her right ear. She had two episodes of generalised tonic-clonic seizures five months back. Clinical and audio-logical examination revealed profound sensorineural hearing loss on her right side. Rest of the neurological examination was non-contributory. There were multiple subcutaneous lipomas in both the upper extremities. There were no features suggestive of neurofibromatoses. Triplanar spin-echo and Gadolinium enhanced magnetic resonance (MR) examination of the brain was performed. MR showed a large, pericallosal lipoma, multiple choroid plexus lipomas, a dysgenetic corpus callosum, absent septum pellucidum and a large cerebello-pontine angle mass lesion with intracanalicular extension [Figure - 1], [Figure - 2]. The cerebellopontine angle mass was hypointense on T1 WI, hyperintense on T2 WI and showed marked contrast enhancement [Figure - 3], [Figure - 4]. The imaging characteristics suggested a vestibular schwannoma. The patient underwent surgical resection of the vestibular schwannoma and made an uneventful recovery. The patient is currently on active follow-up.
Intracranial lipomas represent rare developmental malformations of the nervous system. They result from lipomatous differentiation of the persistent meninx primitiva, the mesenchymal derivative of the embryonic neural crest which envelopes the developing embryo,. Since lipomas are postulated to develop in areas of tardy / incomplete resorption of the meninx primitiva (the cavitation of which result in formation of subarachnoid space), vessels and cranial nerves frequently traverse these malformations.
Lipomas are usually found in close apposition to the subjacent brain tissue. Lipomas do not grow; however they hypertrophy in tandem with the somatic growth.
Inter-hemispheric lipomas constitute 40% to 50% of intracranial lipomas and are frequently associated with dysgenetic corpus callosum. Other associated findings include encephalocele, focal parenchymal hypoplasia, absent septum pellucidum and lipomas at other sites.
Typical clinical manifestations include seizures and headache. Intracranial lipomas especially the interhemispheric lipomas have been described in patients with midline craniofacial anomalies.
Choroid plexus lipomas of the lateral ventricle occur frequently in association with pericallosal lipomas. The primitive meninx follows the choroidal fissure (to which the developing choroid plexus is attached to) into the lateral ventricle, thus contributing to the choroidal lipomas.
Intracranial schwannomas have a distinct predilection to involve sensory nerves. Vestibular divisions of the vestibulo-cochlear nerve constitute the most common target sites for schwannomas. Early symptoms of vestibular schwannomas include tinnitus and sensorineural hearing loss. Later, patients manifest symptoms due to brainstem, nerve compression and obstructive hydrocephalus. Bilateral vestibular schwannomas are pathognomonic of neurofibromatosis type-2.
Intracranial lipomas have also been described as a component of encephalocraniocutaneous lipomatosis, an extremely rare neurocutaneous syndrome,. This rare syndrome is characterised by subcutaneous lipomas of the scalp and neck, intracranial and intraspinal lipomas, leptomeningeal lipogranulomatosis and a host of ophthalmic, cerebral parenchymal and vascular malformations. Congenital cerebral abnormalities include microgyria, atrophy, porencephaly and parenchymal / leptomeningeal calcifications. Sinha et al have documented the occurrence of an intraspinal lipoma in a patient with neurofibromatoses- 1. Amonkar et al described an unusual variant of melanocytic phacomatoses which they postulated to be a cross between encephalo-craniocutaneous lipomatosis and neurocutaneous melanosis. They reported cystic, frontal astrocytoma in association with bilateral cerebello-pontine angle lipomas.
Our case might either represent an unusual variant of neurofibromatosis (though characteristic features of the disease were absent) or a variant of encephalocraniocutaneous lipomatosis (in the absence of cerebral parenchymal, leptomeningeal and ophthalmic abnormalities). Our literature search failed to reveal the spectrum of findings as seen in our patient.
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]