Neurofibromatosis II: A Disease of Multicentric Central Nervous System Masses
1Department of Radiodiagnosis, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India
2Department of Physiology, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India
3Department of Radiodiagnois and Imaging, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India
Corresponding Author: Arvinder Singh, Department of Radiodiagnosis, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India, Phone: +91 9878655028, e-mail: firstname.lastname@example.org
How to cite this article: Singh A, Kaur M, Kaur S. Neurofibromatosis II: A Disease of Multicentric Central Nervous System Masses. AMEI’s Curr Trends Diagn Treat 2021;5(2):110–113.
Source of support: Nil
Conflict of interest: None
Neurofibromatosis (NF) is an autosomal dominant disorder with two reported types. Neurofibromatosis type I presents with the cutaneous manifestations and involves astrocytes and the neurons. Neurofibromatosis II involves meninges and the Schwann cells in the central nervous system with presentation as bilateral schwannomas, multiple meningiomas, and cord ependymomas.
Our present case was presented with bilateral hearing loss and chronic headache. MRI of the brain showed bilateral vestibular schwannomas extending up to bilateral cerebellopontine angle cisterns, mass lesion in relation to the right trigeminal nerve, multiple extra-axial dura-based mass lesions, posterior fossa mixed signal lesion, optic nerve sheath tumors, and two intradural intramedullary cervical cord ependymomas with surrounding cord edema.
Keywords: Magnetic resonance imaging, Neurofibromatosis, Schwannomas.
Neurofibromatosis (NF) consists of genetic disorders in which there are benign and malignant tumors of the nervous system.1 It is classified into two types, i.e., NF-I and NF-II, and may involve brain, spinal cord, and exiting nerves, bones, soft tissue, kidneys, and the mediastinum.2
Neurofibromatosis type I was first found by von Recklinghausen in 1882. This disorder was presented with neurocutaneous tumors and vasculitis. Neurofibromatosis type II is a relatively rare disorder, presenting frequently with central nervous system tumors.3
Notably, several patients have a range of organs affected as there is an extreme prevalence of multiple tumors happening in the same patient.2 The diagnostic imaging techniques with precise clinical diagnosis help in distinguishing the above two types.1 Magnetic resonance imaging (MRI) is the best imaging modality for the diagnosis and management of neurofibromatosis type I and II.4
An 18-year-old male presented us with a history of progressive bilateral hearing loss, diminished visual acuity on the left side, chronic headache, vertigo, and past history of seizures since 1 year. He was normotensive, afebrile, and the pulse rate measured was 72 bpm at the time of general physical examination. There was no focal neurological deficit.
MRI brain showed mass lesions in relation to bilateral internal auditory canal causing their widening and extending into bilateral cerebellopontine (CP) angle cisterns. These lesions were hypointense on T1W and hyperintense on T2W images and showed intense postcontrast enhancement (Fig. 1). The lesion on right side measured about 2.2 × 1.0 cm and 2.0 × 1.0 cm on left side. About three dura-based extra-axial lesions were seen, one in right frontal and one each in parietal regions, appearing hypointense on T1W and hyperintense on T2W images with avid contrast uptake on T1 postcontrast images (Fig. 2). A well-defined homogeneously enhancing lesion was also seen in relation to the cisternal segment of the right trigeminal nerve which was not seen separately from this mass (Fig. 3).
A solid cystic mass lesion measuring about 3.0 × 2.8 × 2.0 cm in size was seen in relation to the right cerebellar hemisphere abutting the fourth ventricle. The cystic component appeared hyperintense on T2W images and hypointense on T1W images. The solid component appeared heterogeneous on T2W images and T1W images and showed variable enhancement on postcontrast images (Fig. 4).
A T2W hyperintense mass lesion was seen around the left optic nerve measuring 2.0 × 1.7 cm in size which showed significant enhancement on the postcontrast study. The optic nerve was seen traversing through the lesion (Fig. 5).
MRI evaluation of cervical spine revealed two intramedullary lesions opposite to C2 and C3 vertebral bodies, appearing isointense to hypointense on T1W, isointense to hyperintense on T2W images, and showed homogeneous enhancement on postcontrast study (Fig. 6).
Neurofibromatosis (NF) is an autosomal dominant disease with involvement of the cutaneous, nervous, and musculoskeletal systems.5 It may manifest immediately after birth or later in the life.2 It has been classified into two types, with chromosome 17 in NF-I and defect in chromosome 22 in NF-II.5
NF-I has a tumor-suppressor gene that encodes the protein neurofibromin, which normally regulates the cell growth and differentiation. NF-II encodes a tumor-suppressor gene which encodes the protein merlin that regulates the cell growth, especially the Schwann cells.3
NF-I involves multiple cell types and systems of the body.4 The NF1 presents with cafe-au-lait spots and various cutaneous lesions with the involvement of CNS in about 15% of cases. It consists of optic nerve gliomas, cerebral, and brainstem astrocytoma.2 The optic gliomas can affect any part of the optic pathway, with the involvement of one or both optic nerves.4
The most common benign neoplasms are neurofibromas with peripheral nerve sheath tumor as the most aggressive malignancy. The vascular abnormalities may involve the distal internal carotid and its branches. Skeletal manifestations consist of scoliosis, pseudoarthrosis of long bones, hemihypertrophy, and ribbon-shaped appearance of ribs.2
NF-II presents with CNS lesions like bilateral acoustic schwannomas occurring primarily in relation to the internal auditory canal in about 95% of adult patients.2,4 The definite diagnostic criterion for NF-II is bilateral vestibular schwannomas. Multiple meningiomas are reported in NF-II patients with variable size occurring in a younger age group.4,5 Infrequently, the patient may present with Bell’s palsy of the facial nerve.6
MR imaging findings in neurofibromatosis-I are often in the brain stem, cerebellum, and basal ganglia in the form of pilocytic astrocytomas, brain stem gliomas, plexiform neurofibromas, and orbital gliomas.3
Cervical spine ependymomas are usually centrally located within the cord and display an intense postcontrast enhancement.4
Our present case was presented with bilateral vestibular schwannomas, right and trigeminal mass multiple intracranial meningiomas, left optic nerve sheath meningioma, posterior fossa pilocytic astrocytoma, and two intramedullary cervical ependymomas. Though he had no family history, the presence of bilateral schwannomas is diagnostic for the NF-II syndrome, without the need for a biopsy.
The management of neurofibromatosis is by a multidisciplinary approach comprising surgery and radiotherapy.6 The schwannoma patients can be treated with bevacizumab, which produces tumor regression.8 Another option for small tumors is stereotactic radiotherapy. The intracranial meningiomas may be resected surgically except that of optic nerve sheath.6
There is quite variability of disease progression in neurofibromatosis.9 Due to various cranial and spinal neoplasms, there may be long-term morbidity and reduced life expectancy in NF-II patients. MRI scans are frequently required for management.9,10
The improved understanding of the clinical manifestations of neurofibromatosis in addition to better precision in neuroimaging and genetic tests has dramatically improved prompt diagnosis of patients. Early and correct diagnosis of the disease may be beneficial in preventing disabilities even in the next generation.
Sumanjeet Kaur https://orcid.org/0000-0003-3290-2909
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8. Kollmann P, Mautner VF, Koeppen J, et al. MRI-based volumetric measurements of vestibular schwannomas in patients with neurofibromatosis type 2: comparison of three different software tools. Sci Rep 2020;10(1). DOI: 10.1038/s41598-020-68489-y.
10. Rennie ATM, Side L, Kerr RSC, et al. Intramedullary tumors in patients with neurofibromatosis type 2: MRI features associated with a favorable prognosis. Clin Radiol 2008;63(2):193–200. DOI: 10.1016/ j.crad.2007.08.003.
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