Supratentorial intraventricular schwannoma of the choroid plexus

Schwannoma supratentorial intraventricular do plexo coróideo

LETTER

Supratentorial intraventricular schwannoma of the choroid plexus

Schwannoma supratentorial intraventricular do plexo coróideo

Lucas Perez de Vasconcellos^I; Américo Rubens Leite dos Santos^II; José Carlos Esteves Veiga^III; Igor Schilemann^IV; Carmen Lúcia Penteado Lancellotti^V

^ISanta Casa Medical School, São Paulo SP, Brazil: MD, Medical Resident, Discipline of Neurosurgery

^IISanta Casa Medical School, São Paulo SP, Brazil: MD, Medical Instructor Professor, Discipline of Neurosurgery

^IIISanta Casa Medical School, São Paulo SP, Brazil: MD, Associate Professor, Discipline of Neurosurgery

^IVSanta Casa Medical School, São Paulo SP, Brazil: MD, Medical Resident, Department Pathology

^VSanta Casa Medical School, São Paulo SP, Brazil: MD, PhD, Full Professor, Department Pathology

Intraventricular tumours represent around 10% of central nervous system tumours¹. A variety of intraventricular tumours can be found, with the differential diagnosis depending upon the location in the ventricular system^2-4. In the lateral ventricles, the more common intraventricular tumours are meningiomas, astrocytomas and ependymomas, whereas choroid plexus papillomas and carcinomas, subependymomas and dermoid cysts are rare^3,5.

We report a case of intraventricular schwannoma of the choroid plexus in the lateral ventricle, presenting with headache.

CASE

A 21-year-old female who had been previously healthy with no significant past medical history presented with a constant, dull, aching generalized four-week headache without improvement after conservative treatment. Brain MRI (Fig 1) revealed a solitary 4 cm mass centred on the trigone of the lateral ventricle. The lesion appeared to have a pedicle attached to the choroid plexus of the left lateral ventricle. A diagnosis of choroid plexus papilloma was made due to its aspect and location.

On examination, the patient was awake and alert and normal upon neurological examination; in particular, there were no features of increased intracranial pressure. There was no stigmata of a neurocutaneous syndrome and there was no history in her family of inheritable neurological disorder, such as neurofibromatosis.

She underwent a left parietal craniotomy and transcortical microsurgical excision of the mass. The operatoty findings were of an encapsulated mass arising from the choroid plexus of the left lateral ventricle. There was a good plane around it and a complete resection was achieved with progressive circumferential mobilization around its margins. Postoperatively she awoke without any deficits. She was later discharged on day 7, remains well and returned to normal social activities.

Histological examination of the resected specimen (Fig 2A) was typical of schwannoma surrounded by choroid plexus. There was a tumour composed of neoplastic Schwnan cells, and forming two basic patterns in varying proportion: areas of compact, elongated cells with occasional nuclear palisading (Antoni A pattern) and less cellular, loosely textured cells with indistinct processes and variable lipidization (Antoni B). The tumour cells were strongly and diffusely expressed with S-100 protein (Fig 2B), and expressed GFAP focally (Fig 2C).

Further management was discussed in the setting of a multidisciplinary group, where no further adjuvant treatment was elected. Serial imaging was performed, and a brain MRI 3 months after resection, showed no evidence of a residual or recurrent tumour.

DISCUSSION

Schwannomas account for approximately 8% of all intracranial neoplasms⁶ . Most originate from the vestibular portion of the cranial nerve (CN) VIII. Others arise from the sensory fibers of CN V, VII, IX and XI. Nerve fibers of the central nervous system are not invested with a Schwann cell covering. Therefore, the occurrence of a nerve sheath tumour in central nervous tissue is unexpected^1.2. There are eleven case reports of ventricular schwannomas^3,7-9. The majority of these were located in either the lateral or fourth ventricles^4-7. Most reported intraventricular schwannomas have been benign, with only two demonstrating malignant features^7,8 (Table).

Several theories attempt to explain the origin of intraventricular schwannomas. In 1874, Benedickt³ identified nerve fibers in the choroid plexus of the fourth ventricle, an observation that was confirmed by Stohr¹⁰ in 1922, suggesting that neoplastic transformation of these Schwann cells could result in an intraventricular schwannoma.

As the autonomic nerves are associated with Schwann cells, this has led to the theory that primary intraventricular schwannomas may arise from the autonomic nervous tissue of the plexus choroids^3-8. It has also been suggested that intra-axial schwannomas could arise from neural crest cells displaced into the nervous system as a result of failed migration in embryonic life¹. This disordered embryogenesis theory may account for the relationship between intraventricular schwannomas and other neurocutaneous syndromes such as neurofibromatosis, Hirschprung's disease, and Waardenburg's syndrome^3,6.

Schwannomas are usually solitary, unless associated with a specific genetic syndrome. Most schwannomas have aberrations of cromossome 22. This presumably leads to suppression of the neurofibromin 2 gene product, merlin, located at band 22q12. Genetic syndromes are suggested by the presence of either unusual histologic variants of schwannoma and multiple schwannomas. Plexiform schwannoma and schwannomatosis are characteristic of neurofibromatosis type II³.

Tumours of the lateral ventricle commonly include meningiomas, ependymomas, choroid plexus papillomas and carcinomas, and astrocytomas. It is difficult to distinguish these from schwannomas based on imaging alone⁴.

In summary, intraventricular schwannomas are rare tumours that may be indistinguishable from other benign intraventricular lesions on imaging. When possible, total resection is the treatment of choice, particularly if the lesion is causing mass effect or neurologic symptoms, as was done in this rare case of a supratentorial intraventricular schwannoma arising from the choroid plexus, shown by the histological examination.

Received 11 February 2009, received in final form 17 July 2009. Accepted 7 August 2009.

Dr. Lucas Perez de Vasconcellos - Rua Desembargador Joaquim Barbosa de Almeida 368 - 05463-010 São Paulo SP - Brasil. E-mail: [e-mail]

• 1. Dow GR, Hussein A, Robertson IJ. Supratentorial intraventricular schwannoma. Br J Neurosurg 2004;18:561-562.
• 2. Barbosa MD, Rebelo O, Barbosa P, Gonçalves J, Fernandes R. Cystic intraventricular schwannoma: case report and review of the literature. Neurocirugia (Astur) 2001;12:56-60.
• 3. Benedict WJ Jr, Brown HG, Sivarajan G, Prabhu VC. Intraventricular schwannoma in a 15-year-old adolescent: a case report. Childs Nerv Syst 2008;24:529-532.
• 4. David M, Guyot JF, Ballivet J, Sachs M. [Schwannoid tumor of the lateral ventricle]. Neurochirurgie 1965;11:578-581.
• 5. Morrison G, Sobel DF, Kelley WM, Norman D. Intraventricular mass lesion. Radiology 1984;153:435-442.
• 6. Erdogan E, Onguru O, Bulakbasi N, Baysefer A, Gezen F, Timurkaynak E. Schwannoma of the lateral ventricle: eight-year follow-up and literature review. Minim Invasive Neurosurg 2003;46:50-53.
• 7. Jung JM, Shin HJ, Chi JG, Park IS, Kim ES, Han JW. Malignant intraventricular schwannoma. Case report. J Neurosurg 1995;82:121-124.
• 8. Leveque M, Gilliard C, Godfraind C, Ruchoux MM, Gustin T. [Intraventricular schwannoma: a case report]. Neurochirurgie 2007;53:383-386.
• 9. Messing-Junger AM, Riemenschneider MJ, Reifenberger G. A 21-year-old female with a third ventricular tumor. Brain Pathol 2006;16:87-93.
• 10. Stohr P. Ueber die Innervation des Plexus choroideus des Menschen. Z Gesamte Anat 1922;63:562-607.

Publication Dates

• Publication in this collection
  17 Dec 2009
• Date of issue
  Dec 2009