Brain Pathology Case of the Month - January 2012

DIAGNOSIS

Intradural schwannoma in schwannomatosis

DISCUSSION

Schwannomas are benign neoplasms of the peripheral nerve sheath that originate from the proliferation of Schwann cells and are typically well demarcated from surrounding tissue. Schwannomatosis has recently been recognized as a distinct tumor syndrome separate from NF-1 or NF-2 (1, 7-10). It is characterized by the presence of multiple schwannomas without the cutaneous stigmata, neurofibromas, or vestibular schwannomas (6, 12). Recent advances in medical genetics suggest inactivation of both SMARCB1 and NF2 genes could explain the cause of schwannomatosis (2, 3, 11).

The typical locations of schwannomas include spinal nerves, peripheral nerves, and multiple cranial nerves. Isolated involvement of a single limb (4) or a single nerve (5) by multiple schwannomas have also been reported. Here we report a case of schwannomatosis with multiple intradural, extramedullary lesions causing radiculopathy.

The goal of surgery is to obtain a diagnosis as well to remove symptomatic lesions as possible if clinical symptoms appear referable to a specific lesion. Complete surgical resection is generally not undertaken given the presence of multiple lesions throughout the spinal cord and/or cauda equina. Treatments for progressive lesions primarily include re-resection and radiation. Given her stable examination at present, this patient will undergo observation and be referred to medical genetics for further work-up.

REFERENCES

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  2. Boyd C, Smith M, Kluwe L, Balogh A, Maccollin M, Plotkin S (2008) Alterations in the SMARCB1 (INI1) tumor suppressor gene in familial schwannomatosis. Clin Genet.
  3. Hadfield KD, Newman WG, Bowers NL, Wallace A, Bolger C, Colley A, McCann E, Trump D, Prescott T, Evans DG (2008) Molecular characterisation of SMARCB1 and NF2 in familial and sporadic schwannomatosis. J Med Genet.45(6):332-9.
  4. Hasham S, Matteucci P, Stanley PR (2006) Schwannomatosis: multiple schwannomas of the upper limb. J Hand Surg [Br].31(2):182-4.
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  10. Seppala MT, Sainio MA, Haltia MJ, Kinnunen JJ, Setala KH, Jaaskelainen JE (1998) Multiple schwannomas: schwannomatosis or neurofibromatosis type 2? J Neurosurg.89(1):36-41.
  11. Sestini R, Bacci C, Provenzano A, Genuardi M, Papi L (2008) Evidence of a four-hit mechanism involving SMARCB1 and NF2 in schwannomatosis-associated schwannomas. Hum Mutat.29(2):227-31.
  12. Westhout FD, Mathews M, Pare LS, Armstrong WB, Tully P, Linskey ME (2007) Recognizing schwannomatosis and distinguishing it from neurofibromatosis type 1 or 2. J Spinal Disord Tech.20(4):329-32.

Contributed by Ning Lin, MD, Yao Lu, Anita Huttner, MD, PhD, Paul Spieler, MD, Elizabeth B. Claus, MD, PhD, Santosh Kesari, MD, PhD

International Society of Neuropathology