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Neuroradiology Case of the Week

Case 269

Ashwani K. Sharma, MD, Brian Sorensen, M.D.,
and P-L Westesson, MD, PhD, DDS

Clinical Presentation: Patient is a 24-year-old male with a brief history of severe back pain. His pain had been increasing and he had been to the emergency department twice for severe back pain. His neurologic exam was remarkable for patchy hypesthesia in the left anterior thigh. He had an intact motor exam.

Imaging Findings: MRI of the spine reveals a well-defined intradural extramedullary cystic mass lesion at the level of the L2-L3 vertebral level without surrounding flow voids.

Differential diagnosis includes cystic schwannoma, epidermoid/dermoid cystic meningioma, and meningocele.

Diagnosis: Cystic schwannoma

Discussion: Schwannomas are slow growing benign tumors. They are usually encapsulated, and rarely undergo malignant transformation [1]. Benign schwannomas can occasionally display degenerative changes that are encompassed by cyst formation, calcifications, hemorrhage and hyalinization. The lumbar region is one of the most common sites for occurrence of spinal schwannomas [2]. While schwannomas occurring within the lumbar spine are not rare, large and predominantly cystic schwannomas occurring in the lumbar spine have scantly been demonstrated, even though it is well defined that benign schwannomas can eventually display degenerative changes defined by cyst formation, calcification, hemorrhage and hyalinization [1]. Interestingly, large schwannomas within the lumbar spine may go unnoticed for a large time span mainly due to the indolent growth of the tumor and the paucity of symptoms generated [3].

References:

1. Kleihues, P., and Cavenee, W.K. (Eds.) Pathology and Genetics of Tumours of the Nervous System. Lyon, France: International Agency for Research on Cancer, 1997 pp. 171-193.
2. Conti P, Pansini G, Mouchaty H, Capuano C, Conti R. Spinal neurinomas: retrospective analysis and long-term outcome of 179 consecutively operated cases and review of the literature. Surg Neurol. 2004 Jan;61(1):34-43; discussion 44. [Medline]
3. Borges G, Bonilha L, Proa M Jr, Fernandes YB, Ramina R, Zanardi V, Menezes JR. Imaging features and treatment of an intradural lumbar cystic schwannoma. Arq Neuropsiquiatr. 2005 Sep;63(3A):681-4. Epub 2005 Sep 9. [Medline]