Cystic spinal schwannoma

Various theories have been hypothesized to explain the cystic change occurring in schwannomas.

Degeneration of the Antoni B portion of a neuroma can result in cyst formation and may then progress to form a larger cyst ¹⁾ ²⁾.

Central ischemic necrosis, thrombosis of the vessels with resultant necrosis plus hemorrhage or tumor neovascularity also can be caused by tumor growth resulting in cyst formation within the tumor ³⁾

Though cystic changes in schwannomas are well described, predominantly cystic schwannomas are uncommon lesions and form a different spectrum of conditions as compared with the commonly seen intradural extramedullary solid lesions.

Savardekar et al. present a case series of six patients with spinal intradural extramedullary cystic schwannomas. Two patients had uniloculated cystic schwannomas, two patients had multi-loculated cystic lesions with thick walls and intralesional septations, and two patients had giant cystic schwannomas, one of which had an extradural extension. We report two cases in which preoperative radiological dilemma was encountered and discuss the differential diagnoses of this uncommon entity.

Cystic spinal schwannomas may be confused with other cystic lesions in the spine, differentiating them preoperatively is important and in this regard, contrast-enhanced magnetic resonance imaging plays a vital role. Frozen section histopathology should be used to identify them at surgery. It is important to detect these lesions at surgery, as total excision is possible and almost always results in good long-term neurological outcome ⁴⁾.

¹⁾

Parmar H, Patkar D, Gadani S, Shah J. Cystic lumbar nerve sheath tumours: MRI features in five patients. Australas Radiol 2001; 45: 123-127.

²⁾

Shiono T, Yoshikawa K, Iwasaki N. Huge lumbar spinal cystic neurinomas with unusual MR findings. AJNR Am J Neuroradiol 1995; 16 (4 Suppl): 881-882.

³⁾

Santhosh K, Kesavadas C, Thomas B, Gupta AK, Kapilamoorthy TR, Radhakrishnan VV. Fluid-fluid levels in cystic lumbosacral schwannomas: a report of three cases. Singapore Med J 2009; 50: e16-e21.

⁴⁾

Savardekar A, Singla N, Mohindra S, Ahuja CK, Gupta SK. Cystic spinal schwannomas: A short series of six cases. Can we predict them preoperatively? Surg Neurol Int. 2014 Aug 28;5(Suppl 7):S349-53. doi: 10.4103/2152-7806.139666. PMID: 25289159; PMCID: PMC4173214.