Intradural extramedullary cavernoma of a lumbar nerve root mimicking neurofibroma. A report of a rare case and the differential diagnosis.

Background Context: Intradural extramedullary (IDEM) cavernomas are rare vascular malformations. They are well-circumscribed dark berry-like lesions with a histologic appearance of sinusoidal vascular channels. Neurofibromas are the most common IDEM tumors, originating from all nerve elements and leading to firm enlargement of the affected nerve root. These lesions are completely different; however, they may involve the spinal nerve roots or the major nerve trunks. Any similarities in clinical findings are based on different pathophysiology.
Purpose: To present a rare resemblance of an IDEM cavernoma to a neurofibroma.
Study Design: This is a case report with review of the literature focused on the differential diagnosis.
Methods: A 79-year-old patient presented with acute sensorimotor disturbance from L2-S1 levels. The investigations showed an L2-L3 lesion occupying the canal. Findings resembled a neurofibroma and a surgical resection was decided.
Results: The complete surgical resection revealed a vascular lesion originating from a nerve root. The histology confirmed an IDEM cavernoma. This is a unique case as such a clinical resemblance and a macroscopical appearance has not been reported for an IDEM cavernoma as yet. The patient showed full postoperative recovery from his initial symptoms.
Conclusions: Intradural extramedullary cavernoma is a rare cause of compression to spinal cord or nerve roots. Its manifestation characteristics are well defined and should always be part of the differential diagnosis. Intraoperative findings aid the diagnosis in nontypical cases before the final histology. The nontraumatic and nerve tissue sparing surgical resection warrants optimal postoperative results and excellent prognosis.
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