Spinal Schwannomatosis Mimicking Metastatic Extramedullary Spinal Tumor

Abstract

Intradural extramedullary (IDEM) tumors are the most commonly observed intraspinal tumors, comprising over 60% of tumors found within the spinal canal, and the vast majority of these lesions are benign lesions. IDEM metastases are rare, but if they occur, they commonly manifest as leptomeningeal disease, secondary to drop lesions from intracranial metastases from adenocarcinomas of the lung, prostate cancer, breast cancer, melanoma, or rarely, as a result of lymphomas. The purely non-neurogenic origin of IDEM metastases is rare. Herein, we describe a patient with a previous history of treated colon cancer who presented with a progressive neurological deficit and whose imaging revealed multiple intradural, extramedullary and osseous lesions at the cervical and thoracolumbar spines. With the previous known primary and multiplicity of the lesions, an initial diagnosis of spinal metastasis was made, But it was proven to be schwannoma on histology. We emphasize the diagnostic dilemma in this case and the importance of detecting subtle imaging findings, which may be helpful to differentiate between metastatic disease and a second primary tumor.

Keywords: extramedullary; hemangioma; intradural; metastases; schwannoma.

Figure 1

T2WI (a,b) sagittal images of thoracic and upper lumbar spine showing multiple (white arrows) intradural extramedullary lesions at T11, T12 and T12/L1 levels. Gadolinum-T1FS sequence in sagittal (c) and axial (d–f) planes showing enhancement of all these lesions.

Figure 2

Images of cervical spine showing an intradural extramedullary lesion (white arrow) at the level of C4–C5. It demonstrates hyperintense signal on T2WI (a), intermediate signal on T1WI (b) and avid enhancement on gadolinum-T1FS sequence (c,e). This lesion causes spinal cord compression at this level with associated spinal cord T2WI hyperintense signal indicating of cord oedema (a). Right parasagittal image (d) showed extension into the right C4 neural foramina (e).

Figure 3

Sagittal images (a–d) at T8 to T10 level showing lesion (white arrow) at T9 vertebral body demonstrating hyperintense signal on T1WI (a) and T2WI (b) with signal suppression on fat saturation sequence (c) and minimal enhancement on post contrast sequence (d), typical of hemangioma. Coronal bone algorithm CT shows classic corduroy sign in hemangioma at T9 vertebral body (e). Sagittal plane of thoracolumbar spine (f) of ¹⁸F-FDG PET/CT also showed reduced FDG metabolism of the T9 lesion (white arrow) with no FDG avid lesion seen at the thoracolumbar spine to suggest metastasis. Another small lesion (arrowhead) at T10 vertebral body which is isointense on T1WI (a), hyperintense on T2WI (b) with enhancement on post contrast sequence (d).