Spinal Intradural Extramedullary Schwannomas Mimicking Intramedullary Tumors: A Case Series.

Spinal schwannomas are among the most common intradural extramedullary tumors, together with meningiomas. Three cases of spinal schwannoma that presented predominantly with a cystic component and preoperative magnetic resonance imaging (MRI) findings mimicking those of intramedullary tumors were reported. The lesions were located at the C5-6, C7-T1, and T8-9 levels in one patient each. In all three patients, the lesions were located on the dorsal aspect of the spinal cord and compressed the spinal cord. MRI showed hyperintensity on T2-weighted images, with internal septal and nodular hypointense structures within the thoracic-level lesion. On T1-weighted images, hypointensity relative to the spinal cord was seen. In patients with lesions in the cervical and cervicothoracic level, postcontrast T1-weighted images revealed cystic components that showed no enhancement, while enhancement was observed along the cyst walls. In the patient with a lesion at the thoracic level, a cystic component and internal linear enhancement were seen, and the enhancement pattern differed from that observed in the other two cases. MR myelography (MRM) was performed in two patients, which helped delineate the extramedullary location of the lesions and their relationship with the spinal cord. In each case, a diagnosis of intradural extramedullary schwannoma was made based on surgical and pathological findings. Many spinal schwannomas are intradural extramedullary and arise from a dorsal root of the spinal cord. Large lesions often show cystic degeneration and heterogeneous internal enhancement. In all three cases described, a cystic component was present, and enhancement consistent with a cyst wall was observed on postcontrast T1-weighted images. Internal linear enhancement was observed in the patient with a thoracic vertebral lesion. Although enlargement of the intervertebral foramen is frequently associated with spinal schwannoma, it was absent in these cases. Rather, these patients had intramedullary tumor-like findings. In conclusion, the presence of a cystic mass on the dorsal aspect of the spinal cord should raise suspicion for spinal schwannoma and may serve as a useful feature for differentiating it from an intramedullary tumor with cystic components. These three cases are valuable because they illustrate the characteristics of spinal schwannomas with cystic components.