Diagnostic value of MRI in coexistence of schwannoma and meningioma mimicking a single dumbbell-shaped tumor in high cervical level. Case series and literature review.

Context: Concurrent schwannoma and meningioma arising in the high cervical level mimicking a single dumbbell-shaped tumor is significantly rare, most of them were found during the surgeries or postoperative histological findings unexpectedly. The specific feature of schwannoma and meningioma coexistence in high cervical level on MR images has not been clearly described yet.
Findings: We presented four cases of concurrent extradural schwannoma and intradural meningioma mimicking a single dumbbell-shaped tumor arising in the high cervical level. There was no interconnection between intradural and extradural masses in any case. In MRI reviews, the signal intensity between intradural lesions and spinal cord was similar on T2 weighted MR images. However, on contrast-enhanced MR images, the intradural lesions were more enhanced than spinal cord and presented as crescent-shaped intradural minor lesions adjacent to the more significantly enhanced extradural major tumor. These MRI findings could not be easily identified without meticulous observation preoperatively. Postoperative pathological findings confirmed the discrete tumors arising in the same cervical level.
Conclusion: The comparison of signal intensity changes among the spinal cord, intradural tumor and extradural tumor between T2 weighted and contrast-enhanced MR images may be helpful to predict coexistent schwannoma and meningioma in the high cervical level preoperatively. Intradural exploration is highly recommended when less enhanced crescent-shaped intradural minor lesion was observed adjacent to the significantly enhanced dumbbell-shaped major tumor in preoperative MRI findings.