Imaging of Adult Malignant Soft Tissue Tumors of the Spinal Canal: A Guide for Spine Surgeons.

BACKGROUND: Interpretation of malignant soft tissue spinal canal tumors imaging is essential in guiding spine surgeons to establish a differential diagnosis. This task is intricate due to a great radiologic pattern overlap among entities. We present in this manuscript a step-by-step strategy that can guide spine surgeons identify a likely malignant soft tissue lesion in the spinal canal based on imaging features. In addition, we provide a review of the radiologic features of malignant soft tissue spinal canal tumors, assisting spine surgeons refining their diagnostic approach based on several essential imaging characteristics.

RESULTS: Diagnosis of soft tissue spinal canal malignancies starts with the identification of the lesion's spinal level and its relationship to the dura and medulla. The second step consists in characterizing it as likely-malignant based on radiological signs like a larger size, ill-defined margins, central necrosis, and/or increased vascularity. The third step is to identify additional imaging features such as intra-tumoral hemorrhage or cyst formation that can suggest specific malignancies. The physician can then formulate a differential diagnosis. The most encountered malignant soft tissue tumors of the spinal canal are anaplastic ependymomas, anaplastic astrocytomas, metastatic tumors, lymphoma, peripheral nerve sheath tumors, and central nervous system melanomas. A detailed review of the imaging features of every type/subtype of lesion is presented in this work. Although MRI still remains the modality of choice for spinal tumor assessment, other techniques such as dynamic contrast agent-enhanced perfusion MRI or diffusion-weighted imaging could guide diagnosis in specific situations.