Leptomeningeal metastasis from central nervous system tumors： A study of classification and stage in the spinal canal of 58 patients

Leptomeningeal metastasis (LM) is caused by the spread of malignant tumor cells into the subarachnoid space. However, classification and staging of LM in the spinal canal is rare in the literature. The authors reviewed the records of 58 Chinese patients with LM for clinical features, neuroimaging, and treatments. Gadolinium-enhanced magnetic resonance imaging (MRI) of brain and spinal cord were performed in all patients. Removal of intracranial tumors was performed in all patients and diagnoses were confirmed by histology. The study group consisted of 58 patients, with 29 cases presenting with intraspinal symptoms. Of the 58, 8 patients underwent intraspinal tumor removal, 8 received radiotherapy alone, 9 received chemotherapy alone, and 34 patients received combined radiochemotherapy. We classified LM into 3 types: type L or leptomeninges LM, is subdivided into 2 subtypes (subtype LI and LII (a,b)), type N or nerve root LM is subdivided into 2 subtypes (subtype NI and NII (a,b)), and type M or mixed-type LM. We also divided LM into stages of I-IV according to the symptoms and the volume of the tumor based on spinal axial MRI. Type LI LM often occurs in patients with intracranial and intraspinal tumors found simultaneously. Patients who receive surgery for intracranial tumors may present with type N LM. Surgery is suitable for patients with NI LM and LIIb LM in stages III–IV, presenting with severe spinal symptoms. The prognosis is better for type N LM than type L LM.