Teaching Case

The patient, coming from the Oncology unit, suffered from breast cancer surgically treated two years before. At admission she showed spine pain and complete paralysis of the lower half of the body.

MR imaging examination on 1.5 T system, coil dedicated, on the axial, coronal and sagittal plans, using FSE T1W, T2W and Fat Suppression (STIR) sequences, were performed. MRI showed a large mass (isointense in the T1- and T2-weighed images) involving the cauda equina roots from L1 to L3; also showed multiple vertebral metastases with extravertebral spreading.

Leptomeningeal carcinomatosis (LC) occurs when a patient’s cancer metastasizes to the meninges surrounding the spinal cord and spreads diffusely throughout the subarachnoid space to produce multifocal neurological signs and symptoms. It is an end-stage cancer phenomenon, and a relatively rare metastasis. Among the tumours of the nervous system the one which shows greater presence of leptomeningeal metastases is medulloblastoma. Among the extra-cranial tumours the greater leptomeningeal involvement is present in leukaemias, while only in 5% of the mammary carcinomas and in 3% of the melanomas [1]. Malignant cells can metastasize to the meninges in several ways. Haematogenous spread is the most common route, but this type of entry is more often seen in haematologic malignancies like leukaemia than in solid primary cancers. Solid tumours tend to spread through lymphatics to reach the meninges, and enter the subarachnoid space by passing through the dural and arachnoid coverings of spinal and cranial nerve roots. Other pathways described include direct spread from metastases in the CNS parenchyma. No matter the route, once malignant cells gain access to the CSF, they seed the meningeal surface by CSF flow and grow to form deposits that can appear either diffusely thin, or plaque-like and forming nodules along the meninges. The cancerous cells can then invade the pial membrane to reach the spinal nerves, cranial nerves, and spinal cord, resulting in the multifocal neurologic symptoms that characterize the metastasis. A direct MRI examination, the most frequent proof is that of an obliteration or filling of the sub-arachnoid spaces, of diffused or localised type. The metastatic localization may appear like nodular foci, micro- or macro-nodular or linear along the surface of the encephalic nervous structures. They generally appear isointense or slightly hyper-intense in the T1-weighted sequences, they become hyper-intense in the T2-weighted sequences and, in this case, they are confused with hyper-intense signal of cerebrospinal fluid; they are therefore better distinguishable if sequences with suppression of signal fluid (FLAIR) are used. Statistic studies have demonstrated that the usage of contrast medium increases the sensibility of the methodical MRI in the search of very small leptomeningeal metastases [2].
Treatment of leptomeningeal carcinomatosis requires a multidisciplinary approach. The current goal of therapy is improvement or stabilization of patients’ neurologic symptoms. Therapeutic approaches include intrathecal chemotherapy (mainly with methotrexate), radiotherapy of the meninges, systemic chemotherapy with drugs that penetrate the CSF [3].