Leptomeningeal carcinomatosisLeptomeningeal carcinomatosis are also called neoplastic meningitis or, depending on the tumors specificity, meningeal carcinomatosis or lymphomatous meningitis. In terms of pathologic point of view, there are three types of tumor involvement: 1) a diffuse a thin layer of tumor cells on the leptomeninx, 2) nodular growth of macroscopic tumor metastases to the meninxs and nerve roots or 3) metastases in the leptomeninx level, with the extension of the tumor in the Virchow-Robin space. Leptomeninx metastases can coexist with CNS (central nervous system) parenchymal metastases.
Cancers usually metastasize to the meninx via the bloodstream. Alternatively surface localized parenchymal metastases send the cells directly in the subarachnoid space. Certain tumors, including cutaneous squamous cell carcinoma and certain non-Hodgkin lymphoma, have a predisposition to develop along the peripheral nerves and can infiltrate the meninx in this way.
Leptomeningeal clinical evidence of metastasis is present in 8% of patients with metastasic solid tumors; necropsy is present in 19 percent. Among solid tumors, adeno-carcinoma of breast and lung cancer and melanoma are most often responsible for leptomeningeal metastases. At one quarter of patients, systemic cancer is under control, so effective damage control can improve the quality and lifespan.
Leptomeningeal metastases have signs and symptoms at multiple levels of the nervous system, often within known systemic malignancies. Hydrocephalus, encephalopathy or focal neurologic deficits may be present. Involvement of cranial nerves, spinal nerve roots or spinal cord can mean compression, by developing meninx disease. Neurological signs are beyond typical symptoms that have been described by patients.
Leptomeningeal metastases are diagnosed by cytologic examination of CSF malignant cells by using MRI demonstration of this nodular tumor deposits in the meninx or diffuse meningeal infiltration or meningeal biopsy. In LCR doctors can detect elements of inflamatory meningitis consisting in lymphocytic pleocytosis, elevated protein levels, normal or low CSF glucose, and in some cases, an increase of IgG monoclonal.
A complete MRI examination of the nervous axis may show hydrocephaly caused by obstruction of CSF’s transport and identify tumor development in subarachnoid space.
Intrathecal chemotherapy and external radiotherapy to damage leptomeninx are the best options for treatment. Approximately 20% of patients treated aggressively for leptomeningeal carcinomatosis can expect a sustained positive response for 6 months. Intrathecal therapy of meningeal tumor exhibits a high concentration of chemotherapeutic agents with low systemic toxicity. Methotrexate can be administered intrathecally and is effective against leptomeningeal carcinomas. Intrathecal chemotherapy may be administered either by repeated lumbar puncture or through an internal Ommaya reservoir, consisting of a catheter attached to a lateral ventricle, attached to a reservoir fixed under the scalp.
Large tumor deposits in the meninx or along the nerve roots have a very vague answer to the intrathecal chemotherapy because of the too large diffusion barrier. So, in these cases, external radiation therapy is used. Hydrocephaly is treated ventricular-peritoneal, although behind the peritoneum tumor is possible, it is rare in practice.
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