Carcinomatous meningitis
Carcinomatous meningitis, also referred to as meningeal carcinomatosis or neoplastic meningitis, is a serious condition characterized by the infiltration of cancer cells into the membranes surrounding the brain and spinal cord. This often occurs in late-stage cancer and can arise from various primary sources, including lung, breast, and melanoma cancers. The cancer spreads to the central nervous system via the blood and typically affects the leptomeninges, which comprise the pia mater and the arachnoid membrane, utilizing the subarachnoid space filled with cerebrospinal fluid (CSF) for dissemination.
The incidence of carcinomatous meningitis is estimated at 3-5% among cancer patients, with symptoms commonly including headaches, back pain, and neurological deficits. Diagnosis is typically achieved through imaging techniques such as MRI and analysis of CSF obtained via lumbar puncture, although negative results can occur in a significant number of cases. Unfortunately, there is currently no cure for this condition, and treatment primarily focuses on symptom management, using methods like chemotherapy delivered into the spinal fluid or radiation therapy. While some patients may respond to treatment, the overall prognosis is generally poor, with median survival extending to only a few months.
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Subject Terms
Carcinomatous meningitis
ALSO KNOWN AS: Meningeal carcinomatosis, leptomeningeal carcinomatosis, leptomeningeal metastasis, neoplastic meningitis, meningeal metastasis
RELATED CONDITIONS: Almost any type of cancer can be associated with this condition, but it is generally seen with melanoma and breast and lung cancers.
DEFINITION: Carcinomatous meningitis is the spread or infiltration of tumor cells from a primary central nervous system (CNS) source, such as a brain tumor, or from a distant or secondary source, such as a lung or breast tumor. The cancer is transmitted to membranes that envelop the brain and spinal cord. This typicall happens in late-stage cancer. This transmission occurs via the blood to the subarachnoid space, where it spreads through the fluid covering the brain, called the cerebral spinal fluid (CSF). This involves the coverings of the brain, known as the leptomeninges. The leptomeninges are further subdivided into the pia mater and the arachnoid. The area between the two is called the subarachnoid space, which acts as the conduit for the spread of tumor cells, containing the CSF fluid.
Risk factors: In adults, primary brain tumors such as oligodendroglioma or secondary tumors, also called metastases, from lung, breast, melanoma, lymphoma, ovarian, or gastric cancer can spread to the brain surfaces. In children, primary brain tumors such as ependymoma, pineal tumors, meduloblastoma, germinoma, or glioblastoma can spread to the leptomeninges.
Etiology and the disease process: The leptomeninges are the coverings of the brain. The leptomeninges can be further subdivided into the pia mater, a thin translucent sheet or membrane that adheres to the surfaces of the brain and spinal cord. This also includes the arachnoid, a delicate weblike membrane between the dura and pia mater. The area between the two is called the subarachnoid space and is filled with fluid called cerebral spinal fluid, which nourishes the brain and cushions it.
When tumor cells invade the subarachnoid space between the pia mater and the arachnoid, that invasion is called carcinomatous meningitis. Unlike other forms of meningitis, where the invading organism is a bacteria, fungus, or virus, the invaders in carcinomatous meningitis are cancer cells, and therefore it is not an infection.
Tumor growth in carcinomatous meningitis is along the CSF and can involve the dura, pia-arachnoid, or rarely the spinal cord itself. In adults, tumor growth usually results from spread of a primary brain tumor (a cancer that starts in the brain) such as oligodendroglioma or of secondary cancers from lymphoma, melanoma, or lung, breast, or gastric tumors. Secondary cancer occurs when cancer cells leave the primary site (usually the breast in carcinomatous meningitis) and spread to another organ or different parts of the body (metastasize). These secondary cancer cells can stay inactive for many years, so even when a cancer appears to have been successfully treated, it can recur. No one knows what triggers the cancer cells to become active again. It is estimated that between three and five out of every 100 patients with cancer will develop carcinomatous meningitis, and it can occur with any cancer but most commonly occurs in breast cancer.
Incidence: The incidence of carcinomatous meningitis is increasing because cancer patients are surviving longer. It is seen in about three to five percent of patients who have cancer.
Symptoms: Patients usually complain of nonspecific symptoms such as headache or back pain or focal neurologic deficits such as weakness in an extremity.
Screening and diagnosis: Carcinomatous meningitis can be diagnosed by magnetic resonance imaging (MRI) or myelography together with computed tomography (CT). A cerebral spinal fluid (CSF) or spinal tap (also called a lumbar puncture), whereby a needle is inserted into the spinal fluid within the subarachnoid space and the CSF fluid is sampled, is the usual form of diagnosis, although CSF cytology is negative in ten percent of cases. On noncontrast CT, there is obliteration of basal cisterns or sulci with hydrocephalus as an indirect sign. Contrast-enhanced MRI is more sensitive than CT and typically shows enhancement of the basilar cisterns or sulci with focal subarachnoid masses less common. It should be noted that up to thirry percent of confirmed cases of meningeal metastases will have a negative MRI.
Treatment and therapy: This disease is not curable, and the treatment aim is usually to ameliorate symptoms, usually by chemotherapy injected into the spinal fluid via lumbar puncture (intrathecal methotrexate) or by radiotherapy to the brain. Erlotinib, a drug used to treat non-small-cell lung cancer, has also been found to increase survival time in patients with carcinomatous meningitis in some cases. Other measures are to reduce pressure from cerebrospinal fluid through a spinal tap, medication, or a shunt. Radiation therapy can also be employed to eliminate cancer cells which spread to the meninges.
Prognosis, prevention, and outcomes: Some patients respond to treatment; however, the prognosis is generally poor, with death occurring within one month if the disease is untreated. Treatment can extend median survival to three to six months. New treatment options involving new chemotherapy regimens are being tested.
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