The metastatic tumor cells grow either attached to the pia mater covering the brain and spinal cord or floating unattached to the subarachnoid space. Tumors of diverse origins and hematologic cancers may spread to this space.Some patients can develop a leptomeningeal tumor while receiving chemotherapy for their primary tumor. Pathology
There are three anatomic patterns by which the tumor can spread in the subarachnoid space. More than one pattern may coexist in the same patient.First, there may be plaque-like deposits of cells in the leptomeninges with invasion of Virchow-Robin spaces and, usually, the shedding of tumor cells into the cerebrospinal fluid.Second, there may only be a thin coating of meninges, in some cases with only a single cell layer, but also with shedding of tumor cells into the cerebrospinal fluid. Third, there may be a pattern of nodular deposits of tumor on cranial and spinal nerve roots, frequently without tumor cells being shed into the cerebrospinal fluid.The first and third patterns are common in solid tumors whereas the second occurs most frequently with leukemia and lymphoma. Spinal cord
Neoplastic meningitis (NM) shows diffuse infiltration of tumor cells into the subarachnoid space which may be associated with increased intracranial pressure, signs of meningeal irritation, and damage to the cranial and spinal nerve roots. Pathological feature include:
Circular necrosis of the white matter in the periphery of the spinal cord was also noted which probably resulted from circulatory disturbance secondary to tumor infiltration.
Diagnosis
Ganglioneuromas can be diagnosed visually by a CT scan,  MRI scan, or an ultrasound of the head, abdomen, or pelvis. Blood and urine tests may be done to determine if the tumor is secreting hormones or other circulating chemicals. A biopsy of the tumor may be required to confirm the diagnosis. Treatment
Because ganglioneuromas are benign, treatment may not be necessary, as it would expose patients to more risk than leaving it alone.If there are symptoms or major physical deformity, treatment usually consists of surgery to remove the tumor. Prognosis
Most ganglioneuromas are noncancerous, thus expected outcome is usually good. However, a ganglioneuroma may become cancerous and spread to other areas, or it may regrow after removal.If the tumor has been present for a long time and has pressed on the spinal cord or caused other symptoms, it may have caused irreversible damage that cannot be corrected with the surgical removal of the tumor. Compression of the spinal cord may result in paralysis, especially if the cause is not detected promptly. References


== External links ==