The appearance of non-Hodgkin lymphoma in the meninges and adjacent roots or peripheral nerves (a form of the earlier mentioned neurolymphomatosis) is distinct from primary CNS lymphoma, in which there are parenchymal lesions and no systemic disease. The clinical and CSF pictures are similar to those of meningeal leukemia and carcinomatosis described earlier. In the rare cases of meningeal involvement with Hodgkin lymphoma, there may be an eosinophilic pleocytosis. Leptomeningeal dissemination occurs almost exclusively in high-grade lymphomas with diffuse (rather than nodular) changes in the lymph nodes. Cranial nerve palsies are common, with a predilection for the eighth nerve; the cauda equina is involved eventually in most cases. The optimal treatment has not yet been ascertained. Radiotherapy and systemic and intraventricular chemotherapy have all met with some degree of success in small series.
Intravascular Lymphoma and Related Disorders (including Lymphomatoid Granulomatosis, Castleman Disease)
These conditions are presented here with other forms of lymphoma, although their clinical behavior is as much in keeping with a vasculitic or prelymphomatous process. Although considered rare, we encounter several new cases yearly in our service. The nomenclature is confusing and the original terms, lymphomatoid granulomatosis and Castleman disease are not equivalent to the more recently elucidated process of intravascular lymphoma; it is more accurate to consider the first two as prelymphomatous processes. As described by Liebow and colleagues, lymphomatoid granulomatosis is a systemic disease with prominent nodular pulmonary lesions, dermal, and lymph node changes and, in approximately 30 percent of cases, involvement of the CNS. In a small proportion, the changes are confined to the nervous system. According to Katzenstein and associates, a systemic malignant lymphoma develops in 12 percent of such patients. Castleman disease is precipitated by constituent HHV-8 virus infection in about half of cases and lymphomatoid granulomatosis has a similar viral origin, but mainly from EBV.
The intravascular lymphoma, on the other hand, is regarded as a multifocal neoplasm of large anaplastic monoclonal lymphocytes that infiltrate the walls of blood vessels and surrounding areas (Sheibani et al). The tumor cells grow intravascularly and cause occlusion of small and moderate-sized vessels and may cause small cerebral or spinal infarctions, as well as of other organs. The disease can be distinguished from primary CNS lymphoma, which is also typically “angiocentric,” meaning centered around vessels, but does not selectively invade and occlude vascular structures. In half of the cases, meningeal vessels are involved and in a few, the peripheral nerves, or more particularly the endoneurial vessels within spinal roots, have been involved by the neoplasm and we have seen two cases with a flaccid paraplegia on this basis.
The lymphoid origin of the intravascular anaplastic cells is clear, and the predominant species is of monoclonal B cells with a T-cell reactive component. As in some cases of primary CNS lymphoma, portions of the genome of EBV have occasionally been isolated from the malignant B cells. It has been proposed that the disorder in those cases represents an EBV-induced proliferation of B cells with a prominent inflammatory T-cell reaction (Guinee et al).