Development of stroma in malignant lymphomas of the brain compared with epidural lymphomas. An immunohistochemical study

Primary central nervous system lymphoma

Primary central nervous system lymphomas (PCNSL) are uncommon neoplasms accounting for less than 2% of brain tumours. Their incidence appears to be increasing across a wide age range, in both immunocompetent and immunosuppressed populations. Particular risk groups include those with congenital and acquired immunodeficiencies and transplant recipients. The spread of the AIDS epidemic has seen large numbers of complicating PCNSL develop. Epstein-Barr virus infection appears to play a role in the development of these lymphomas in the immunosuppressed population. The aetiology of these tumours in the immunocompetent is uncertain. Their tendency to remain within the nervous system is not well understood but may be a function of CNS binding molecules carried by lymphocytes. Clinically PCNSL may present with a wide variety of signs and symptoms and has a capacity to mimic many other neurological conditions. Radiologically they appear as hyperdense homogenous deposits in subcortical white matter. Although most lesions are intermediate or high grade B cell lymphomas, T cell lymphomas are being recognised with increasing frequency. Immunohistochemistry and genotypic analysis have an important role in accurately characterising PCNSL, particularly in stereotactic biopsies. Involvement of multiple areas of the neuraxis, the eye and multiple intracranial sites can occur in the absence of obvious systemic lymphoma. The role of surgery in their treatment is uncertain. A combination of radiotherapy and chemotherapy can increase the length of survival. The prognosis, however, remains poor in comparison with nodal lymphomas, and particularly so in those with AIDS.

Primary central nervous system lymphomas--an update

Primary CNS lymphomas (PCNSL), until recently representing about 1% of all brain tumors, show dramatically increased incidence both in high-risk groups (immunocompromised, AIDS) and in the general population. They are extranodal diffuse non-Hodgkin's lymphomas, the morphology and classification of which are identical to those of systemic lymphomas, although PCNSL show different biological behavior and diagnosis according to the New Working Formulation and updated Kiel classification may be difficult. The majority are large B cell variants of high-grade malignancy; low-grade subtypes and T cell lymphomas are rare. Sixty per cent occur in the supratentorial space (hemispheres, periventricular) and 12% in the posterior fossa; 30% are multiple (50%-70% in AIDS). PCNSL show a male preponderance with a peak incidence in the 5th-7th decade (3rd-4th in AIDS). The duration of diffuse or focal clinical symptoms averages 1-2 months. Computed tomography and magnetic resonance imaging scans show single or multiple or diffuse, often typical lesions. Diagnosis is achieved by evaluation of stereotactic biopsy material or cerebrospinal fluid cytology using immunocytological markers. Current therapy in immunocompetent patients, radiation plus corticosteroids and pre- or postradiation polychemotherapy, shows response rates of 85% with a median survival of 17-44 months, a prognosis similar to that for glioblastoma. Meningeal PCNSL is treated with intrathecal methotrexate or cytosine arabinoside. Transliquoral seeding of PCNSL is frequent, distant metastases occurring in 6%-8%. Therapy of AIDS-related PCNSL makes use of radiation and corticosteroids, and rarely of chemotherapy. The pathogenesis of PCNSL is unknown, but Epstein-Barr virus may be a contributory factor.

Non-Hodgkin lymphomas of the central nervous system

Non-Hodgkin lymphomas (NHL) of the Central Nervous System (CNS) are rare but they nonetheless constitute a clinical, biological and therapeutic problem of great interest. Primary lymphomas of the CNS account for 2% of all malignant lymphomas and for 0.3-1.5% of all intracranial tumors. Surgery and radiotherapy afford only poor control of the disease. The most satisfactory results have been achieved with combination therapy, surgery + radiotherapy + chemotherapy, but the optimal combination has still to be devised. Secondary neuromeningeal involvement affects a fair number of patients with systemic NHL. The symptoms are broadly the same as in CNS NHL and the treatment as problematic. There have recently been suggestions that the onset of CNS NHL may be exacerbated by immunodeficiency states such as occur in patients who have undergone organ transplantation, in autoimmune disease and, still more recently, in the acquired immunodeficiency syndrome (AIDS). The frequency of these tumors is anyway on the increase and a better insight into the disease in essential.

Lectin histochemistry of human gliomas

Formalin-fixed and paraffin-embedded specimens of 24 human gliomas were examined histochemically with five lectins; concanavalin A (Con A), wheat germ agglutinin (WGA), Ricinus communis agglutinin 1 (RCA-1), peanut agglutinin (PNA), and Ulex europaeus agglutinin 1 (UEA-1). Although the staining intensity with lectins was variable, tumor cells in five astrocytomas, three oligodendrogliomas, six ependymomas, and one gliosarcoma, were generally positive for Con A, WGA, and RCA-1, and negative for PNA and UEA-1, whereas those in nine glioblastomas were usually positive for Con A and WGA and negative for RCA-1 and PNA as well as UEA-1. The malignancy in neoplastic astrocytes was correlated with the decrease in binding with lectins, especially RCA-1. Blood vessels, particularly the endothelial layers, in all gliomas were stained intensely with all lectins used. Macrophages showed two staining features with lectins; stippled and granular. The former macrophages were positive for Con A, WGA, RCA-1, and PNA, and negative for UEA-1, whereas the latter macrophages were positive for all lectins used. Thus, the staining characteristics with lectins of macrophages were different from those of any glioma cells and very useful for identification of macrophages in gliomas.

Contribution of histiocytic cells to sarcomatous development of the gliosarcoma. An immunohistochemical study

The expression of glial fibrillary acidic protein, fibronectin (FN), factor VIII-related antigen (FVIII/RAG), and of three monohistiocytic markers, lysozyme, alpha-1-antitrypsin and alpha-1-antichymotrypsin was examined in five gliosarcomas (GS) by peroxidase-antiperoxidase immunostaining of formalin-fixed and paraffin-embedded specimens, and compared with vascular changes in 16 glioblastomas (GB). In contrast to GB, endothelial proliferations of GS were sheathed by sarcomatous tissue (perivascular sarcoma), which was contiguous with fibrosarcomatous areas. Cells with conspicuous intracytoplasmic FN content (FN+ cells) were seen in the vascular stroma of GB and dominated in the sarcomatous parts of GS. Most FN+ cells of GS were of varying size and shape and clearly neoplastic. Monohistiocytic markers were demonstrable in small infiltrating mononuclear cells as well as in many sarcomatous cells including FN+ cells. FVIII/RAG was restricted to lumen-lining endothelium and was not found in sarcomatous cells. These results suggest that a major part of sarcoma in GS is less likely to develop from proliferated endothelial cells than from histiocytic cells in the perivascular spaces of GB. By FN mediation, histiocytic cells might also guide and promote sarcomatous proliferations of other mesenchymal cells, leading to fibrosarcomatous development. Prominent monstrous giant cells of one GS seemed to be degenerating glioma cells.