Anti-cyclic citrullinated peptide antibodies, other common autoantibodies, and smoking as risk factors for lymphoma in patients with rheumatoid arthritis.

OBJECTIVES: Patients with rheumatoid arthritis (RA) are at increased risk of lymphoma. There is no biomarker to indicate future lymphoma risk in RA and it is not known whether factors associated with an increased risk of RA also confer an increased risk of lymphoma. We investigated whether anti-cyclic citrullinated peptide (CCP) antibodies, other autoantibodies, and smoking, are associated with lymphoma development in RA. METHOD: From two population-based case-control studies, the Scandinavian Lymphoma Etiology (SCALE) study and the Epidemiological Investigation of Rheumatoid Arthritis (EIRA) I study, we identified lymphoma cases with a validated RA diagnosis (n = 50), to whom we matched study participants with RA but no lymphoma (n = 261), lymphoma but no RA (n = 257), and neither RA nor lymphoma (n = 233). Lymphomas were classified according to the WHO classification. Blood samples were analysed for immunoglobulin G (IgG), IgM, and IgA isotypes and IgG1-4 subclasses of anti-CCP antibodies and for 15 antinuclear antibody (ANA)-associated specific autoantibodies. Relative risks were estimated as crude and adjusted odds ratios (adjOR) with 95% confidence intervals (CIs) using logistic regression. RESULTS: We found no association between anti-CCP IgG ≥ 25 units/mL (adjOR 1.4, 95% CI 0.7-2.7), anti-CCP IgG ≥ 500 units/mL (adjOR 1.4, 95% CI 0.7-3.0), anti-CCP Ig of other isotypes, other autoantibodies (adjOR any vs none 0.6, 95% CI 0.3-1.2), or cigarette smoking (adjOR ever vs never 1.1, 95% CI 0.5-2.2) and lymphoma risk among patients with RA. CONCLUSION: In this study, neither anti-CCP antibodies (IgG, IgG1-4, IgM, or IgA), nor other common autoantibodies, nor smoking predicted lymphoma risk in RA.

Intravascular lymphoma: magnetic resonance imaging correlates of disease dynamics within the central nervous system.

BACKGROUND: Intravascular lymphoma (IVL) is a rare non-Hodgkin's lymphoma with relative predilection for the central nervous system. In the absence of extraneural manifestations, the disease is not recognised until autopsy in the majority of cases underlining the need for new clinical markers. METHODS: This is a retrospective series of five patients with IVL seen at a single institution over three years. An advanced magnetic resonance imaging (MRI) protocol was performed at various time points prior to diagnosis and during treatment. RESULTS: MRI revealed multiple lesions scattered throughout the cerebral hemispheres; the brainstem, cerebellum, and spinal cord were less frequently involved. On initial presentation, hyperintense lesions were seen on diffusion weighted images suggestive of ischaemia in three of four patients in whom the images were obtained at that time point. In four patients lesions were also identifiable as hyperintense areas on fluid attenuated inversion recovery (FLAIR) sequences. Initial contrast enhancement was encountered in three cases. Diffusion weighted imaging lesions either vanished or followed the typical pattern of an ischaemic small vessel stroke with evolution of abnormal FLAIR signal followed by enhancement with gadolinium in the subacute stage and tissue loss in the chronic stage. Diffusion weighted imaging and FLAIR abnormalities proved to be partially reversible, correlating with the response to chemotherapy. CONCLUSION: We provide the first detailed description of the dynamic pattern of diffusion weighted MRI in IVL. These patterns in combination with systemic findings may facilitate early diagnosis and serve as a new tool to monitor treatment response.

Development of a novel non-human primate model for preclinical gene vector safety studies. Determining the effects of intracerebral HSV-1 inoculation in the common marmoset: a comparative study.

The owl monkey (Aotus trivirgatus) has served as the standard non-human primate model of herpes simplex virus-1 (HSV-1) infection because it is highly susceptible to HSV-1 encephalitis. Owl monkeys, however, are expensive, difficult to obtain, and difficult to maintain in captivity, thus greatly hampering the efficiency of preclinical gene therapy trials for brain tumors using HSV-1-based vectors. We have therefore compared the susceptibility of the common marmoset (Callithrix jacchus) with the owl monkey in a model of intracerebral inoculation of wildtype HSV-1 F-strain at increasing titers. The common marmosets consistently succumbed earlier to viral encephalitis than the owl monkeys. The histological evaluation of the common marmoset revealed extensive HSV-1 infection with a concomitant yet less marked inflammatory response compared to the owl monkeys. PCR for HSV-1 demonstrated a similar extra-CNS shedding route in both experimental models. Our findings show that the common marmoset is at least as susceptible to intracerebral HSV-infection as the owl monkey and that it can therefore serve as a valid and reliable experimental model for the important preclinical safety tests of HSV-based therapeutic viral vector constructs in the brain.

Clinical relevance of consolidation radiotherapy and other main therapeutic issues in primary central nervous system lymphomas treated with upfront high-dose methotrexate.

PURPOSE: To evaluate the optimal dose of methotrexate (MTX) and the efficacy of other drugs, intrathecal chemotherapy (CHT), and radiotherapy (RT) in primary brain lymphomas. METHODS AND MATERIALS: Two hundred eighty-eight immunocompetent patients with histologically documented, previously untreated primary brain lymphomas, receiving CHT containing high-dose MTX (> or =1 g/m(2)) with or without RT were selected from 19 prospective series. The impact on survival of the MTX dose (<3 g/m(2) vs.> or =3 g/m(2)), the main drugs, intrathecal CHT, and combination CHT (mono-CHT vs. poly-CHT) was assessed, according to the intention-to-treat principle. The role of post-CHT irradiation (immediate vs. delayed RT) was evaluated in 119 patients with a complete response to CHT. The whole brain and tumor bed dose (<40 Gy vs. > or =40 Gy) was assessed in 70 irradiated complete responders. RESULTS: No difference in overall survival (OS) was detected between mono-CHT and combination CHT (p = 0.38). MTX > or =3 g/m(2) (p = 0.04), thiotepa (p = 0.03), and intrathecal CHT (p = 0.03) improved the OS, and nitrosoureas (p = 0.01) correlated with a worse survival. In multivariate analysis, limited to patients receiving MTX > or =3 g/m(2), only the addition of cytarabine improved the OS; nitrosoureas reduced MTX efficacy. Of the 119 complete responders, 70 received immediate RT. A RT dose of > or =40 Gy to the whole brain or tumor bed did not improve OS. The 3-year OS was similar between the immediate and delayed RT groups. In multivariate analysis, RT delay had no negative impact on survival. CONCLUSIONS: MTX > or =3 g/m(2) seems to improve survival in primary brain lymphoma patients. The efficacy of additional drugs, except for cytarabine, remains unproved. Randomized trials are needed to confirm that RT withdrawal yields no detrimental effect in complete responders.

Dose-escalation with proton/photon irradiation for Daumas-Duport lower-grade glioma: results of an institutional phase I/II trial.

PURPOSE: The role of dose escalation with proton/photon radiotherapy in lower-grade gliomas was assessed in a prospective Phase I/II trial. We report the results in terms of local control, toxicity, and survival. MATERIALS AND METHODS: Twenty patients with Grade 2/4 (n = 7) and Grade 3/4 (n = 13) gliomas according to the Daumas-Duport classification were treated on a prospective institutional protocol at Massachusetts General Hospital/Harvard Cyclotron Laboratory between 1993 and 1996. Doses prescribed to the target volumes were 68.2 cobalt Gray equivalent (CGE, 1 proton Gray = 1.1 CGE) to gross tumor in Grade 2 lesions and 79.7 CGE in Grade 3 lesions. Fractionation was conventional, with 1.8 to 1.92 CGE once per day. Eligibility criteria included age between 18 and 70 years, biopsy-proven Daumas-Duport Grade 2/4 or 3/4 malignant glioma, Karnofsky performance score of 70 or greater, and supratentorial tumor. Median age of the patient population at diagnosis was 35.9 years (range 19-49). Ten tumors were mixed gliomas, one an oligodendroglioma. RESULTS: Five patients underwent biopsy, 12 a subtotal resection, and 3 a gross total resection. Median interval from surgery to first radiation treatment was 2.9 months. Actuarial 5-year survival rate for Grade 2 lesions was 71% as calculated from diagnosis (median survival not yet reached); actuarial 5-year survival for Grade 3 lesions was 23% (median 29 months). Median follow-up is 61 months and 55 months for 4 patients alive with Grade 2 and 3 patients alive with Grade 3 lesions, respectively. Three patients with Grade 2 lesions died from tumor recurrence, whereas 2 of the 4 survivors have evidence of radiation necrosis. Eight of 10 patients who have died with Grade 3 lesions died from tumor recurrence, 1 from pulmonary embolus, and 1 most likely from radiation necrosis. One of 3 survivors in this group has evidence of radiation necrosis. CONCLUSION: Tumor recurrence was neither prevented nor noticeably delayed in our patients relative to published series on photon irradiation. Dose escalation using this fractionation scheme and total dose delivered failed to improve outcome for patients with Grade 2 and 3 gliomas.

Intraneoplastic polymer-based delivery of cyclophosphamide for intratumoral bioconversion by a replicating oncolytic viral vector.

rRp450 is an oncolytic herpesvirus that expresses the CYP2B1 cDNA, responsible for bioconverting cyclophosphamide (CPA) into the active metabolites 4-hydroxyCPA/aldophosphamide (AP). However, formal proof of prodrug activation is lacking. We report that activation of CPA in cells infected with rRp450 generates a time-dependent increase of diffusible 4-hydroxyCPA/AP. For in vivo applications, a CPA-impregnated polymer was implanted into human tumor xenografts inoculated with rRp450. The area under the curve for 4-hydroxyCPA/AP was 806 microg/g of tumor tissue/h when CPA was administered via intraneoplastic polymer and 3 microg/g of tumor tissue/h when CPA was administered i.p. Therefore, (a) a lytic virus expressing a "suicide" gene can activate a prodrug; and (b) within rRp450-infected tumor, more prolonged and higher concentrations of activated metabolites are generated by intraneoplastic compared with systemic administration of prodrug.

White-matter abnormalities in unirradiated patients cured of primary central nervous system lymphoma.

On MRI, primary brain tumors are commonly seen as contrast-enhancing masses surrounded by areas of abnormal signal on T2-weighted images. Following successful treatment tumors may no longer show contrast enhancement. The residual abnormalities are assumed to be represent "edema" and infiltrating tumor cells. We report nine patients with primary lymphoma of the central nervous system who had complete responses to intravenous methotrexate, but did not receive intrathecal chemotherapy or cranial irradiation. After complete resolution of contrast-enhancing lesions, persistent abnormalities on T2-weighted images in the region of prior tumor were initially assumed to reflect residual viable tumor. As they remained unchanged for years, however, this may not hold true in the cases in which primary central nervous system lymphoma responds to chemotherapy alone.

High microvascular blood volume is associated with high glucose uptake and tumor angiogenesis in human gliomas.

The purpose of this investigation was to elucidate the association between microvascular blood volume and glucose uptake and to link these measures with tumor angiogenesis. We demonstrate a regionally specific correlation between tumor relative microvascular blood volume (CBV), determined in vivo with functional magnetic resonance imaging techniques, and tumor glucose uptake determined with fluorodeoxyglucose positron emission tomography. Regions of maximum glucose uptake were well matched with maximum CBV across all patients (n = 21; r = 0.572; P = 0.023). High-grade gliomas showed significantly elevated CBV and glucose uptake compared with low-grade gliomas, (P = 0.009 and 0.008, respectively). Correlations between CBV and glucose uptake were then determined on a voxel-by-voxel basis within each patient's glioma. Correlation indices varied widely, but in 16 of 21 cases of human glioma, CBV and glucose uptake were correlated (r > 0.150). These measures were well correlated in all cases when comparing healthy brain tissue in these same patients. Tumor vascularity, as determined immunohistochemically and morphometrically on clinical samples, revealed statistically significant relationships with functional imaging characteristics in vivo. Regional heterogeneities in glucose uptake were well matched with functional magnetic resonance imaging CBV maps. Our findings support the concept that there is an association of microvascular density and tumor energy metabolism in most human gliomas. In addition, the findings are likely to have important clinical applications in the initial evaluation, treatment, and longitudinal monitoring of patients with malignant gliomas.

Thymidine kinase activation of ganciclovir in recurrent malignant gliomas: a gene-marking and neuropathological study.

OBJECT: The gene therapy paradigm of intratumoral activation of ganciclovir (GCV) following transduction of tumor cells by retroviral vectors bearing the thymidine kinase (tk) gene has produced dramatic remissions of malignant gliomas in animal models. In human trials, although the technique has been deemed safe, little antitumor effect has been demonstrated. To evaluate the basis of this inefficacy in human gliomas, the authors conducted a gene-marking trial involving neuropathological and biochemical studies of treated tumor specimens. METHODS: Five patients with malignant recurrent gliomas underwent stereotactic biopsy sampling and intratumoral implantation procedures with three aliquots of 10(6) vector-producing cells (VPCs) in columns. After 5 days, the tumor was resected and the tumor bed reimplanted with VPCs, and a course of GCV was given. Patients received clinical and radiological follow up for 6 months. Tumor specimens were analyzed neuropathologically and for tk gene expression by anti-TK immunohistochemistry and TK enzymatic activity. Four patients tolerated the treatment well but experienced tumor progression. The other developed an abscess after the second operation and died. Increased TK enzymatic activity was demonstrated in the one tumor specimen analyzed. Immunohistochemical evidence of tk gene expression was limited to VPCs. Transduction of tumor cells was not seen. Viable tumor cells were seen near VPCs containing TK. The lymphocytic immune response was mild. CONCLUSIONS: Except for the risk of infection inherent in reoperation, this tk-GCV paradigm was both feasible and safe. Pathological studies indicated that limited dissemination of VPCs and vector from the infusion site and failure to transduce tumor cells with the tk gene are major barriers to efficacy.

Complement depletion facilitates the infection of multiple brain tumors by an intravascular, replication-conditional herpes simplex virus mutant.

Intravascular routes of administration can provide a means to target gene- and virus-based therapies to multiple tumor foci located within an organ, such as the brain. However, we demonstrate here that rodent plasma inhibits cell transduction by replication-conditional (oncolytic) herpes simplex viruses (HSV), replication-defective HSV, and adenovirus vectors. In vitro depletion of complement with mild heat treatment or in vivo depletion by treatment of athymic rats with cobra venom factor (CVF) partially reverses this effect. Without CVF, inhibition of cell infection by HSV is observed at plasma dilution as high as 1:32, while plasma from CVF-treated animals displays anti-HSV activity at lower dilutions (1:8). When applied to the therapy of intracerebral brain tumors, in vivo complement depletion facilitates the initial infection (assayed at the 2-day time point) by an intra-arterial replication-conditional HSV of tumor cells, located within three separate and distinct human glioma masses. However, at the 4-day time point, no propagation of HSV from initially infected tumor cells could be observed. Previously, we have shown that the immunosuppressive agent, cyclophosphamide (CPA), facilitates the in vivo propagation of an oncolytic HSV, delivered intravascularly, within infected multiple intracerebral masses, by inhibition of both innate and elicited anti-HSV neutralizing antibody response (K. Ikeda et al., Nat. Med. 5:881-889, 1999). In this study, we thus show that the addition of CPA to the CVF treatment results in a significant increase in viral propagation within infected tumors, measured at the 4-day time period. The concerted action of CVF and CPA significantly increases the life span of athymic rodents harboring three separate and large glioma xenografts after treatment with intravascular, oncolytic HSV. Southern analysis of viral genomes analyzed by PCR reveals the presence of the oncolytic virus in the brains, livers, spleens, kidneys, and intestine of treated animals, although none of these tissues displays evidence of HSV-mediated gene expression. In light of clinical trials of oncolytic HSV for malignant brain tumors, these findings suggest that antitumor efficacy may be limited by the host innate and elicited humoral responses.

Multicolumn infusion of gene therapy cells into human brain tumors: technical report.

OBJECTIVE: Effective gene therapy for brain tumors may require saturation of the tumors with tumoricidal doses of the therapeutic gene. Safe, precise, and efficient delivery of gene therapy vectors is required. Most reported cases of and published protocols for gene therapy for brain tumors involve freehand injection of retroviral vector-producing cells (VPCs) into the brain. Major disadvantages of this method include the inaccuracy of hand-guided needle placement and limited control of injection parameters. These factors can result in failure to deliver the viral vectors to specifically targeted sites within the brain, extensive tissue disruption resulting from excessively forceful injection, and reflux of the injectate along the needle tract. METHODS: We describe a novel stereotactic strategy for saturating tumor volumes with tumoricidal doses of gene therapy vectors and a new, more precise method of infusing VPCs. With our new instrument, the multicolumn stereotactic infusion system, needle placement is stereotactically guided and both VPC infusion and needle withdrawal are mechanically controlled. RESULTS: This technique, which has been used effectively for six patients, permits precise deposition of columns of VPCs throughout the targeted tumor volume. CONCLUSION: This technique should facilitate saturation of tumors with tumoricidal doses of gene therapy vectors and should improve the results of gene therapy protocols that rely on intraparenchymal injection for delivery.

Intravenous methotrexate as initial treatment for primary central nervous system lymphoma: response to therapy and quality of life of patients.

In anticipation of a consortium study of methotrexate (MTX) therapy provided to patients with primary central nervous system lymphoma (PCNSL) we have provided intravenous MTX without irradiation therapy to 31 nonimmunosuppressed individuals. Twenty (65%) achieved complete response and 11 (35%) partial response to therapy. For the 31 patients the median survival was 30.43 months with an actuarial median follow-up time of 30.69 months. The 2+ year survival was 63% for all patients and 90% for complete responders. Of 375 drug cycles, grade 3 leukopenia was identified in 3 cycles, mucositis in 6 cycles and delayed drug clearance in 47 cycles. Recurrences included brain (9/20) and/or spinal fluid (2/20). The median Karnofsky scale improved from 40 (10-80) prior to therapy to 90 after treatment. Eleven patients, in complete response for a median of 22+ months after diagnosis were evaluated using 4 instruments that assess Quality of Life Functional Assessment of Cancer Therapy - Brain (FACT-BR) modified, Symptom Questionnaire, Social Adjustment Scale-Self-Report and Problem Solving Inventory. Their psychosocial adjustment, well-being and stress coping abilities were comparable to the normative groups. Further there was no evidence of any MTX-induced, Magnetic Resonance Imaging (MRI)-detected encephalopathy in these individuals and there was preservation of clinical cognition and memory. We conclude that therapy with MTX, without radiation can be used in PCNSL patients without limitations of age or pretreatment Karnofsky scores. Further rates of response and median survival approach those of therapies using multiple drugs and radiation, but with a less likely risk of dementia.

Intraocular-central nervous system lymphoma: clinical features, diagnosis, and outcomes.

OBJECTIVE: To analyze the clinical features, laboratory investigations, and diagnosis of intraocular-central nervous system (CNS) lymphoma in a cohort of patients who underwent diagnostic vitrectomy. DESIGN: Retrospective case series. METHOD AND STUDY MATERIALS: Thirty-four vitreous biopsy specimens obtained from 26 patients with treatment-resistant or unusual uveitis were re-evaluated in a masked fashion. The specimens were classified into three groups: "negative," "suspicious of malignancy," and "positive" based on the cytologic features, immunomarkers, and flow cytometry. The medical records of the patients were reviewed retrospectively. MAIN OUTCOME MEASURES: The reliability of vitreous cytology in diagnosing intraocular-CNS lymphoma and the differences in clinical features of patients with intraocular-CNS lymphoma and uveitis. RESULTS: The two ocular pathologists concurred in their criteria for interpretation of all specimens. There was 100% concordance between the cytologic reports read independently by the two ocular pathologists over the 5-year period and the read-out done in a masked fashion at the time of the study. Ten patients were diagnosed with intraocular-CNS lymphoma based on the vitreous cytology and clinical features. The time interval between the initial presentation and vitreous biopsy was 1 week to 2 years, with 80% of the patients diagnosed within the first year. Retinal involvement in the form of lymphomatous subretinal pigment epithelial infiltrates, vasculitis, and apparent retinochoroiditis was present in six cases. Initial neuroimaging studies revealed concomitant CNS involvement in three patients, and an additional three developed CNS lymphoma following diagnosis by vitreous biopsy. Patients were treated with radiotherapy, chemotherapy, or both. Two of the four patients with a follow-up of greater than 12 months died due to CNS involvement. CONCLUSIONS: Vitreous cytology is a sensitive, reliable, and reproducible method of diagnosing intraocular-CNS lymphoma. A high index of suspicion based on the clinical findings and course of the uveitis is critically important in decision-making for diagnostic vitrectomy. Central nervous system involvement is frequent and associated with a high mortality rate. Ophthalmology 1999;106:1805-1810

Accelerated fractionated proton/photon irradiation to 90 cobalt gray equivalent for glioblastoma multiforme: results of a phase II prospective trial.

OBJECT: After conventional doses of 55 to 65 Gy of fractionated irradiation, glioblastoma multiforme (GBM) usually recurs at its original location. This institutional phase II study was designed to assess whether dose escalation to 90 cobalt gray equivalent (CGE) with conformal protons and photons in accelerated fractionation would improve local tumor control and patient survival. METHODS: Twenty-three patients were enrolled in this study. Eligibility criteria included age between 18 and 70 years, Karnofsky Performance Scale score of greater than or equal to 70, residual tumor volume of less than 60 ml, and a supratentorial, unilateral tumor. Actuarial survival rates at 2 and 3 years were 34% and 18%, respectively. The median survival time was 20 months, with four patients alive 22 to 60 months postdiagnosis. Analysis by Radiation Therapy Oncology Group prognostic criteria or Medical Research Council indices showed a 5- to 11-month increase in median survival time over those of comparable conventionally treated patients. All patients developed new areas of gadolinium enhancement during the follow-up period. Histological examination of tissues obtained at biopsy, resection, or autopsy was conducted in 15 of 23 patients. Radiation necrosis only was demonstrated in seven patients, and their survival was significantly longer than that of patients with recurrent tumor (p = 0.01). Tumor regrowth occurred most commonly in areas that received doses of 60 to 70 CGE or less; recurrent tumor was found in only one case in the 90-CGE volume. CONCLUSIONS: A dose of 90 CGE in accelerated fractionation prevented central recurrence in almost all cases. The median survival time was extended to 20 months, likely as a result of central control. Tumors will usually recur in areas immediately peripheral to this 90-CGE volume, but attempts to extend local control by enlarging the central volume are likely to be limited by difficulties with radiation necrosis.

Oncolytic virus therapy of multiple tumors in the brain requires suppression of innate and elicited antiviral responses.

The occurrence of multiple tumors in an organ heralds a rapidly fatal course. Although intravascular administration may deliver oncolytic viruses/vectors to each of these tumors, its efficiency is impeded by an antiviral activity present in complement-depleted plasma of rodents and humans. Here, this activity was shown to interact with complement in a calcium-dependent fashion, and antibody neutralization studies indicated preimmune IgM has a contributing role. Short-term exposure to cyclophosphamide (CPA) partially suppressed this activity in rodents and humans. At longer time points, cyclophosphamide also abrogated neutralizing antibody responses. Cyclophosphamide treatment of rats with large single or multiple intracerebral tumors substantially increased viral survival and propagation, leading to neoplastic regression.

A review of the therapy of paraneoplastic neurologic syndromes.

The therapy of paraneoplastic neurologic syndromes remains unclear and warrants a systematic review of the literature. Reports in English and foreign language literature were abstracted. Data were sorted by the primary paraneoplastic neurologic syndrome, the primary malignancy, and the methods of treatment. Neurologic improvement follows surgical, chemotherapeutic, and radiation treatments. Adjuvant immunosuppressive therapy with steroids, plasmapheresis, or immunoglobulin may help stabilize the progression of neurologic symptoms. Syndromes characterized by inflammation or neurotransmitter production without neuronal loss are most responsive to therapy. While treatment of the underlying cancer with appropriate surgery, chemotherapy, and radiation is recommended, the paraneoplastic syndrome should probably be managed with immunosuppressive therapy.

Early changes measured by magnetic resonance imaging in cerebral blood flow, blood volume, and blood-brain barrier permeability following dexamethasone treatment in patients with brain tumors.

OBJECT: In this study the authors assessed the early changes in brain tumor physiology associated with glucocorticoid administration. Glucocorticoids have a dramatic effect on symptoms in patients with brain tumors over a time scale ranging from minutes to a few hours. Previous studies have indicated that glucocorticoids may act either by decreasing cerebral blood volume (CBV) or blood-tumor barrier (BTB) permeability and thereby the degree of vasogenic edema. METHODS: Using magnetic resonance (MR) imaging, the authors examined the acute changes in CBV, cerebral blood flow (CBF), and BTB permeability to gadolinium-diethylenetriamine pentaacetic acid after administration of dexamethasone in six patients with brain tumors. In patients with acute decreases in BTB permeability after dexamethasone administration, changes in the degree of edema were assessed using the apparent diffusion coefficient of water. CONCLUSIONS: Dexamethasone was found to cause a dramatic decrease in BTB permeability and regional CBV but no significant changes in CBF or the degree of edema. The authors found that MR imaging provides a powerful tool for investigating the pathophysiological changes associated with the clinical effects of glucocorticoids.

Case report of unusual leukoencephalopathy preceding primary CNS lymphoma.

A previously healthy 35 year old woman presented with bilateral uveitis associated with multiple, evolving, non-enhancing white matter lesions consistent with a progressive leukoencephalopathy such as multiple sclerosis. Thirty months after her initial presentation, she was diagnosed with primary CNS lymphoma and died 14 months later. The unusual clinical course preceding the diagnosis suggests that a demyelinating disease may have preceded, and possibly heralded, the development of primary CNS lymphoma. Cases of "sentinel lesions" heralding the diagnosis of primary CNS lymphoma have been reported, and this case further corroborates such instances and raises further issues regarding possible neoplastic transformation occurring in inflammatory diseases such as multiple sclerosis.