Topotecan as salvage therapy for relapsed or refractory primary central nervous system lymphoma

Treatment for patients with refractory or relapsed primary CNS lymphoma (PCNSL) remains unsatisfactory. Topotecan is an intravenous topoisomerase I inhibitor with good CSF penetration and documented efficacy in patients with relapsed systemic non-Hodgkin's lymphoma. In this study 15 patients with refractory or relapsed PCNSL were treated with intravenous topotecan (1.5 mg/m(2)) for five consecutive days during each 21-day cycle. All 15 patients had measurable, contrast-enhancing tumor on cranial MRI at the time of relapse. Three (20%) patients achieved a complete response after one, three and four cycles, respectively, while three (20%) patients achieved a partial response after two cycles each, for a total response proportion of 40%. Three patients had stable disease at the end of topotecan treatment. Six patients (40%) had progressive disease during treatment. Median overall survival was 981 days (95% CI: 275, NA) and median progression free survival was 60 days (95% CI: 46, 945). Three out of 15 patients had grade 3 thrombocytopenia. Six out of 15 patients had grade 3 neutropenia, while 5/15 patients had grade 4 neutropenia, and 13/15 patients received g-CSF at some point during treatment. There were no deaths directly related to treatment toxicity. Our study shows that topotecan, as a salvage therapy in patients with relapsed or refractory PCNSL, is associated with an overall response proportion of 40% and should be considered in patients who have failed prior methotrexate-based chemotherapy and/or whole brain irradiation. However, progression is frequent and early and most patients required growth factor support due to myelotoxicity.

Phase I and correlative biology study of cilengitide in patients with recurrent malignant glioma

PURPOSE

This multi-institutional phase I trial was designed to determine the maximum-tolerated dose (MTD) of cilengitide (EMD 121974) and to evaluate the use of perfusion magnetic resonance imaging (MRI) in patients with recurrent malignant glioma.

PATIENTS AND METHODS

Patients received cilengitide twice weekly on a continuous basis. A treatment cycle was defined as 4 weeks. Treatment-related dose-limiting toxicity (DLT) was defined as any grade 3 or 4 nonhematologic toxicity or grade 4 hematologic toxicity of any duration.

RESULTS

A total of 51 patients were enrolled in cohorts of six patients to doses of 120, 240, 360, 480, 600, 1,200, 1,800, and 2,400 mg/m2 administered as a twice weekly intravenous infusion. Three patients progressed early and were inevaluable for toxicity assessment. The DLTs observed were one thrombosis (120 mg/m2), one grade 4 joint and bone pain (480 mg/m2), one thrombocytopenia (600 mg/m2) and one anorexia, hypoglycemia, and hyponatremia (800 mg/m2). The MTD was not reached. Two patients demonstrated complete response, three patients had partial response, and four patients had stable disease. Perfusion MRI revealed a significant relationship between the change in tumor relative cerebral blood flow (rCBF) from baseline and area under the plasma concentration versus time curve after 16 weeks of therapy.

CONCLUSION

Cilengitide is well tolerated to doses of 2,400 mg/m2, durable complete and partial responses were seen in this phase I study, and clinical response appears related to rCBF changes.

Isolated optic nerve lymphoma diagnosed by optic nerve biopsy

PURPOSE

To report a case of isolated optic nerve lymphoma diagnosed by optic nerve biopsy.

DESIGN

Case report.

METHODS

A 66-year-old woman was referred to the Neuro-Ophthalmology Service because of a decrease in visual acuity and right optic disk edema.

RESULTS

A magnetic resonance image of the brain showed only enhancement of the optic nerve. An examination that included ANA, c-ANCA, p-ANCA, Lyme titers, FTA-ABS, ACE level, chest x-ray, and lumbar puncture was negative. Because of rapid progression on clinical examination and serial imaging, an optic nerve biopsy was performed, which showed B-cell lymphoma.

CONCLUSION

Optic nerve lymphoma can be confused with a variety of inflammatory and neoplastic infiltrations of the optic nerve on clinical and radiographic examinations. Optic nerve biopsy can be valuable in diagnosing isolated optic nerve lymphoma if other diagnostic tests are unrevealing, but the procedure carries considerable risk of loss of visual acuity and should be recommended judiciously.

A randomized, double-blind, placebo-controlled, phase 2 study of RMP-7 in combination with carboplatin administered intravenously for the treatment of recurrent malignant glioma

RMP-7, a bradykinin analog, temporarily increases the permeability of the blood-brain tumor barrier to chemotherapy drugs like carboplatin. We conducted a randomized, controlled trial of carboplatin and RMP-7 versus carboplatin and placebo in patients with recurrent malignant glioma. The primary outcome measure was time to tumor progression (TTP). Adults with recurrent glioblastoma multiforme or anaplastic glioma were randomized in a 1:1 ratio to receive carboplatin and either RMP-7 or placebo. Radiation therapy had failed in all patients, and they may have received prior chemotherapy. Carboplatin (dosed to achieve an area under the curve of 5 mg/ml x time for patients who had received prior chemotherapy, or 7 mg/ml x time for those who had not) was given intravenously every 4 weeks, followed by intravenous infusion of either RMP-7 or placebo (300 ng/kg). TTP, tumor response, neuropsychological assessments, functional independence, and quality of life assessments were analyzed every 4 weeks. There were 122 patients enrolled, 62 in the RMP-7 and carboplatin group and 60 in the placebo and carboplatin group. Median TTP was 9.7 weeks (95% CI, 8.3-12.6 weeks) for the RMP-7 and carboplatin group and 8.0 weeks (95% CI, 7.4-12.6 weeks) for the placebo and carboplatin group. Median survival times were 26.9 weeks (95% CI, 21.3-37.6 weeks) for the RMP-7 group and 19.9 weeks (95% CI, 15.0-31.3 weeks) for the placebo group. No differences were noted for time to worsening of neuropsychological assessments, functional independence, or quality of life assessments. The use of RMP-7 had no effect on the pharmacokinetics or toxicity of carboplatin. At the dose and schedule used in this trial, RMP-7 did not improve the efficacy of carboplatin. Recent preclinical pharmacokinetic modeling of RMP-7 suggests that higher doses of RMP-7 may be required to increase carboplatin delivery to tumor.

Treatment of primary CNS lymphoma with methotrexate and deferred radiotherapy: a report of NABTT 96-07

PURPOSE

A multicenter, phase II study of single-agent, intravenous methotrexate in newly diagnosed non-AIDS-related primary CNS lymphoma was conducted in the New Approaches to Brain Tumor Therapy (NABTT) CNS Consortium.

METHODS

Methotrexate (8 g/m(2)) was initially administered every 2 weeks. The primary end point was radiographic CR or PR, as defined by standard radiographic criteria, and secondary end points were survival and drug-related toxicity.

RESULTS

Twenty-five patients were enrolled with a mean age of 60 years and median Karnofsky Performance Score of 80. Three of 14 patients who underwent lumbar puncture had malignant cells on CSF cytopathology, and five of 25 patients had ocular involvement. Two patients could not be evaluated for the primary end point because of the absence of measurable disease in one and death before radiologic imaging in another. All patients have completed the treatment program or progressed. Among 23 patients, there were 12 CR (52%), five PR (22%), one (4%) with stable disease, and five progressions (22%) while on therapy. Seven patients died of tumor progression, and two died of other causes. Median progression-free survival was 12.8 months. Median overall survival for the entire group had not been reached at 22.8+ months. The toxicity of this regimen was modest, with no grade 3 or 4 toxicity in 13 of 25 patients, grade 3 toxicity in eight of 25 patients, and grade 4 toxicity in four of 25 patients after 287 cycles of chemotherapy.

CONCLUSION

These results indicate that high-dose methotrexate is associated with modest toxicity and a radiographic response proportion (74%) comparable to more toxic regimens.

L-dopa-resistant parkinsonism syndrome following cerebral radiation therapy for neoplasm

A bradykinetic form of parkinsonism, unresponsive to levo-dopa therapy developed in four patients two to eight weeks after completion of external beam irradiation (39.2 Gy to 59.4 Gy) of their intracranial neoplasm. In the absence of other causative factors, we relate the movement disorder to radiation-induced changes within the basal ganglia. At post-mortem examination one patient had putamenal gliosis and thickened vessels with loss of nigral neurons.

Prodrug activation enzymes in cancer gene therapy

Among the broad array of genes that have been evaluated for tumor therapy, those encoding prodrug activation enzymes are especially appealing as they directly complement ongoing clinical chemotherapeutic regimes. These enzymes can activate prodrugs that have low inherent toxicity using both bacterial and yeast enzymes, or enhance prodrug activation by mammalian enzymes. The general advantage of the former is the large therapeutic index that can be achieved, and of the latter, the non-immunogenicity (supporting longer periods of prodrug activation) and the fact that the prodrugs will continue to have some efficacy after transgene expression is extinguished. This review article describes 13 different prodrug activation schemes developed over the last 15 years, two of which - activation of ganciclovir by viral thymidine kinase and activation of 5-fluorocytosine to 5-fluorouracil - are currently being evaluated in clinical trials. Essentially all of these prodrug activation enzymes mediate toxicity through disruption of DNA replication, which occurs at differentially high rates in tumor cells compared with most normal cells. In cancer gene therapy, vectors target delivery of therapeutic genes to tumor cells, in contrast to the use of antibodies in antibody-directed prodrug therapy. Vector targeting is usually effected by direct injection into the tumor mass or surrounding tissues, but the efficiency of gene delivery is usually low. Thus it is important that the activated drug is able to act on non-transduced tumor cells. This bystander effect may require cell-to-cell contact or be mediated by facilitated diffusion or extracellular activation to target neighboring tumor cells. Effects at distant sites are believed to be mediated by the immune system, which can be mobilized to recognize tumor antigens by prodrug-activated gene therapy. Prodrug activation schemes can be combined with each other and with other treatments, such as radiation, in a synergistic manner. Use of prodrug wafers for intratumoral drug activation and selective permeabilization of the tumor vasculature to prodrugs and vectors should further increase the value of this new therapeutic modality.

Prodrug activation enzymes in cancer gene therapy

Among the broad array of genes that have been evaluated for tumor therapy, those encoding prodrug activation enzymes are especially appealing as they directly complement ongoing clinical chemotherapeutic regimes. These enzymes can activate prodrugs that have low inherent toxicity using both bacterial and yeast enzymes, or enhance prodrug activation by mammalian enzymes. The general advantage of the former is the large therapeutic index that can be achieved, and of the latter, the non-immunogenicity (supporting longer periods of prodrug activation) and the fact that the prodrugs will continue to have some efficacy after transgene expression is extinguished. This review article describes 13 different prodrug activation schemes developed over the last 15 years, two of which - activation of ganciclovir by viral thymidine kinase and activation of 5-fluorocytosine to 5-fluorouracil - are currently being evaluated in clinical trials. Essentially all of these prodrug activation enzymes mediate toxicity through disruption of DNA replication, which occurs at differentially high rates in tumor cells compared with most normal cells. In cancer gene therapy, vectors target delivery of therapeutic genes to tumor cells, in contrast to the use of antibodies in antibody-directed prodrug therapy. Vector targeting is usually effected by direct injection into the tumor mass or surrounding tissues, but the efficiency of gene delivery is usually low. Thus it is important that the activated drug is able to act on non-transduced tumor cells. This bystander effect may require cell-to-cell contact or be mediated by facilitated diffusion or extracellular activation to target neighboring tumor cells. Effects at distant sites are believed to be mediated by the immune system, which can be mobilized to recognize tumor antigens by prodrug-activated gene therapy. Prodrug activation schemes can be combined with each other and with other treatments, such as radiation, in a synergistic manner. Use of prodrug wafers for intratumoral drug activation and selective permeabilization of the tumor vasculature to prodrugs and vectors should further increase the value of this new therapeutic modality.

Happy families: a twin study of humour

The objective of this study was to estimate how much of an individual's appreciation of humour is influenced by genetic factors, the shared environment or the individual's unique environment. A population-based classical twin study of 127 pairs of female twins (71 monozygous (MZ) and 56 dizygous (DZ) pairs) aged 20-75 from the St Thomas' UK Adult Twin Registry elicited responses to five 'Far Side' Larson cartoons on a scale of 0-10. Within both MZ and DZ twin pairs, the tetrachoric correlations of responses to all five cartoons were significantly greater than zero. Furthermore, the correlations for MZ and DZ twins were of similar magnitude and in some cases the DZ correlation was greater than that of the MZ twins. This pattern of correlations suggests that shared environment rather then genetic effects contributes to cartoon appreciation. Multivariate model-fitting confirmed that these data were best explained by a model that allowed for the contribution of the shared environment and random environmental factors, but not genetic effects. However, there did not appear to be a general humour factor underlying responses to all five cartoons and no effect of age was seen. The shared environment, rather than genetic factors, explains the familial aggregation of humour appreciation as assessed by the specific 'off the wall' cognitive type of cartoons used in this study.

Lack of efficacy of 9-aminocamptothecin in adults with newly diagnosed glioblastoma multiforme and recurrent high-grade astrocytoma. NABTT CNS Consortium

9-Aminocamptothecin (9-AC) was administered as a 72-h i.v. infusion every 2 weeks to a total of 99 adults with high-grade astrocytomas. Fifty-one patients with newly diagnosed glioblastoma multiforme received 9-AC treatment prior to radiation therapy and 48 patients with high-grade astrocytomas were treated at the time of tumor recurrence. Upon entrance into these research protocols, all patients had measurable disease that was evaluated on a monthly basis with volumetric CT or MRI scans. A partial response was defined by > or =50% reduction in the contrast enhancing volume on stable or decreasing doses of glucocorticoids. The study specified that all apparent responders would have central review of their radiologic studies and histopathology. The initial patients treated with 9-AC were also receiving anticonvulsants and were noted to have minimal myelosuppression with this chemotherapy. Thus, 9-AC doses were escalated from the previously reported maximum tolerated dose (MTD) of 850 microg/m2/24 h. We then established new MTDs for patients receiving enzyme-inducing anticonvulsants. We defined these MTDs to be 1,776 microg/m2/24 h for newly diagnosed, previously untreated patients and 1,611 microg/m2/24 h for patients with recurrent disease. Twenty-two patients with newly diagnosed glioblastoma multiforme received 9-AC at doses > or =1,776 microg/m2/24 h. Of these, 18 had evaluable disease on central review, and 0 of 18 (0%) demonstrated a partial or complete response. Twenty-one patients with recurrent high-grade astrocytomas were treated at 1,611 microg/m2/24 h; 20 had evaluable disease and 0 of 20 (0%) had a partial or complete response. Thus, the overall response rate in the 38 evaluable patients treated at the MTD was 0 of 38 (0%). Furthermore, of the 51 evaluable patients who were treated at doses less than the MTD, only one partial response was observed, yielding an overall response rate of 2%. Evidence of drug failure was rapid with tumor progression in one-half of patients after 2 drug cycles. 9-AC lacks evidence of substantial activity in patients with newly diagnosed or recurrent high-grade astrocytomas.

Improved delineation of human brain tumors on MR images using a long-circulating, superparamagnetic iron oxide agent

The purpose of this study was to corroborate experimental findings that long-circulating, superparamagnetic iron oxide contrast agents accumulate at the margins of human brain tumors, thereby improving their delineation on magnetic resonance (MR) images. This limited clinical study examined a total of four patients with brain tumors (three with primary gliomas and one with metastatic melanoma; n = 8 lesions) who were given a pharmaceutical formulation of a superparamagnetic, ultra-small-particulate iron oxide (USPIO, intravenous dose of 1.1 mg Fe/kg). The agent has a characteristically long plasma half-life and is currently undergoing Phase III clinical trials for liver disease (AMI-227, Advanced Magnetics, Cambridge, MA). MR (conventional spin-echo and gradient-echo) images of the brain were obtained before and 12, 24, and/or 36 hours after administration of the agent, with follow-up several weeks later. Twelve to 36 hours after IV administration of the USPIO, both primary and metastatic brain tumors showed readily detectable increases in signal intensity on T1-weighted spin-echo images. Unlike the pattern of enhancement with a gadolinium (Gd) chelate, which occurred immediately and decreased within hours, that with the USPIO occurred gradually, with a peak at 24 hours, and decreased over several days. Whereas the enhancing tumor margin with the Gd chelate blurred with time due to diffusion of the agent, the margin with the USPIO remained sharp, presumably due to the much lower diffusion coefficient (large size) of the particles and partly because of local endocytosis by tumor cells. Compared with Gd chelates, long-circulating, superparamagnetic iron oxide contrast agents can provide prolonged delineation of the margins of human brain tumors on MR images, which has implications for the targeting of diagnostic biopsies and the planning of surgical resections.

Increased 9-aminocamptothecin dose requirements in patients on anticonvulsants. NABTT CNS Consortium. The New Approaches to Brain Tumor Therapy

BACKGROUND

High grade astrocytomas remain uniformly fatal despite aggressive surgery and radiotherapy. As existing chemotherapeutic agents are of limited benefit, clinical trials are underway to screen new drugs, such as 9-aminocamptothecin (9-AC), for activity in high grade astrocytomas.

PURPOSE

This study was designed to estimate the efficacy of 9-AC in patients with newly diagnosed glioblastoma multiforme and recurrent high grade astrocytomas. The planned dose of 9-AC for this trial was 850 microg/m2 per 24 h as a 72-h continuous intravenous infusion every 2 weeks. This was the maximum tolerated dose (MTD) on this schedule in multiple phase I studies in patients with systemic malignancies. However, we found this dose subtherapeutic in our patient population. As a result, the purpose of the study was altered to determine the MTD.

METHODS

A group of 32 patients were studied using 850 microg/m2 per 24 h with a provision to escalate to 1000 microg/m2 per 24 h if the first three cycles of 9-AC were without significant hematologic toxicity. Once it was determined that myelosuppression did not occur in patients on anticonvulsants, dose escalations were initiated using the continual reassessment method. Dose escalations were conducted independently in newly diagnosed and recurrent patients and in those taking and not taking hepatic enzyme-inducing anticonvulsants. Pharmacologic studies were conducted during the first cycle of 9-AC. Toxicity was determined using the NCI common toxicity criteria and efficacy was assessed using serial volumetric brain scans.

RESULTS

9-AC was administered to 59 patients, 31 with newly diagnosed glioblastoma multiforme and 28 with recurrent high grade astrocytomas. No grade III-IV myelosuppression was noted in the 29 patients (128 cycles) on phenytoin, carbamazepine, phenobarbital, and/ or valproic acid who received 850 microg/m2 per 24 h. In contrast, two of three patients (five cycles) who were not taking anticonvulsants developed grade IV myelosuppression. Steady-state total 9-AC plasma levels were lower in patients on anticonvulsants (median 25.3 nM) than in patients who were not taking anticonvulsants (median 76.5 nM). Dose escalations performed in 27 additional patients determined the MTD in patients taking anticonvulsants to be 1776 microg/m2 per 24 h for patients with newly diagnosed tumors and 1611 microg/m2 per 24 h for patients with recurrent disease.

CONCLUSIONS

We describe a new and unexpected drug interaction between 9-AC and anticonvulsants. This is similar to recent findings with paclitaxel, and suggests that higher than "usual" doses of some chemotherapeutic agents are required in patients on anticonvulsants. Prospectively defined dose escalations and pharmacologic studies are essential for the careful evaluation of new chemotherapeutic agents in patients with brain tumors.

High-dose intravenous methotrexate for patients with nonleukemic leptomeningeal cancer: is intrathecal chemotherapy necessary?

PURPOSE

Standard treatments for neoplastic meningitis are only modestly effective and are associated with significant morbidity. Isolated reports suggest that concurrent systemic and intrathecal (i.t.) therapy may be more effective than i.t. therapy alone. We present our experience, which includes CSF and serum pharmacokinetic data, on the use of high-dose (HD) intravenous (i.v.) methotrexate (MTX) as the sole treatment for neoplastic meningitis.

PATIENTS AND METHODS

Sixteen patients with solid-tumor neoplastic meningitis received one to four courses (mean, 2.3 courses) of HD (8 g/m2 over 4 hours) i.v. MTX and leucovorin rescue. Serum and CSF MTX concentrations were measured daily. Toxicity, response, and survival were retrospectively compared with a reference group of 15 patients treated with standard i.t. MTX during the same time interval.

RESULTS

Peak methotrexate concentrations ranged from 3.7 to 55 micromol/L (mean, 17.1 micromol/L) in CSF and 178 to 1,700 micromol/L (mean, 779 micromol/L) in serum. Cytotoxic CSF and serum MTX concentrations were maintained much longer than with i.t. dosing. Toxicity was minimal. Cytologic clearing was seen in 81% of patients compared with 60% of patients treated intrathecally (P = .3). Median survival in the HD i.v. MTX group was 13.8 months versus 2.3 months in the i.t. MTX group (P = .003).

CONCLUSION

HD i.v. MTX is easily administered and well tolerated. This regimen achieves prolonged cytotoxic serum MTX concentrations and CSF concentrations at least comparable to those achieved with standard i.t. therapy. Cytologic clearing and survival may be superior in patients treated with HD i.v. MTX. Prospective studies and a reconsideration of the use of i.t. chemotherapy for patients with neoplastic meningitis are warranted.

Perfusion Magnetic Resonance Imaging to Assess Brain Tumor Responses to New Therapies

BACKGROUND: Although magnetic resonance imaging (MRI) is effective in detecting the location of intracranial tumors, new imaging techniques have been studied that may enhance the specificity for the prediction of histologic grade of tumor and for the distinction between recurrence and tumor necrosis associated with cancer therapy. METHODS: The authors review their experience and that of others on the use of perfusion magnetic resonance imaging to evaluate responses of brain tumors to new therapies. RESULTS: Functional imaging techniques that can distinguish tumor from normal brain tissue using physiological parameters. These new approaches provide maps of tumor perfusion to monitor the effects of novel compounds that restrict tumor angiogenesis. CONCLUSIONS: Perfusion MRI not only may be as effective as radionuclide-based techniques in sensitivity and specificity in assessing brain tumor responses to new therapies, but also may offer higher resolution and convenient co-registration with conventional MRI, as well as time- and cost-effectiveness. Further study is needed to determine the role of perfusion MRI in assessing brain tumor responses to new therapies.

Treatment of recurrent malignant glioma with BCNU-fluosol and oxygen inhalation. A phase I-II study

OBJECTIVES

To evaluate the toxicity and response rate following BCNU with oxygen inhalation and escalating dosages of fluosol administered to patients with radiographic progression of malignant glioma after definitive surgery and radiotherapy.

METHOD

This single arm, phase I-II multicenter trial, enrolled 99 patients with malignant gliomas recurrent after definitive surgery and radiotherapy. All patients received a fixed dose (200 mg/m2) of BCNU along with 100% oxygen and fluosol, a perfluorochemical. Fluosol doses were escalated between patients (150, 275, 400 and 600 ml/m2). Treatment was repeated every 6 weeks for a maximum of 6 cycles. Patients were assessed for toxicity at the time of infusion and sequentially thereafter. Response was evaluated clinically and radiologically at least every 6 weeks.

RESULTS

Treatment was well tolerated. Dose reductions were required at least once in 18 patients, treatment delays were necessary at least once in 33 patients. Grade 3-4 leukopenia occurred in 6 patients (12 events), grade 3-4 thrombocytopenia in 10 patients (25 events) and grade 3-4 liver enzymes elevations in 18 patients (31 events). Higher fluosol dosages did not produce increases in toxicity or responses. Response or stabilization was seen in 57% (38% were stabilizations) of the patients who entered the trial with progressive disease. The median time to progression was 45 weeks, and median survival was 66 weeks for patients who had response or stabilization. For patients with glioblastoma response/stabilization was seen in 45% with a mean duration of 24 weeks, for patients with anaplastic astrocytoma response/stabilization was seen in 68% with a mean duration of 50 weeks.

CONCLUSION

This treatment regimen is well tolerated. Our results suggest fluosol may enhance the effectiveness of BCNU for the treatment of recurrent malignant gliomas. Future studies will be performed using fluosol at the dose of 400 ml/m2.

Late motor deficits of Chilean manganese miners: a blinded control study

High-level chronic manganese (Mn) exposure produces dystonic rigidity and proximal tremor. The late effects of asymptomatic exposure are uncertain. To evaluate hand movements of asymptomatic Chilean miners, we utilized a manual tremormeter (EAP) and a digitizing tablet (MOVEMAP). In Andacollo, Chile, we examined 59 individuals aged > 50 years (mean age, 64.4 years). Twenty-seven exposed miners had heavy Mn dust exposure in Mn mines for more than 5 years (mean duration, 20.25 years), ending at least 5 years previously. Thirty-two control miners had never worked in Mn mines or had short-term Mn employment. Tests of resting tremor (EAP Tremormeter, MOVEMAP Steady paradigm), action tremor (MOVEMAP Square paradigm), and repetitive hand movements (EAP Tapping Test and Orthokinesimeter) differentiated performance of exposed miners from that of controls. Chronic asymptomatic Mn exposure results in detectable late-life abnormalities of movement.

Sentinel lesions of primary CNS lymphoma

Some patients ultimately diagnosed with primary CNS lymphoma (PCNSL) have transient symptomatic contrast enhancing lesions. These "sentinel lesions" of PCNSL recede spontaneously or with corticosteroid treatment and present an important diagnostic dilemma because they show variable, but non-diagnostic histopathological features. Four previously healthy, immunocompetent patients aged 49 to 58 years had contrast enhancing intraparenchymal brain lesions. Before biopsy, three of the four were treated with corticosteroids. Initial biopsies showed demyelination with axonal sparing in two, non-specific inflammation in one, and normal brain in one. Infiltrating lymphocytes predominantly expressed T cell markers with rare B cells. All four patients recovered within two to four weeks after the initial biopsy and imaging studies showed resolution of the lesions. The CSF was normal in three of the four patients tested; oligoclonal bands were absent in both of the two tested. After seven to 11 months, each patient developed new symptomatic lesions in a different region of the brain, biopsy of which showed a B cell PCNSL. The mechanism of spontaneous involution of sentinel lesions is not understood, but may represent host immunity against the tumour. Sentinel lesions of PCNSL should be considered in patients with contrast enhancing focal parenchymal lesions that show non-specific or demyelinative histopathological changes. Close clinical and radiographic follow up is essential if PCNSL is to be diagnosed early in such patients.