[Show abstract][Hide abstract] ABSTRACT: To carry out a further survey of archived appendix samples to understand better the differences between existing estimates of the prevalence of subclinical infection with prions after the bovine spongiform encephalopathy epizootic and to see whether a broader birth cohort was affected, and to understand better the implications for the management of blood and blood products and for the handling of surgical instruments.
Irreversibly unlinked and anonymised large scale survey of archived appendix samples.
Archived appendix samples from the pathology departments of 41 UK hospitals participating in the earlier survey, and additional hospitals in regions with lower levels of participation in that survey.
32 441 archived appendix samples fixed in formalin and embedded in paraffin and tested for the presence of abnormal prion protein (PrP).
Of the 32 441 appendix samples 16 were positive for abnormal PrP, indicating an overall prevalence of 493 per million population (95% confidence interval 282 to 801 per million). The prevalence in those born in 1941-60 (733 per million, 269 to 1596 per million) did not differ significantly from those born between 1961 and 1985 (412 per million, 198 to 758 per million) and was similar in both sexes and across the three broad geographical areas sampled. Genetic testing of the positive specimens for the genotype at PRNP codon 129 revealed a high proportion that were valine homozygous compared with the frequency in the normal population, and in stark contrast with confirmed clinical cases of vCJD, all of which were methionine homozygous at PRNP codon 129.
This study corroborates previous studies and suggests a high prevalence of infection with abnormal PrP, indicating vCJD carrier status in the population compared with the 177 vCJD cases to date. These findings have important implications for the management of blood and blood products and for the handling of surgical instruments.
[Show abstract][Hide abstract] ABSTRACT: Anonymous screening of lymphoreticular tissues removed during routine surgery has been applied to estimate the UK population prevalence of asymptomatic vCJD prion infection. The retrospective study of Hilton et al (J Pathol 2004; 203: 733-739) found accumulation of abnormal prion protein in three formalin-fixed appendix specimens. This led to an estimated UK prevalence of vCJD infection of ∼1 in 4000, which remains the key evidence supporting current risk reduction measures to reduce iatrogenic transmission of vCJD prions in the UK. Confirmatory testing of these positives has been hampered by the inability to perform immunoblotting of formalin-fixed tissue. Animal transmission studies offer the potential for 'gold standard' confirmatory testing but are limited by both transmission barrier effects and known effects of fixation on scrapie prion titre in experimental models. Here we report the effects of fixation on brain and lymphoreticular human vCJD prions and comparative bioassay of two of the three prevalence study formalin-fixed, paraffin-embedded (FFPE) appendix specimens using transgenic mice expressing human prion protein (PrP). While transgenic mice expressing human PrP 129M readily reported vCJD prion infection after inoculation with frozen vCJD brain or appendix, and also FFPE vCJD brain, no infectivity was detected in FFPE vCJD spleen. No prion transmission was observed from either of the FFPE appendix specimens. The absence of detectable infectivity in fixed, known positive vCJD lymphoreticular tissue precludes interpreting negative transmissions from vCJD prevalence study appendix specimens. In this context, the Hilton et al study should continue to inform risk assessment pending the outcome of larger-scale studies on discarded surgical tissues and autopsy samples.
Full-text · Article · Mar 2011 · The Journal of Pathology
[Show abstract][Hide abstract] ABSTRACT: Defining the causal relationship between a microbe and encephalitis is complex. Over 100 different infectious agents may cause encephalitis, often as one of the rarer manifestations of infection. The gold-standard techniques to detect causative infectious agents in encephalitis in life depend on the study of brain biopsy material; however, in most cases this is not possible. We present the UK perspective on aetiological case definitions for acute encephalitis and extend them to include immune-mediated causes. Expert opinion was primarily used and was supplemented by literature-based methods. Wide usage of these definitions will facilitate comparison between studies and result in a better understanding of the causes of this devastating condition. They provide a framework for regular review and updating as the knowledge base increases both clinically and through improvements in diagnostic methods. The importance of new and emerging pathogens as causes of encephalitis can be assessed against the principles laid out here.
Full-text · Article · Apr 2010 · Epidemiology and Infection
[Show abstract][Hide abstract] ABSTRACT: To establish with improved accuracy the prevalence of disease related prion protein (PrP(CJD)) in the population of Britain and thereby guide a proportionate public health response to limit the threat of healthcare associated transmission of variant Creutzfeldt-Jakob disease (vCJD).
Cross sectional opportunistic survey. Study samples Anonymised tonsil pairs removed at elective tonsillectomy throughout England and Scotland.
National anonymous tissue archive for England and Scotland.
Presence of PrP(CJD) determined by using two enzyme immunoassays based on different analytical principles, with further investigation by immunohistochemistry or immunoblotting of any samples reactive in either assay.
Testing of 63 007 samples was completed by the end of September 2008. Of these, 12 753 were from the birth cohort in which most vCJD cases have arisen (1961-85) and 19 908 were from the 1986-95 cohort that would have been also exposed to bovine spongiform encephalopathy through infected meat or meat products. None of the samples tested was unequivocally reactive in both enzyme immunoassays. Only two samples were reactive in one or other enzyme immunoassay and equivocal in the other, and nine samples were equivocally reactive in both enzyme immunoassays. Two hundred and seventy six samples were initially reactive in one or other enzyme immunoassay; the repeat reactivity rate was 15% or less, depending on the enzyme immunoassay and cut-off definition. None of the samples (including all the 276 initially reactive in enzyme immunoassay) that were investigated by immunohistochemistry or immunoblotting was positive for the presence of PrP(CJD).
The observed prevalence of PrP(CJD) in tonsils from the 1961-95 combined birth cohort was 0/32 661 with a 95% confidence interval of 0 to 113 per million. In the 1961-85 cohort, the prevalence of zero with a 95% confidence interval of 0 to 289 per million was lower than, but still consistent with, a previous survey of appendix tissue that showed a prevalence of 292 per million with a 95% confidence interval of 60 to 853 per million. Continuing to archive and test tonsil specimens, especially in older birth cohorts, and other complementary large scale anonymous tissue surveys, particularly of post-mortem tissues, will further refine the calculated prevalence of PrP(CJD).
[Show abstract][Hide abstract] ABSTRACT: Nerve biopsy is used as part of the investigation of patients with peripheral neuropathy and is particularly useful in confirming the diagnosis of peripheral nerve vasculitis. Previous studies have suggested that sampling the peroneal nerve, in combination with peroneus brevis, is more sensitive than the sural nerve for this diagnosis but there are no published data on the complication rate of peroneal nerve biopsies. We have assessed the complications in 50 patients undergoing nerve biopsy, and have shown that although biopsy of the peroneal nerve may result in a larger area of sensory loss in some patients, other complications are not increased when compared with sural nerve biopsy.
Preview · Article · Dec 2007 · Journal of neurology, neurosurgery, and psychiatry
[Show abstract][Hide abstract] ABSTRACT: To perform prion protein gene (PRNP) codon 129 analysis in DNA extracted from appendix tissue samples that had tested positive for disease associated prion protein.
Reanalysis of positive cases identified in a retrospective anonymised unlinked prevalence study of variant Creutzfeldt-Jakob disease (vCJD) in the United Kingdom. STUDY SAMPLES: Three positive appendix tissue samples out of 12,674 samples of appendix and tonsil tested for disease associated prion protein. The patients from whom these samples were obtained were aged 20-29 years at the time of surgery, which took place in 1996-9.
Pathology departments in two tertiary centres in England and Scotland.
Adequate DNA was available for analysis in two of the three specimens, both of which were homozygous for valine at codon 129 in the PRNP.
This is the first indication that the valine homozygous subgroup at codon 129 in the PRNP is susceptible to vCJD infection. All tested clinical cases of vCJD have so far occurred in the methionine homozygous subgroup, and a single case of probable iatrogenic vCJD infection has been identified in one patient who was a methionine/valine heterozygote at this genetic locus. People infected with vCJD with a valine homozygous codon 129 PRNP genotype may have a prolonged incubation period, during which horizontal spread of the infection could occur either from blood donations or from contaminated surgical instruments used on these individuals during the asymptomatic phase of the illness.
[Show abstract][Hide abstract] ABSTRACT: In the late 1980s and early 1990s, there was widespread exposure of the UK population to bovine spongiform encephalopathy (BSE)-contaminated food products, which has led to over 150 deaths from variant Creutzfeldt-Jakob disease (vCJD). Although the pathogenesis in humans is not fully understood, data from animal models and, to a lesser extent, patients with vCJD suggest that oral exposure to BSE is rapidly followed by accumulation of PrP(res) in gut-associated lymphoid tissue, then, after haematogenous spread, throughout the lymphoreticular system. Spread to the central nervous system may not occur for several years, but blood from individuals in the pre-clinical phase appears to be able to transmit disease. The incidence of vCJD has remained low and is in decline, but it is known from iatrogenic CJD and kuru that human prion disease can have incubation periods of up to 40 years. Cases of vCJD are therefore likely to occur for many more years and alternative phenotypes may develop in individuals with different PRNP genotypes to those seen to date. Studies in transgenic mice have shown that sub-clinical infection is frequent following oral exposure to BSE and a study looking at the accumulation of PrP in anonymized human lymphoid tissue samples found positive cases. There are likely to be a number of asymptomatic 'carriers' of disease within the UK and although it is unclear whether these individuals will develop clinical disease, there is a potential for iatrogenic spread to others. These uncertainties highlight the importance of developing a reliable blood test for vCJD and the continued need for surveillance.
No preview · Article · Jan 2006 · The Journal of Pathology
[Show abstract][Hide abstract] ABSTRACT: Idiopathic or primary angiitis of the CNS (PACNS) and cerebral amyloid angiopathy (CAA) are unusual vasculopathies generally regarded as unrelated disorders. A few case reports have, however, described granulomatous angiitis in patients with sporadic, amyloid beta peptide (Abeta)-related CAA. Here we describe the clinical, neuroradiological and neuropathological features of nine patients with Abeta-related angiitis (ABRA). Combining these with the individual case reports drawn from the literature has allowed us to define ABRA as a clinical entity and to compare its features with those of PACNS. The mean age of presentation of ABRA (67 years) is higher than that of PACNS but lower than that of sporadic non-inflammatory Abeta-related CAA. Alterations in mental status (59%), headaches (35%), seizures and focal neurological deficits (24%) are common. Hallucinations are a presenting manifestation in 12% of cases. Most patients have white matter hyperintensities on MRI but these are of similar appearance to those in PACNS. Cerebrospinal fluid usually shows modest elevation of protein and pleocytosis. Neuropathology reveals angiodestructive inflammation, often granulomatous, and meningeal lymphocytosis. Abeta is consistently present in abundance in affected blood vessels but usually scanty within the parenchyma of the cerebral cortex. However, the cortex includes numerous activated microglia, occasionally in a plaque-like distribution and containing cytoplasmic Abeta. The cerebral white matter shows patchy gliosis and rarefaction, in some cases marked. Our findings (i) help to dissect one separate clinicopathological entity from what is likely to be a spectrum of primary angiitides of the CNS; (ii) have important therapeutic implications for one category of patients with amyloid-related vasculopathy; and (iii) may provide valuable insights into the development of amyloid-associated inflammation, of relevance not only to ABRA but also to Abeta-immunization-related encephalitis and to Alzheimer's disease.
[Show abstract][Hide abstract] ABSTRACT: This study aims to provide an estimate of the number of individuals in the UK who may be incubating variant Creutzfeldt-Jakob disease and at risk of causing iatrogenic spread of the disease. Lymphoreticular accumulation of prion protein is a consistent feature of variant Creutzfeldt-Jakob at autopsy and has also been demonstrated in the pre-clinical phase. Immunohistochemical accumulation of prion protein in the lymphoreticular system remains the only technique that has been shown to predict neurological disease reliably in animal prion disorders. In this study, immunohistochemistry was used to demonstrate the presence of prion protein, with monoclonal antibodies KG9 and 3F4, in surgically removed tonsillectomy and appendicectomy specimens. The samples were collected from histopathology departments across the UK and anonymised prior to testing. Samples were tested from 16 703 patients (14 964 appendectomies, 1739 tonsillectomies), approximately 60% of whom were from the age group 20-29 years at operation. Twenty-five per cent of the samples were excluded from the final analyses because they contained inadequate amounts of lymphoid tissue. Three appendicectomy samples showed lymphoreticular accumulation of prion protein, giving an estimated prevalence of 3/12 674 or 237 per million (95% CI 49-692 per million). The pattern of lymphoreticular accumulation in two of these samples was dissimilar from that seen in known cases of variant Creutzfeldt-Jakob disease. Although it is uncertain whether immunohistochemical accumulation of prion protein in the lymphoreticular system is specific for variant Creutzfeldt-Jakob disease, it has not been described in any other disease, including other forms of human prion disease or a range of inflammatory and infective conditions. These findings reinforce the importance of measures taken by the UK Department of Health to reduce the risk of spread of variant Creutzfeldt-Jakob via blood products and surgical instruments, and of the urgency to proceed with large-scale screening of fresh tonsil specimens for the presence of prion protein.
Preview · Article · Jul 2004 · The Journal of Pathology
[Show abstract][Hide abstract] ABSTRACT: To assess the potential prognostic significance of a range of molecular and morphological parameters in glioblastomas that can be applied in the setting of a routine diagnostic neuropathology laboratory.
A consecutive series of 107 adult glioblastomas were studied. Retinoblastoma and deleted-in-colon cancer (DCC) protein expression were assessed using immunocytochemistry and chromosome 10 loss by in-situ hybridization. Loss of retinoblastoma expression was associated with a worse outcome, which appeared to be independent of age. There was no significant association between chromosome 10 loss or DCC protein expression and survival. Survival was significantly increased in the 5% of patients whose tumours had focal morphological features suggesting oligodendroglial differentiation.
Glioblastomas containing areas of oligodendroglial differentiation or showing widespread immunocytochemical expression of retinoblastoma protein have a better prognosis than those without these features.
[Show abstract][Hide abstract] ABSTRACT: The classification and grading of intrinsic brain tumours is still predominantly based upon morphological appearance. However, it is now apparent that tumours can be further subdivided by their genetic make-up. Genetic subtyping may be carried out either directly by DNA/RNA analysis, or indirectly by looking for immunocytochemical expression of the gene product. Genetic subtyping can add important information about the prognosis, aetiology or responsiveness to treatment of certain tumours, which is of particular importance for anaplastic oligodendrogliomas, where assessment of chromosome 1p and 19q status provides additional prognostic information, and also predicts the likelihood of tumour chemosensitivity. Genetic characterization may also aid in the diagnosis of certain tumours, for example demonstration of INI1 mutations helps to separate atypical teratoid/malignant rhabdoid tumours from most other primitive malignant brain tumours. With the rapid growth in our understanding of the significance of the genetic changes found in tumours, alongside the development of targeted therapies, it is likely that genetic analyses will soon become a routine part of the assessment of brain tumours.
No preview · Article · Apr 2004 · Current Diagnostic Pathology
[Show abstract][Hide abstract] ABSTRACT: Immunocytochemical accumulation of prion protein (PrP) in lymphoid tissues is a feature of variant Creutzfeldt-Jakob disease (vCJD) that has been used both to aid in the diagnosis of patients and as a basis of large scale screening studies to assess the prevalence of preclinical disease in the UK. However, the specificity of this approach is unknown.
To assess the specificity of lymphoreticular accumulation of PrP for vCJD by examining a range of human diseases.
Paraffin wax embedded lymphoreticular tissues from patients with several reactive conditions (58 cases), tumours (27 cases), vCJD (54 cases), and other human prion diseases (56 cases) were assessed. PrP accumulation was assessed by immunocytochemistry using two different monoclonal anti-PrP antibodies and a sensitive detection system.
All cases of vCJD showed widespread lymphoreticular accumulation of PrP; however, this was not seen in the other conditions examined.
Lymphoreticular accumulation of PrP, as assessed by immunocytochemistry, appears to be a highly specific feature of vCJD.
[Show abstract][Hide abstract] ABSTRACT: The authors report the neuropathologic findings in a case of Sneddon's syndrome. There were multiple small, predominantly cortical, infarcts, with focal hyperplasia and fibrotic occlusion of arterial vessels in the superficial white matter, cortex, and leptomeninges. A very occasional arterial thrombus was seen. These findings suggest that Sneddon's syndrome is caused by a noninflammatory arteriopathy affecting superficial cerebral vessels.
[Show abstract][Hide abstract] ABSTRACT: Variant Creutzfeldt-Jakob disease is almost certainly caused by the bovine spongiform encephalopathy agent, and although the disease is rare (115 deaths to date) there is uncertainty about future numbers of cases.1 The lack of a conventional immune response and the inability to detect abnormal prion protein in blood has hampered the development of a blood test.1 Lymphoreticular accumulation of prion protein has been used as a preclinical test for scrapie (the form of the disease in sheep and goats) and is a consistent feature of variant Creutzfeldt-Jakob disease, occurring before the onset of symptoms.2–4 We screened large numbers of specimens from appendicectomies and tonsillectomies for the presence of prion protein in lymphoreticular tissue to determine the number of people with preclinical variant Creutzfeldt-Jakob disease.
Methods and results
We retrieved appendix and tonsil samples removed between 1995 and 1999 from patients aged 10-50 from histopathology departments across the United Kingdom. The samples were anonymised before testing. We also examined appendix samples removed at autopsy or at surgery from patients with variant Creutzfeldt-Jakob disease. Prion protein was detected by immunohistochemistry with monoclonal antibodies 3F4 (Dako, Ely, Cambridge) and KG9 (Institute for Animal Health, Newbury) and visualised with the catalysed signal amplification system (Dako). We excluded cases with fewer than five secondary lymphoid follicles from the final analyses because in the previously reported case and those examined at autopsy, prion protein was present in around 20% of follicles.4 We tested 11 228 samples, of which 2910 were excluded. Most samples were appendixes and 70% were from patients aged 20-29. In one case we identified prion protein immunoreactivity in a single lymphoid follicle stained with KG9 (figure). The pattern of staining was similar to that seen in the two other patients who developed variant Creutfeldt-Jakob disease (figure1).4 This positive staining was less evident in sections stained with 3F4 antibody. The reason for this discrepancy is not clear but may be due to sampling error because of the focal nature of prion protein deposition. In the appendixes removed before the onset of symptoms in three patients with variant Creutfeldt-Jakob disease, two (removed in 1995 and 1996; see figure) were positive, and the third (removed in 1987) was negative.4 Overall, 19 of 20 appendixes removed at autopsy from cases of variant Creutzfeldt-Jakob disease with adequate numbers of lymphoid follicles had lymphoreticular accumulation of prion protein.
View larger version:In a new windowDownload as PowerPoint SlideView larger version:In a new windowDownload as PowerPoint Slide(Left) Distribution of coarse granular prion protein within lymphoid follicle of appendix, suggestive of follicular dendritic cells. (Right) Lymphoreticular accumulation of prion protein in appendix tissue from patient with Creutzfeldt-Jakob disease, removed two years before onset of symptoms
One appendix showing the lymphoreticular accumulation of prion protein out of 8318 samples tested gives an estimated detectable prevalence of prion protein accumulation of 120 per million (95% confidence interval, 0.5 to 900) among people aged 10-50 between 1995 and 1999. Our study design precluded transmission studies, but the accumulation of prion protein in lymphoreticular tissue detected by the immunohistochemical technique correlates with the detection of abnormal prion protein by western blotting and remains the only technique shown to reliably predict disease in animals. 2 3 5 The sensitivity and specificity of preclinical lymphoreticular accumulation of prion protein in predicting variant Creutzfeldt-Jakob disease are unknown, but in sheep exposed to scrapie are estimated to be 87% and 94%, respectively.5 At autopsy, 95% of appendixes from patients with variant Creutzfeldt-Jakob disease with adequate amounts of lymphoid tissue showed accumulation of prion protein, as did both appendixes removed during the 1990s from patients who later developed the disease.
We provide the first estimate of the number of people who may be a potential source of variant Creutzfeldt-Jakob disease by iatrogenic spread. Large scale prospective screening of tissue from tonsillectomies is needed to obtain precise data on prevalence. The use of fresh tissue would allow for a semi-automated western blot assay and verification of positive samples by transmission studies. As half of tonsillectomies are in children under 10, who will have had little or no exposure to bovine spongiform encephalopathy, the opportunity for such a study will diminish over time.
We thank histopathology departments and relatives of patients with variant Creutzfeldt-Jakob disease who gave consent for autopsy tissues to be used as positive control material.
Contributors: DAH designed the English study, screened samples tested at Plymouth, and drafted the manuscript; he will act as guarantor for the paper. JWI designed the Scottish study, screened samples tested at Edinburgh, and contributed to the manuscript. ACG performed the statistical analyses and contributed to the manuscript. MP, LC, and PE performed the technical work at Plymouth. LMcC and DR performed the technical work and assisted in screening samples at Edinburgh.
Funding Department of Health and the Royal Society. The views expressed in this publication are those of the authors and not necessarily those of the Department of Health.
Competing interests None declared.References1.↵Collinge J.Variant Creutzfeldt-Jakob disease.Lancet 1999;354: 317–323.OpenUrlCrossRefMedlineWeb of Science2.↵Schreuder BEC, van Keulen LJM, Vromans MEW, Langeveld JPM, Smits MA.Preclinical test for prion diseases.Nature 1996;381: 563.OpenUrlCrossRefMedline3.↵Hill AF, Butterworth RJ, Joiner S, Jackson G, Rosser MN, Thomas DJ, et al.Investigation of variant Creutzfeldt-Jakob disease and other human prion disease with tonsil biopsy samples.Lancet 1999;353: 183–189.OpenUrlCrossRefMedlineWeb of Science4.↵Hilton DA, Fathers E, Edwards P, Ironside JW, Zajicek J.Prion immunoreactivity in appendix before clinical onset of variant Creutzfeldt-Jakob disease.Lancet 1998;352: 703–704.OpenUrlCrossRefMedlineWeb of Science5.↵O'Rourke KI, Baszler TV, Besser TE, Miller JM, Cutlip RC, Wells GAH, et al.Preclinical diagnosis of scrapie by immunohistochemistry of third eyelid lymphoid tissue.J Clin Microbiol 2000;38: 3254–3259.OpenUrlFREE Full Text
[Show abstract][Hide abstract] ABSTRACT: Angiogenesis is a prominent feature of glioblastomas but the mechanisms involved in the control of this process are poorly understood. We have investigated the potential role of a recently described transcription factor, hypoxia-inducible factor 1 (HIF-1), which initiates the transcription of a number of hypoxia-inducible genes, including those encoding vascular endothelial growth factor and its receptors. HIF-1 protein expression was assessed by immunocytochemistry, using a monoclonal antibody to the alpha subunit (HIF-1alpha). HIF-1 mRNA expression was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR) and the ribonuclease protection assay (RPA). Strong nuclear expression of HIF-1alpha protein was seen in the majority of glioblastomas and anaplastic astrocytomas, particularly surrounding areas of necrosis in glioblastomas. In the majority of these tumours upregulation of HIF-1alpha mRNA was also demonstrated, with a significant increase in glioblastomas compared to lower grade tumours. No correlation was found between the presence of HIF-1alpha protein and immunohistochemical expression of p53 protein. These findings are in keeping with an important role of HIF-1alpha in the vascularization of glioblastomas and suggest that upregulation is at least partly at a transcriptional level.
No preview · Article · Jul 2002 · Neuropathology and Applied Neurobiology
[Show abstract][Hide abstract] ABSTRACT: Angiogenesis is a prominent feature of glioblastomas but the mechanisms involved in the control of this process are poorly understood. We have investigated the potential role of a recently described transcription factor, hypoxia-inducible factor 1 (HIF-1), which initiates the transcription of a number of hypoxia-inducible genes, including those encoding vascular endothelial growth factor and its receptors. HIF-1 protein expression was assessed by immunocytochemistry, using a monoclonal antibody to the α subunit (HIF-1α). HIF-1 mRNA expression was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR) and the ribonuclease protection assay (RPA). Strong nuclear expression of HIF-1α protein was seen in the majority of glioblastomas and anaplastic astrocytomas, particularly surrounding areas of necrosis in glioblastomas. In the majority of these tumours upregulation of HIF-1α mRNA was also demonstrated, with a significant increase in glioblastomas compared to lower grade tumours. No correlation was found between the presence of HIF-1α protein and immunohistochemical expression of p53 protein. These findings are in keeping with an important role of HIF-1α in the vascularization of glioblastomas and suggest that upregulation is at least partly at a transcriptional level.
No preview · Article · Jun 2002 · Neuropathology and Applied Neurobiology
[Show abstract][Hide abstract] ABSTRACT: Diffuse astrocytomas have a median survival of 6-8 years. However, in a minority of cases that are histologically low grade, progression is rapid, leading to death within 2 years. Loss of p16, retinoblastoma protein, and deleted-in-colon-carcinoma protein expression, and monosomy of chromosome 10 have been shown to occur in malignant astrocytic tumors. We have investigated the prognostic value of expression of these markers, using techniques applicable in many histopathology laboratories, in diffuse astrocytomas that are histologically low grade. Paraffin sections from 71 diffuse, supratentorial, low-grade astrocytomas, from patients with at least 8-year survival data, were immunostained with antibodies to p16, deleted-in-colon-carcinoma protein, p53, Ki67, and retinoblastoma protein. In situ hybridization with a digoxigenin-labeled probe to chromosome 10 was used to assess chromosomal loss. In most cases there was immunostaining of virtually all tumor cell nuclei with antibodies to p16 and retinoblastoma protein. Three of the 68 tumors in which assessment of p16 was possible included discrete foci with lack of detectable immunoreactivity in tumor cells. The three patients concerned had a significantly shortened median survival (1.1 years vs 4.4 years in those without loss of p16; p <0.01). In six of the 61 cases where assessment of retinoblastoma protein was possible, <70% of tumor cell nuclei showed immunoreactivity. These six patients had a shorter survival (4.0 years) than had the remaining patients (5.4 years), although this difference was not statistically significant. The tumor from one of these patients included areas where only 36% of tumor cells showed retinoblastoma protein immunoreactivity, and this patient survived only 1.5 years. Tumors showing loss of both p16 and retinoblastoma were not seen. p53 and deleted-in-colon-carcinoma protein expression was highly variable and did not correlate with survival. Tumors with monosomy for chromosome 10 were not identified. Both polyploidy and the Ki67 labeling index were significantly associated with the p53 labeling index but not with survival. Focal loss of p16 or retinoblastoma protein is demonstrable in approximately 5% and 10% of diffuse low-grade diffuse astrocytomas, respectively. Tumors with focal loss of immunoreactivity for these proteins are associated with shorter survival than those without, suggesting that immunohistochemistry for p16 and retinoblastoma protein may be a useful adjunct to other methods for assessing the prognosis of astrocytomas.
No preview · Article · May 2002 · American Journal of Surgical Pathology