Telepathology: current status and future prospects in diagnostic histopathology

Telepathology is the process of diagnostic histopathology performed on digital images viewed on a display screen rather than by conventional glass slide light microscopy. The technology of telepathology has radically improved over the past 5 years so that it is no longer the limiting factor in the diagnostic process. This review looks at the resources needed for dynamic and static telepathology, including image quality, computers and software interfaces, means of transmission and human resources. It critically analyses 32 published trials of telepathology, including some large prospective studies, in all areas of diagnostic histopathology including intraoperative frozen sections, routine and referral cases. New developments, including internet solutions and virtual microscopy, are described and there is analysis of the economics of telepathology within health care systems. The review concludes that all the necessary technology for telepathology is available, there is strong published evidence for a diagnostic accuracy comparable with glass slide diagnosis, in many contexts there is a clear-cut economic argument in favour of telepathology, and that the technique should now be integrated into mainstream diagnostic histopathology.

Does delay in fixation affect the number of mitotic figures in processed tissue?

The effect of delay in fixation on the number of mitotic figures in tissues has received little attention, and previous studies have reached differing conclusions. The numbers of mitotic figures in the normal mucosa of six colectomy specimens were counted with delays in fixation of 30 minutes, one hour, two hours, three hours and six hours for samples from each specimen. The numbers of mitotic figures were counted in 50 whole crypts in each specimen by two observers. All phases of mitosis were counted. The number of observable mitotic figures declined by about 30% with a delay in fixation of two hours and by 50% with a delay of six hours. This observation has important implications for the handling of surgical specimens.

Reassessment of the rate of fixative diffusion

The diffusion of fixatives is slow. Early work using plasma gels and animal tissues showed the distance penetrated by a fixative to be a simple function of the fixation time but this relation has not been established in human tissues. The rates of diffusion into whole human spleens were measured for three primary fixatives over periods ranging from one to 25 days. A positive correlation was demonstrated between penetration distance (mm) and fixation time (hours). The diffusion rates were slower than those in previous studies. These results have possible implications for the handling of surgical specimens.

Clinicians and the coronial system: ability of clinicians to recognise reportable deaths

OBJECTIVE

To assess the ability of clinicians to recognise deaths which require referral to the coroner.

DESIGN

Postal questionnaire consisting of 16 fictitious case histories, 14 of which contained a clear indication for referral to the coroner.

SETTING

Large teaching hospital. Coroner's office.

SUBJECTS

200 clinicians from general medical and surgical firms and senior staff of the local coroner's office (two coroner's officers and the two deputy coroners).

MAIN OUTCOME MEASURES

Number of correct assessments on questionnaire.

RESULTS

The mean recognition score for the clinicians was 9.11 (range 3-14) with no difference between the clinical grades. All of the coroner's senior staff recorded maximum recognition scores of 16.

CONCLUSIONS

The study highlights several features of the coronial system which are poorly understood by clinicians and provides the basis for an initiative to improve the medicolegal education of all clinicians.

Clinical necropsy rates during the 1980s: the continued decline

The trends in necropsy rates during the 1980s in three groups of British teaching hospitals in Leicester, Manchester, and Sheffield were compared in a retrospective study. The clinical necropsy rates declined in all three cities: in Leicester, from 16 to 10 per cent; in Manchester, from 14 to 8 per cent; and in Sheffield from 18 to 11 per cent. The medico-legal and overall necropsy rates showed variable trends between the cities. Specific events and changes in organization during the review period were correlated with the changing trends. The observed trends emphasize the continued decline in clinical necropsy rates over the last decade and illustrate the importance of monitoring differential necropsy rates.

The effects of crossing porcine renal artery ostia with various endovascular stents

OBJECTIVES

To compare the effects of crossing renal artery ostia with various stents.

METHODS

The renal artery ostia of 24 large white pigs were covered with a Wallstent (nine ostia), a Palmaz stent (nine ostia) and a Memotherm stent (13 ostia). After an interval of 6-15 weeks, aortography, renal pressure and blood samples were performed and the pigs then sacrificed for histological examination.

RESULTS

Histological examination revealed an organised collagen matrix with endothelial cells covering the struts in contact with the aorta. This occurred with all stents but was most organised with the Wallstent. This matrix did not involve the renal artery ostia crossed by Wallstents, but in one Palmaz stent and in 12/13 Memotherm stents, a disorganised acellular matrix caused partial ostial occlusion. There was no mean fall in renal artery pressure but traces were damped in 8/13 cases of partial occlusion. There was a rise in serum creatinine in two cases using the Palmaz stent.

CONCLUSIONS

Covering renal arteries with the Wallstent appears to be safe in the short-term. Placement of stents with larger struts across renal arteries will require imaging methods, such as intravascular ultrasound (IVUS) to ensure that the ostia are not obstructed.

An immunohistochemical study of altered immunomodulatory molecule expression in head and neck squamous cell carcinoma

For the presentation of peptide antigens to cytotoxic CD8+ T lymphocytes of the immune system, the expression of human leukocyte antigen (HLA) class I molecules on the cell surface is necessary. There is increasing evidence that surface HLA class I antigen expression is altered in a variety of human tumours by either loss or down-regulation of these molecules, which may be a strategy for evasion of immunosurveillance by malignant cells. This study has examined the expression of HLA class I molecules in head and neck squamous cell carcinoma (HNSCC) specimens by immunohistochemistry, using a wide panel of antibodies directed against allele-specific as well as monomorphic determinants of these molecules. The expression of TAP proteins, HLA-DR and the co-stimulatory molecule ICAM-1 were also studied. In addition, the expression of the tumour-associated antigens (TAA) p53 and MAGE genes was determined. Aberrant allelic expression of HLA class I antigens was detected in 17 out of 34 (50%) of the specimens stained, whereas HLA class I expression determined by W6/32 staining was found to be heterogeneous in only 2 out of 34 (6%) cases. Decreased expression of ICAM-1 was observed in 12 out of 34 (35%) tumour specimens and de novo expression of HLA-DR (HLA class II) by carcinoma cells in 13 out of 34 (38%) cases. Aberrant expression of HLA class I antigens was frequently observed in cases in which MAGE genes and p53 overexpression were detected. The altered expression of these immunomodulatory molecules in HNSCC may affect prognosis and has important implications for peptide-based immunotherapy strategies for these patients.

Quantitation of the renal arterial tree by fractal analysis

To determine whether the renal arterial system has a fractal structure, the fractal dimension of renal angiograms from 52 necropsy cases was measured using an implementation of the box-counting method on an image analysis system. The method was validated using objects with known fractal dimensions. The method was accurate with errors of less than 1.5 per cent and reproducible with initial values within 1.2 per cent of the mean of ten sets of measurements (reliability coefficient 0.968, 95 per cent confidence limits 0.911-0.984). In the 36 satisfactory angiograms the mean fractal dimension was 1.61 (SD 0.06), which was significantly greater than the topological dimension of 1 (P < 0.0001), indicating that the renal arterial tree has a fractal structure. There was no significant relationship between age (P = 0.494), sex (P = 0.136), or systolic (P = 0.069) or diastolic (P = 0.990) blood pressure, but two congenitally abnormal kidneys (hypoplastic dysplasia and renal artery stenosis) had fractal dimensions at the lower end of the normal range (third percentile). Since the renal arterial tree has a fractal structure, Euclidean geometric measurements, such as area and boundary length, are invalid outside precisely defined conditions of magnification and resolution.

Is the grading of breast carcinomas affected by a delay in fixation?

The effect of delay in fixation on the modified Bloom and Richardson grade of eight breast carcinomas was investigated. Topologically shuffled samples of each tumour were immersed in fixative at times of 0.5, 2, 4, 6, 18 and 24 h after surgical removal. The grade of each tumour was assessed at delays of 0.5 and 6 h. The tubule formation and nuclear pleomorphism components of the grade showed no change with a delay in fixation of 6 h. The number of mitotic figures declined by a mean of 53% over the same period and this resulted in a decrease in the histological grade of one of the tumours. The implications of these findings for the handling of breast specimens in a diagnostic histopathological laboratory are discussed.

The use of digital imaging, video conferencing, and telepathology in histopathology: a national survey

AIMS

To undertake a large scale survey of histopathologists in the UK to determine the current infrastructure, training, and attitudes to digital pathology.

METHODS

A postal questionnaire was sent to 500 consultant histopathologists randomly selected from the membership of the Royal College of Pathologists in the UK.

RESULTS

There was a response rate of 47%. Sixty four per cent of respondents had a digital camera mounted on their microscope, but only 12% had any sort of telepathology equipment. Thirty per cent used digital images in electronic presentations at meetings at least once a year and only 24% had ever used telepathology in a diagnostic situation. Fifty nine per cent had received no training in digital imaging. Fifty eight per cent felt that the medicolegal implications of duty of care were a barrier to its use. A large proportion of pathologists (69%) were interested in using video conferencing for remote attendance at multidisciplinary team meetings.

CONCLUSIONS

There is a reasonable level of equipment and communications infrastructure among histopathologists in the UK but a very low level of training. There is resistance to the use of telepathology in the diagnostic context but enthusiasm for the use of video conferencing in multidisciplinary team meetings.

Delay in fixation does not affect the immunoreactivity of proliferating cell nuclear antigen (PCNA)

The effect of delayed fixation on the immunoreactivity of proliferating cell nuclear antigen (PCNA) was investigated using eight breast carcinomas. Topologically shuffled samples of each tumour were immersed in fixative at times of 0.5, 1, 2, 4, 6, 18, and 24 h after surgical removal. In addition to a PCNA index (percentage of positive cells per 1200 tumour cells), a semi-quantitative PCNA grading system was used, based on estimates of more than or less than 50 per cent of positive tumour cells at each time interval. The PCNA index of six tumours increased by a mean of 10 per cent with a fixation delay of 24 h. The PCNA grade of all eight tumours showed no change with delayed fixation.

Acp. Best practice no 155. Pathological investigation of deaths following surgery, anaesthesia, and medical procedures

The pathological investigation of deaths following surgery, anaesthesia, and medical procedures is discussed. The definition of "postoperative death" is examined and the classification of deaths following procedures detailed. The review of individual cases is described and the overall approach to necropsy and interpretation considered. There are specific sections dealing with the cardiovascular system (including air embolism, perioperative myocardial infarction, cardiac pacemakers, central venous catheters, cardiac surgery, heart valve replacement, angioplasty, and vascular surgery); respiratory system (postoperative pneumonia, pulmonary embolism, pneumothorax); central nervous system (dissection of cervical spinal cord), hepatobiliary and gastrointestinal system; musculoskeletal system; and head and neck region. Deaths associated with anaesthesia are classified and the specific problems of epidural anaesthesia and malignant hyperthermia discussed. The article concludes with a section on the recording of necropsy findings and their communication to clinicians and medicolegal authorities.

Factors which influence necropsy requests: a psychological approach

AIMS

To determine which factors influence a clinician's decision to request a necropsy.

METHODS

Patient age, confidence in premortem diagnosis, relatives' attitudes, and conditions of necropsy practice were combined factorially (two levels each) in separate medical and surgical questionnaires based on clinical case histories. The interactions between the factors were measured by a repeated measures factorial analysis of variance for each of the two clinical groups. The influence of the clinician's interest in necropsies on these interactions was also examined by a similar method.

RESULTS

Necropsies were more likely to be requested on young patients, when diagnostic confidence was low, and when relatives' attitudes were favourable. Conditions of necropsy practice did not affect the likelihood of a request and there was no apparent overall difference in necropsy requests between the two groups of clinicians. The "patient age" and "relatives" factors had less influence on the decision of the surgical group to request necropsy. This was attributed to the opportunity to "see for themselves" at operation and was supported by the finding that surgeons were very likely to request necropsies in the absence of surgical intervention. Clinicians from both groups with a high pre-existing interest in the necropsy were consistently more likely to request necropsies.

CONCLUSIONS

The "case history" based questionnaires successfully measured the relative influence of multiple factors in relation to the decision of clinicians to request a necropsy. These findings suggest that any attempt to reverse the decline in necropsy rates should focus on changing the clinician's perception of the value of the modern necropsy.

Ownership and uses of human tissue: does the Nuffield bioethics report accord with opinion of surgical inpatients?

OBJECTIVE

To compare opinion of surgical inpatients with the conclusions of the report of the Nuffield Council on Bioethics regarding the ownership and uses of human tissue.

DESIGN

Survey of results of questionnaires completed by patients.

SETTING

Large teaching hospital.

SUBJECTS

384 postoperative adult surgical patients.

RESULTS

There was strong support among patients for the use of tissues in medical education, research, and science with the exception of those tissues which may transmit disease to others. Few patients (39; 10%) believed that they retained ownership of tissue removed at surgery. Most believed that the tissue belonged to the hospital (103; 27%), to nobody (103; 27%), or to the laboratory (77; 20%). Most patients had not been given any information about the possible uses of their tissues after removal.

CONCLUSIONS

Surgical inpatients seem to endorse the conclusions of the Nuffield report regarding the ownership and uses of human tissue. The recommendations regarding patient information and consent procedures should be implemented at the earliest opportunity.

Assessment of specimen fixation in a surgical pathology service

The quality of specimen fixation was examined within a routine diagnostic histopathology service. For each specimen the adequacy of fixation was assessed and the transit time between operating theatre and the laboratory was measured. Preliminary fixation was found to be inadequate in 25% of specimens and some form of manipulation to assist fixation was required in 36% of specimens. The mean transit time was 22 (SD 10.7) hours. Specimen fixation and transport are additional factors to consider in quality assurance of histopathology.

Offline telepathology diagnosis of colorectal polyps: a study of interobserver agreement and comparison with glass slide diagnoses

BACKGROUND/AIMS

Technological advances have produced telepathology systems with high quality colour images and reasonable transmission times. Most applications of telepathology have centred on the remote diagnosis of frozen sections or remote real time expert opinions. This study investigates the reproducibility and accuracy of offline telepathology as a primary diagnostic medium for routine histopathology specimens.

METHODS

One hundred colorectal polyps (50 hyperplastic, 50 adenomatous) were presented in a randomised order to five histopathologists as offline images on a telepathology workstation. Six images of each case were used: the slide label, a low power scan of all material on the slide, and four higher magnification views. The times taken to prepare the images, and to make the diagnoses, were recorded. Interobserver agreement was measured with kappa statistics and compared with the glass slide diagnoses.

RESULTS

The kappa statistics for the interobserver agreement on the telepathology images lay in the range of 0.90-1.00, which is interpreted as excellent agreement, and were significantly higher than those for the glass slide diagnoses (range, 0.84-0.98; p = 0.001). The median time taken to capture the images for a case was 210 seconds. The median time taken to make a diagnosis from the telepathology images was five seconds, which was significantly shorter than for the glass slide diagnoses (median, 13 seconds; p < 0.0005).

CONCLUSIONS

Offline telepathology has the potential to be a primary diagnostic medium for routine histopathology with a high degree of reproducibility and short diagnosis times. Further studies are required to validate offline telepathology for different types of specimens and different operators of the image capture system.

Have declining clinical necropsy rates reduced the contribution of necropsy to medical research?

AIMS

To examine trends in necropsy based research output for a period of 27 years during which there has been a progressive decline in clinical necropsy rates.

METHODS

The numbers of necropsy based research papers published between 1966 and 1993 were determined using the CD-Plus Medline computed literature database.

RESULTS

The number of necropsy based research papers containing necropsy or a synonym in the title increased by 220% between 1966 and 1993. When papers including necropsy or a synonym in the abstract, but not in the title, were included, the proportion of all indexed papers increased from 0.35% in 1975, when abstracts were first included, to 0.53% in 1993. Analysis of the subject material indicated that necropsy based research has constantly reflected trends and advances in clinical medicine. Neuroscience related research represented the largest subject category which may reflect the difficulties in obtaining human tissue from sources other than necropsy.

CONCLUSIONS

The modern necropsy continues to provide valuable information for all clinical and laboratory based disciplines. The decline in clinical necropsy rates would not yet appear to have undermined the contribution of the necropsy to research.

Asking relatives for permission for a post mortem examination

This article discusses the possible aims, benefits, and also the content, format and timing of training in one specific aspect of clinical practice; how to request permission for post mortems.

Attitudes of senior pathologists towards the autopsy

The attitudes of 205 consultant British pathologists in four regions were assessed by a postal questionnaire in which they were asked to indicate their level of agreement with 15 statements relating to autopsies. A total of 144 pathologists completed the questionnaire (response rate 70 per cent). Senior pathologists strongly agreed with statements relating to the importance of autopsies within pathology workloads, medical audit, and accreditation for training posts. There was strong support for the attendance of clinicians at autopsy demonstrations and for the suggestion that material from medico-legal autopsies should be made available for teaching and research. There was strong disagreement with the suggestions that advances in diagnostic techniques have diminished the role of autopsies, that performing autopsies does not further pathologists' education, that the cost of autopsies may not be justifiable within a limited budget, and that the autopsy should no longer be part of the MRCPath examination. These results are discussed in the context of the current status of the autopsy in general.