ANATOMIC PATHOLOGY

 

Molecular autopsy method reveals genetic heart defect cause of young deaths

Cardiovascular News, 31 January 2007

Over one-third of young people who die suddenly without explanation may have a potentially heritable genetic arrhythmia defect, research from the US Mayo Clinic shows.

The investigators say that, using postmortem genetic testing,they have identified mutations known to cause Long QT Syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT) in 35% of such cases.

Both syndromes can cause sudden death without leaving structural or physical clues that can be detected by conventional autopsy methods.

"The fact that conventional autopsy fails to provide an answer is, in fact, a key clue that the killer may be LQTS or CPVT," noted senior author Michael Ackerman, who is head of the Clinic's Windland Smith Rice Sudden Death Genomics Laboratory, in Rochester, Minnesota.

Ackerman and co-investigator David Tester, also from Mayo Clinic, conducted comprehensive post-mortem LQTS genetic testing in 49 cases of sudden unexplained death that occurred at an average age of 14 years.

The researchers identified ten LQTS-associated mutations, four of which were novel, in ten (20%) cases.

In addition, they had previously reported from the same series that 15% of cases harbored mutations that confer susceptibility to CPVT, meaning 17 (35%) of the cases overall had a cardiac channel mutation.

"To prevent further tragic, premature deaths, the standard of care for the evaluation of sudden unexplained death must now change," said Ackerman.

"Surviving members in a family in which there's been this tragedy should receive medical attention that is equal to a 'full-court press'," he continued. "It must involve a careful and sleuth-like search for these inherited glitches in the heart's electrical system."

Ackerman added that families should now know that they can do more if the coroner or medical examiner cannot provide an explanation for a loved one's death.

"Postmortem genetic testing could be performed on the victim of sudden death in search of the cause," he stated. "Now, one-third of the time, we can find the cause."

 J Am Coll Cardiol 2007; 49: 240-246

 

 

Distribution of HPV genotypes in 282 women with cervical lesions: evidence for three categories of intraepithelial lesions based on morphology and HPV type

Rosemary E Zuna, Richard A Allen, William E Moore et al

Previously authors found differences in the distribution of the individual human papillomavirus types in cervical cancers and high-grade squamous intraepithelial lesions. This suggested that there were differences in risk for progression of high-grade squamous intraepithelial lesions that were related to human papillomavirus type within the category of oncogenic genotypes. In this work, we add additional cases including low-grade squamous intraepithelial lesions. ThinPrep^® samples from 282 squamous intraepithelial lesions and invasive cervical cancers were categorized morphologically by consensus interpretation and genotyped for 27 individual human papillomavirus types by polymerase chain reaction-based reverse line blot analysis using PGMY09/PGMY11 consensus primers for the L1 open reading frame. The 27 human papillomavirus types were divided into three categories: high risk 16, 18, 31, 45; intermediate risk 33, 35, 39, 51, 52, 56, 58, 59, 68, 73, 82, 83; and low risk: 6, 11, 26, 40, 42, 53, 54, 55, 57, 66, and 84. Of the 282 cases of cancer and squamous intraepithelial lesions, 95.7% were positive for one or more of 27 human papillomavirus types and 38.7% had two or more genotypes. Three major categories of squamous intraepithelial lesions were identified based upon the combination of consensus diagnosis and human papillomavirus category: (1) high-grade squamous intraepithelial lesions associated with high-risk human papillomavirus types that appear to be at increased risk for progression to carcinoma; (2) squamous intraepithelial lesions (typically low-grade intraepithelial lesions and high-grade lesions consistent with moderate dysplasia) associated with intermediate risk human papillomavirus types with limited or indeterminate risk for progression; (3) low-grade squamous intraepithelial lesions associated with low-risk human papillomavirus types with little or no risk for progression. Only a subset of human papillomavirus genotypes commonly considered to be oncogenic were closely associated with invasive cervical cancer and high-grade squamous intraepithelial lesions classed as severe dysplasia. Other oncogenic types were closely associated with high-grade squamous intraepithelial lesions of moderate dysplasia and low-grade squamous intraepithelial lesions. This suggests that risk for progression to invasion in squamous intraepithelial lesions is closely related to human papillomavirus genotype. Knowledge of the associated human papillomavirus type in women with morphologic squamous intraepithelial lesions may help to clarify risk for progression.

Modern Pathology (2007) 20, 167–174. doi:10.1038/modpathol.3800723; published online 22 December 2006

 

Simple Test Differentiates GIST From Leiomyosarcoma

Zosia Chustecka

February 13, 2007 — A simple new test can differentiate between gastrointestinal stromal tumor (GIST) and leiomyosarcoma (LMS), 2 nearly identical cancers that require radically different courses of treatment. The new test is based on just 2 genes but is more accurate than currently used tests involving immunostaining.

Developed by researchers at the University of Texas MD Anderson Cancer Center, in Houston, working in collaboration with the Institute for Systems Biology, in Seattle, Washington, the test is described in a paper published online February 13 in the Proceedings of the National Academy of Sciences.

"We hope that the test will be commercially available in about 6 to 12 months," Jonathan Trent, MD, PhD, from sarcoma center at MD Andersen, told Medscape in an interview. "In the meantime, clinicians can send samples to us for testing."

Misdiagnosis Can Mean Difference Between Life and Death

Although these are rare tumors, the implications for a misdiagnosis can be grave, Dr. Trent commented: "It can mean the mean the difference between life and death, because the diseases are treated so drastically differently." GIST and LMS are very similar tumors, both originating in the smooth-muscle cells of the gastrointestinal tract, and can be indistinguishable microscopically. But they are treated in radically different ways, Dr. Trent continued. GIST responds very well to treatment with the selective tyrosine kinase inhibitor imatinib (Gleevec, Novartis), with responses in up to 80% of cases, whereas LMS is treated with chemotherapy, with responses in up to 60% of cases or more. "But the opposite is not true — GIST does not respond at all to chemotherapy and LMS does not respond at all to imatinib." Hence, the consequences of a misdiagnosis can be devastating: "If you misdiagnosed someone with GIST as having LMS and treated them with chemotherapy, it almost certainly would not work to shrink their tumor, and it almost certainly would result in significant toxicity without any benefit."

At present, differentiation between the tumors is made by KIT immunostaining, but this is subjective and variable due to cellular heterogeneity that may result in false-negative diagnoses, the researchers comment in their paper. It is about 87% accurate, but uncertain cases require further intensive and time-consuming additional analyses.

"KIT immunostaining is not a great test to distinguish the 2," Dr. Trent commented. "It's very subjective, and KIT can be expressed by both types of tumors, leading to false-positive results."

"The new test is an improvement, it's quantitative rather than subjective, and so far it looks to be close to 100% accurate," Dr. Trent commented. It is based on 2 genes. If the gene OBSCN expresses more of its RNA than the gene C9orf65, the tumor is GIST. If it's the other way around, the tumor is LMS.

"This is very novel methodology," Dr. Trent commented. The team used a process knows as top-scoring-pair analysis to look at pairs of genes, instead of the more common multiple-gene approach that has been used in other systems. "We looked at 41,000 genes in all possible combinations, and we were hoping to narrow it down to about 4 to 8 genes that were relevant — but, amazingly, we found that we needed only 2 genes."

When the researches applied the test to microarray data of 68 well-characterized GIST and LMS samples, the test successfully identified 67 of the 68 samples (97.8% accuracy). The exception was 1 tumor that showed a nearly 50-50 split between the 2 genes, the researchers report.

They repeated the trial in 20 of the microarray samples (including the sample that showed a near-equal split in gene expression) but this time used a more accurate measurement procedure on the 2 genes: this time the test correctly identified 20 of the 20 samples (100% accuracy).

In addition, the researchers carried out a further trial in 19 additional independent tumor samples that had not been included in the microarray data. "This is the most important test of our classifier," the researchers comment, before reporting that their test correctly identified all 19 tumors (14 GIST and 5 LMS).

"Thus, the 2-gene classifier chosen has yet to fail on any sample we have chosen," the researchers comment. "Of course, this does not mean that we can expect the classifier to perform perfectly on all future cases, but based on the evidence accumulated to date, there is a strong expectation of high accuracy."

Proc Natl Acad Sci. Published online February 13, 2007.

 

Myointimoma of the glans penis

Vardar E, Gunlusoy B, Arslan M, Kececi S.

Myointimoma is a recently described benign tumor, which is regarded as a rare type of mesenchymal tumor of the penis. The present patient was a 50-year-old man who had a nodule located in the glans penis. He had a 2 month history of a mass. An excisional biopsy was performed. The histological findings revealed a multinodular tumor that was characterized by spindle-shaped cells located in the intravascular area. This case, in addition to 11 cases reported in the literature, demonstrates that the myointimoma is frequently misdiagnosed on clinical and pathological grounds because of its rarity. Histological and immunohistochemical features are summarized on the basis of the present case and previously published reports.

Pathol Int. 2007 Mar;57(3):158-61

 

Measuring Errors in Surgical Pathology in Real-Life Practice: Defining What Does and Does Not Matter

Andrew A. Renshaw and Edwin W. Gould

This review summarizes our experience using blinded review as a method to measure quality in surgical pathology. It details the specifics about how the review is performed, the weaknesses in the method, and then summarizes our results so far. These results suggest that error rates correlate with the individual pathologist, the type of specimen, the type of diagnosis, subspecialization, and the number of pathologists who review a case. Errors do not correlate with workload.

This method is relatively unbiased and effective at identifying significant errors in real life clinical practice. The drawback to this method is the amount of work involved. Blinded review, performed so that errors can be corrected in a timely manner, and eventually integrated into an interlaboratory review process, represents a realistic and fair method to provide quantitative quality assurance information.

 

American Journal of Clinical Pathology, Volume 127, Number 1 / January 2007, pp. 144 - 152

 

 

Diagnostic error in anatomical pathology: the uncertainty of its measurement?

 S. J. BRYANT AND D. J. DAVIES

 Life is short, and Art long; the crisis fleeting; experience perilous, and decision difficult. The physician must not only be prepared to do what is right himself, but also to make the patient, the attendants, and externals cooperate. Hippocrates 400 BC.

It might be supposed that by the beginning of the 21st century AD much had changed in medicine since the time of Hippocrates, but in a recent British Medical Journal ‘Editor’s choice’ Godlee refers to the paradox of 20th century medicine outlined by Porter in The Cambridge History of Medicine that: ‘better health and longer life have been accompanied by ever greater medical anxieties… power and effectiveness have brought unrealistic expectations, critical scrutiny, distrust and loss of direction.  These remarks are relevant to the article ‘Diagnostic errors in anatomical pathology’ in this issue of Pathology.

 Coherent investigation and discussion of this topic is hampered by a lack of agreement about what constitutes ‘diagnostic error’ in anatomical pathology. It is important not to take the term at face value but to examine exactly what is under scrutiny. However, a recent review on quality in surgical pathology provides a useful frame of reference for classification of errors and adverse events. 

While histopathology differs in several ways from other types of laboratory testing, separating adverse events into ‘pre-analytical, post analytical and analytical’ is useful. Among the most serious of pre-analytical errors is defective identification which may have catastrophic effects on the patient. This risk is likely to be greatest in high throughput facilities sequentially generating multiple virtually indistinguishable specimens. Unrepresentative sampling when collecting the specimen from the patient or when selecting tissue for microscopic examination in the laboratory is another and may be recognised only with difficulty. Also inadequacy of the clinical history can impact upon the accuracy and completeness of pathology reports. Post-analytical defects are often typographical but inadvertent omission of negatives (‘no’ or ‘not’) can pose a risk; choice of terminology such as ‘absent’ in preference to ‘not present’ may obviate this. A particular hazard arises when an updated definitive report is generated to replace either an interim report or a previous ‘final’ report which has required amendment.  

The analytical phase of diagnostic histopathology contains several elements; some are essential and others optional (e.g., immunohistochemistry). In broad terms they can be divided into ‘technical’ and ‘diagnostic’ elements. The former are regarded as the province of the scientific and technical staff and the latter of the histopathologist, although substandard technical performance can affect the quality of the diagnostic opinion.  

It is the diagnostic component of histopathology, however, which is the principal focus of articles on diagnostic error in histopathology. Conventionally the elements among these which receive attention are the timeliness of the report and its completeness, but most critical is its ‘accuracy and precision’. ‘Accuracy’ is generally taken to be the extent to which the test result reflects a value obtained with a validated reference standard and ‘precision’ the extent to which observations on the same material can be consistently replicated on the same material. Both concepts are difficult to apply in anatomical pathology. However, medical laboratory testing is now beginning to embrace the concept of uncertainty measurement. While derived from arcane concepts of metrology, the International Bureau of Weights and Measures (BIPM) comments that: ‘human health depends critically on the ability to make accurate diagnosis and in which reliable measurement is increasingly important.’ Intrinsic to this is the concept of measurement uncertainty. This idea now has been introduced into medical testing in Australia. However, while this applies to testing which involves exact scientific measurements, the concept has yet to be applied to anatomical pathology. This does not mean that uncertainty does not exist in this area, just that no methods exist which recognise it, yet alone measure it. By default histopathology is currently practised in an environment where there is an expectation that its results consistently and invariably are the absolute truth. This may be due to unrealistic expectations on the part of medical administrations and medical colleagues but histopathologists may also have to reflect on whether they have contributed to this state of affairs.  

To improve understanding of the uncertainty of histopathological diagnosis it is important to reach an agreement about the nature of its different perceived defects and to determine their prevalence. Currently many reports cite rates for major and minor errors and whether or not they have a significant clinical impact. The Royal College of Pathologists in the United Kingdom in its document ‘Conducting a histopathology/cytopathology duty-of-care review: Guidance for trusts, reviewers and pathologists’ recommends that reviewers should classify any errors or discrepancies as:

Category 1: a diagnostic error, which would have a definite influence on clinical management and possible outcome.

Category 2: a diagnostic misinterpretation or oversight, which has the potential to affect clinical management or outcome.

Category 3: a minor discrepancy of disease categorisation likely to be of little clinical significance.

While from a perspective of safety and quality of care this categorisation is appropriate, it has limitations for the understanding of the intrinsic nature of the ‘causal cognitive error’ and the resultant outcome category to which such an error is assigned could be a matter of chance, depending on the circumstances of the case.

In histopathology the essential initial step is the acquisition of visual information from all of the material submitted, a task which is easier in some cases than others because of the nature of the material. However, the opinion is a judgment of that information in the context of all other information available to the pathologist interpreted against his or her knowledge and experience. This process is illustrated by the example cited in the article in this issue where a judgment was made that in a bronchial biopsy the quantity of abnormal tissue present was insufficient to reach a certain diagnosis of non-small cell carcinoma. Thus, in establishing the prevalence of ‘error’ in diagnostic histopathology there are limitations in determining the nature of the extent and gravity of the alleged defective performance, although on the balance of probability if the total number of cases surveyed is adequate, a high proportion of category 1 events makes substandard performance more likely than if they are predominantly category .

Allowing for this difficulty with definition, it is not surprising that reported surgical pathology error rates range from 0.25 to 40.0% in North America, although there is some agreement that a ‘significant’ error is in the range of 0.5 to 1.0%. In the United Kingdom, a consensus emerging from a system running for 7 years from1988 was that error would occur in roughly 3–4% of cases and that those likely to affect patient management involve between 1.0 and 1.5% of cases. On this basis the error rates attributed to a locum histopathologist of 14% and 9% would certainly seem to be high. However, error rates within the standard range can still occur even among subspecialty groups and instances of failure among experts to achieve consensus is well recognised. While some areas of particular diagnostic difficulty are well recognised, including pigmented skin tumours and malignant lymphoma, ‘errors’ most often occur with common specimen types; this study also observed that there were pathologists whose performance using the method of their study had a result which was ‘considered aberrant, although not necessarily incorrect’.

Against this background, the investigation of alleged diagnostic error by a histopathologist should not be undertaken lightly. While primarily an issue for the employing authority, this should be commenced only after seeking advice from the relevant professional body and probably also of the medical board in the jurisdiction concerned. In the United Kingdom the Royal College of Pathologists has published two documents: ‘Conducting a histopathology/cytopathology duty-of-care review: guidance for trusts, reviewers and pathologists’ and ‘Substandard performance in pathology: guidance for NHS Trusts and pathologists’. The latter notes that identification of interpretative errors is problematic and can be considered only in the full clinical context. It provides a template for performance assessment requiring that it must be fair, objective and transparent using a range of valid and acceptable criteria but no particular method is delineated. In this document, the Royal College of Pathologists accepts a significant clinical reporting error rate of 1–2%. A systematic review of histopathology is not regarded as a reliable way of assessing an individual’s performance, being time consuming and costly. If an individual’s performance by a review with the College’s criteria is judged substandard then a systematic review of the work may be commissioned by the employing Trust as part of that Trust’s duty of care. This should be separate from a performance review. While not extensively publicised, the Royal College of Pathologists of Australasia (RCPA) has had since 2001 in its Policy Manual an Executive Determination ‘Procedure for investigation of allegations of poor professional performance in anatomical pathology (histopathology and cytopathology)’ which includes a process of ‘blind review’ of cases. This is accessible from the RCPA Members’ Document Library (www.rcpa.edu.au) and available to employing authorities when concerns are raised over potential poor performance of an anatomical pathologist.

In discussing what needs to be done, Leong et al. observe that, compared with other medical disciplines, pathologists are far advanced with measures to minimise errors, although in view of information available there are no grounds for complacency. To be prepared ‘to do what is right himself’ pathologists must continue to engage in an internal audit of their diagnostic activities within their practice as well as participating in external quality assurance. If the individual is an isolated practitioner, he or she should arrange a relationship with an appropriate peer group for this purpose but also for advice and support; while they should take the initiative this should be facilitated by employers. Also excessive expectations of histopathological diagnosis should not be promoted, particularly from small and possibly unrepresentative tissue samples. The pathologist should be prudent and avoid advancing opinions beyond those that can be reasonably adduced for the specimen submitted and such other information (if any) which has been provided. While in histopathology the patient can be exculpated from a contribution to its problems, there is much which could be done ‘to make..the attendants, and externals cooperate’. There must be an increased understanding of ‘uncertainty measurement’ in histopathology to diminish unrealistic expectations, the work environment must be such as to avoid exposure of a pathologist to excessive demands both in terms of volume of the work and the level of expertise demanded, e.g., by a sole pathologist in a rural centre being expected to meet, without any additional training or other resources, the pathology needs of visiting city specialists. There is no single ‘magic’ solution such as ‘double reading’ of every slide with a neoplastic diagnosis. A comprehensive approach to maximising the quality of performance by sufficient investment in infrastructure and staff is likely to be the best approach to reduction of errors in histopathology, diagnostic and other.  

Pathology (December 2006) 38(6), pp. 487–489

CLINICAL PATHOLOGY

 

Blood Separation Technique Suitable for Doctor’s Office

 

A process for rapidly and efficiently separating blood plasma at the microscopic level without any moving parts allows doctors to do blood tests without sending samples to a laboratory. The new method uses the same principle that causes tea leaves to accumulate at the center of the bottom in a stirred teacup, a phenomenon first explained by Einstein in the 1920s.

Separating blood plasma from red blood cells, proteins, and other microscopic particles is an essential step in many common medical tests, including those for cholesterol levels, drugs in athletes, blood types in donors, and glucose levels in diabetics. Current testing requires samples to be taken in a doctor's office and sent off to a laboratory and analyzed with a large centrifuge, a process that can take several days.

In the new method, a tiny amount of blood enters a fluid chamber, and a needle tip is placed close to the surface of the blood at an angle. A voltage is applied to the needle, generating ions around its tip that repel the oppositely charged ions close to it. This creates an airflow known as "ionic wind," which sweeps across the surface of the blood, causing it to circulate. The microscopic particles in the blood travel in a downward spiral because of the needle's angle relative to the surface.

When the fluid begins to circulate, one might intuitively expect the microscopic particles such as red blood cells would be pulled to the outside wall of the chamber owing to centrifugal force. But because of a phenomenon called the "tea leaf paradox," the particles are instead pulled inward near the bottom of the chamber. The tiny chamber of blood, like the teacup, is a cylinder of liquid that is rotated at the top while the base remains stationary. To satisfy a zero-velocity condition at the base, an inward force near the bottom of the liquid is generated, suppressing the centrifugal force there. The microscopic particles spiral inward toward the bottom of the chamber like a miniature tornado, leaving a clear layer of plasma above.

The method was developed by Drs. Dian R. Arifin, Leslie Y. Yeo, and James R. Friend, from Monash University's (Melbourne, Australia) micro/nanophysics research laboratory in the department of mechanical engineering. Dr. Yeo anticipates that the technology could be incorporated into a chip roughly the size of a credit card. He said the devices could be produced cheaply with current manufacturing techniques - about 50 cents per chip - but could still be five to 10 years away from mass production.

By medinews.com staff writers

Posted on 12 February 200712 February 2007

BOTTOM LINE

Medical Milestones

From 5-14 January 2007, editors of the Student BMJ conducted an online poll to decide the most important medical advance since 1840. From a list initially suggested by our readers, an expert panel chose the top 15, which formed the basis for the vote. We also published a supplement, where champions argued the merits of each individual advance.

Sanitation emerged as the winner.

Watch the webcast announcing the result

 Results of poll 

Most important advance
	Number	Proportion (%)
Anaesthesia	1574	13.9
Antibiotics	1642	14.5
Chlorpromazine	73	0.6
Computers	405	3.6
Discovery of DNA structure	1000	8.8
Evidence-based medicine	636	5.6
Germ theory	843	7.4
Immunology	182	1.6
Medical imaging (x-rays, etc.)	471	4.2
Oral contraceptive pill	842	7.4
Oral rehydration therapy	308	2.7
Risks of smoking	183	1.6
Sanitation (clean water and sewage disposal)	1795	15.8
Tissue culture	50	0.4
Vaccines	1337	11.8
Total Respondents	11341	100.0

 

 

Visitor category
	Number	Proportion (%)
Doctor	3198	28.6
Nurse/midwife	330	3.0
Other healthcare professional	677	6.1
Academic researcher	1144	10.2
Public health/Health policy	487	4.4
Student	1582	14.2
Librarian/Information specialist	188	1.7
Education	462	4.1
Industry	437	3.9
Member of the public	2438	21.8
Press/media	220	2.0
Total Respondents	11163	100.0

 

Country
	Number	Proportion (%)
Australia	315	2.8
Bulgaria	573	5.0
Canada	604	5.3
Germany	200	1.8
India	256	2.3
Italy	547	4.8
Spain	324	2.8
United Kingdom	4281	37.7
United States	2270	20.0
Other countries	1992	17.5
Total respondents	11362	100.0