Histological examination in sudden unexpected death in infancy: evidence base for histological sampling

AIM

Pathologists currently follow the 'Kennedy guidelines' when performing autopsies for sudden unexpected death in infancy (SUDI); these include extensive histological sampling. This study establishes the frequency with which histological examination of visceral organs determines cause of death and examines associations between clinical, macroscopic and microscopic findings.

METHODS

Retrospective review of 546 SUDI autopsies performed for a 10-year period (1996-2005) at a single centre. The proportion of cases in which non-neuropathological histological examination directly determined the cause of death was identified, and clinical, macroscopic and histological findings at autopsy were compared.

RESULTS

Of 510 SUDIs included, 166 cases were explained SUDI, and of these, 54% (89/166) were identified solely on microscopic examination, based on histology of the lungs in 71 (43%), heart in 13 (8%), liver in 4 (2%) and kidneys in 1 (<1%). The proportions of macroscopically normal organs with significant histological findings were 26% lungs, 2% heart and 1% each of liver and kidneys, but none of spleen, thymus, pancreas or adrenals. Macroscopically abnormal organs were more likely to yield significant histological features. Symptoms preceding death were more common in cases with significant histological findings in lungs, heart, liver and adrenals.

CONCLUSION

A non-neuropathological cause of death in explained SUDI can be established from histological examination of lungs, heart, liver and kidneys. Significant histological abnormalities may be detected in selected organs with macroscopically normal appearances. Routine histological sampling of other organs in the absence of specific clinical history or macroscopic abnormalities has a low yield for establishing cause of death.

Tandem mass spectrometry findings at autopsy for detection of metabolic disease in infant deaths: postmortem changes and confounding factors

AIM

Tandem mass spectrometry (MS/MS) is a recommended investigation for sudden unexpected death in infancy (SUDI), but there are limited data regarding yield and potential influencing factors. This study investigates postmortem acylcarnitine profiles in a large cohort of infant deaths from a single centre, including those with metabolic disease.

METHODS

Acylcarnitine results obtained by MS/MS from routine blood/bile spot samples during the standard autopsy investigation were identified from infant deaths over a 14-year period. Results were categorised as normal or abnormal according to the clinical report by a specialist paediatric biochemist. Possible interdependent variables were assessed, multiple linear regression models were constructed and residual comparison was undertaken.

RESULTS

397 blood and 268 bile MS/MS results were identified from infant cases, including 255 matched blood-bile pairs. There was significant association between blood acylcarnitine findings and postmortem interval (PMI), body mass index and liver weight. A probable cause of death was identified in 40% of sudden death cases, including 18 (2%) with a definite or highly likely cause of death as underlying metabolic disease; this represented 12 (12%) unexpected deaths in the first week of life and six (<1%) aged 7-365 days. Fatty acid oxidation disorders identified included very long chain acyl-CoA dehydrogenase deficiency, medium chain acyl-CoA dehydrogenase deficiency and carnitine transporter defects.

CONCLUSION

Postmortem blood and bile acylcarnitine profiles are influenced by several variables, and PMI can influence MS/MS acylcarnitine results. Metabolic disease may present as SUDI and may be identified from postmortem samples.

[Symptomatic bilateral soft tissue tumor of the breast wall]

A 54-year-old woman presented with progressive swelling of the right scapula as well as motion-dependent pain. The medical history revealed a polyglandular autoimmune syndrome and lumbar disc degeneration. The magnetic resonance imaging (MRI) scan showed a bilateral well-defined muscle isointense space-occupying lesion situated between the scapula, rib cage and thoracic muscles with homogeneous contrast enhancement. The constellation is indicative of a elastofibroma dorsi, a rare mesenchymal tumor often appearing bilaterally.

Virological investigations in sudden unexpected deaths in infancy (SUDI)

Previous studies have implicated viral infections in the pathogenesis of sudden unexpected death in infancy (SUDI), and routine virological investigations are recommended by current SUDI autopsy protocols. The aim of this study is to determine the role of post-mortem virology in establishing a cause of death. A retrospective review of 546 SUDI autopsies was carried out as part of a larger series of >1,500 consecutive paediatric autopsies performed over a 10-year period, 1996-2005, in a single specialist centre. Virological tests were performed as part of the post-mortem examination in 490 (90%) of the 546 SUDI autopsies, comprising 4,639 individual virological tests, of which 79% were performed on lung tissue samples. Diagnostic methods included immunofluorescence assays (using a routine respiratory virus panel; 98% of cases), cell culture (61%), rapid culture techniques such as the DEAFF test for CMV (55%), PCR (13%), electron microscopy (10%), and others. Virus was identified in only 18 cases (4%), viz. five cases of enterovirus, four of RSV, three of HSV and CMV, and one each of adenovirus, influenza virus and HIV. In seven of the 18 cases the death was classified as due to viral infection, whilst of the remaining 11 cases, death was due to bacterial infection in five, a non-infective cause in one and unexplained in five. Virus was identified in 33% of deaths due to probable viral infections, but also in 6% of SUDI due to bacterial infections, and in 2% of SUDI due to known non-infective causes and unexplained SUDI. When predominantly using immunofluorescence, virus is identified in only a small proportion of SUDI autopsies, resulting in a contribution to the final cause of death in <2% of SUDI post-mortem examinations. Routine post-mortem virological analysis by means of an immunofluorescence respiratory virus panel appears to be of limited benefit in SUDI for the purposes of determining cause of death. Application of a broader panel using more sensitive detection techniques may reveal more viruses, although their contribution to the final cause of death requires further exploration.

[Invasive diagnostic procedures for insulinomas of the pancreas]

Insulinomas are the most common cause for hypoglycemia with endogenous hyperinsulinism. Insulinomas are the most frequent endocrine tumor of the pancreas and 10% occur as multiple tumors (e.g. multiple endocrine neoplasia type I) or in rare cases as islet cell hyperplasia. A further 10-15% of insulinomas are malignant. Non-invasive imaging modalities, such as computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US) and somatoreceptor scintigraphy (SRN) show a lower sensitivity for detection and localization of tumors, because in many cases insulinomas are smaller than 2 cm in size. Invasive pre-operative diagnostic procedures, such as transhepatic peripancreatic venous blood sampling (TPVB) and the intra-arterial calcium stimulation test (ASVS) are much more time-intensive compared to CT, MRI and US with an examination time of 2-3 h but achieve a more exact pre-operative detection and localization with sensitivities mostly greater than 95% and are therefore the diagnostic methods of choice.

Prospective parental consent for autopsy research following sudden unexpected childhood deaths: a successful model

BACKGROUND

Organ retention issues, recent changes in the Coroners' (Amendment) Rules 2005 and the Human Tissue Act have resulted in pessimism regarding prospective consent for paediatric autopsy research in the UK.

OBJECTIVES

To examine the feasibility and acceptability of a prospective telephone consenting model for post-mortem magnetic resonance (MR) imaging research in HM Coroners' cases.

DESIGN

Following each autopsy referral from the HM Coroner, permission to contact the family for research was requested. A family liaison sister, with experience in dealing with bereaved families, then contacted the parents by telephone, explained the study and obtained oral, and then written consent for post-mortem imaging.

SETTING

London and an area south of London.

RESULTS

Of 76 eligible HM Coroners' cases referred during the study period, permission to contact parents (provided by the HM Coroners' Office) was obtained for only 32 cases (42%). The research sister contacted 32 parents during the study period of whom 31 (96.8%) gave oral research consent. "Helping other parents in the future" and "the importance of post-mortem research" were the main reasons for parents wanting to participate in research.

CONCLUSIONS

Prospective consenting for HM Coroners' cases for research is feasible in children, and can be done ethically by parental consenting via telephone contact before autopsy by appropriately trained staff. However, close co-ordination between mortuary staff, HM Coroners, research staff and medical staff is required. This model may be useful in performing post-mortem research in HM Coroners' cases and in developing paediatric tissue and brain banks in the UK.

The role of post-mortem investigations in determining the cause of sudden unexpected death in infancy

INTRODUCTION

Several autopsy protocols have been suggested for investigating sudden unexpected deaths in infancy (SUDI). The aim of this study is to provide data on the utility of such post-mortem investigations from a large paediatric autopsy series to inform future policy.

METHODS

Retrospective analysis of >1500 consecutive post-mortem examinations carried out by specialist paediatric pathologists at a single centre during a 10-year period according to a common autopsy protocol that included the use of detailed ancillary investigations. SUDI was defined as the sudden unexpected death of an infant aged from 7 to 365 days. All data capture and cause of death classification were carried out according to defined criteria.

RESULTS

Of 1516 paediatric post-mortem examinations, 546 presented as SUDI. In 202 infants (37%), death was explained by the autopsy findings. The other 344 cases (63%) remained unexplained. Of the explained deaths, over half (58%) were infective, most commonly due to pneumonia (22%). The component of the post-mortem examination that primarily determined the final cause of death was histological examination in 92 infants (46%), macroscopic examination in 61 (30%), microbiological investigations in 38 (19%) and clinical history in 10 (5%).

CONCLUSION

This constitutes the largest single-institution autopsy study of SUDI. Ten years on from the Confidential Enquiry into Stillbirths and Deaths in Infancy (CESDI) SUDI studies, the ascertainment of a cause of death at autopsy has improved. However, with almost two thirds of SUDI remaining unexplained, alternative and/or additional diagnostic techniques are required to improve detection rates of identifiable causes of death at autopsy.

Clinicopathological features of paediatric deaths due to myocarditis: an autopsy series

INTRODUCTION

Myocarditis is a recognised cause of cardiac failure in childhood but the frequency of myocarditis as a cause of sudden unexpected death across the paediatric age range is uncertain.

METHODS

A structured review of the results of all autopsies carried out in a single paediatric centre over a 10-year period, including the results of all investigations performed as part of the centre's policy for the post-mortem investigation of paediatric deaths.

RESULTS

During the study period there were 1516 autopsies of children aged 0-18 years. Histologically proven myocarditis was present in 28 cases (1.8%, age range 10 days to 16 years, median age 10 months), of which 16 (57%) presented as sudden death. More than half of all cases (54%) occurred in infants less than 1 year of age, accounting for 2% of infant deaths referred for autopsy, compared with around 5% of childhood deaths over the age of 5 years. In almost 40% of cases there were no macroscopic cardiac abnormalities, the diagnosis being entirely dependent on routine histological examination of the heart, and post-mortem heart weight was normal in the majority of cases. Virus was detected in nine (36%) of the 25 cases in whom virological analyses were performed. The histological features were similar in all cases, with an interstitial inflammatory cell infiltrate, predominantly lymphocytic, with focal myocyte necrosis and interstitial oedema.

CONCLUSIONS

Myocarditis is a rare cause of death in infancy and childhood, and the majority of cases present as sudden unexpected deaths, which require routine histological sampling of the heart for its detection.

Infection and sudden unexpected death in infancy: a systematic retrospective case review

BACKGROUND

The cause and mechanism of most cases of sudden unexpected death in infancy (SUDI) remain unknown, despite specialist autopsy examination. We reviewed autopsy results to determine whether infection was a cause of SUDI.

METHODS

We did a systematic retrospective case review of autopsies, done at one specialist centre between 1996 and 2005, of 546 infants (aged 7-365 days) who died suddenly and unexpectedly. Cases of SUDI were categorised as unexplained, explained with histological evidence of bacterial infection, or explained by non-infective causes. Microbial isolates gathered at autopsy were classified as non-pathogens, group 1 pathogens (organisms usually associated with an identifiable focus of infection), or group 2 pathogens (organisms known to cause septicaemia without an obvious focus of infection).

FINDINGS

Of 546 SUDI cases, 39 autopsies were excluded because of viral or pneumocystis infection or secondary bacterial infection after initial collapse and resuscitation. Bacteriological sampling was done in 470 (93%) of the remaining 507 autopsies. 2079 bacteriological samples were taken, of which 571 (27%) were sterile. Positive cultures yielded 2871 separate isolates, 484 (32%) of which showed pure growth and 1024 (68%) mixed growth. Significantly more isolates from infants whose deaths were explained by bacterial infection (78/322, 24%) and from those whose death was unexplained (440/2306, 19%) contained group 2 pathogens than did those from infants whose death was explained by a non-infective cause (27/243, 11%; difference 13.1%, 95% CI 6.9-19.2, p<0.0001 vs bacterial infection; and 8.0%, 3.2-11.8, p=0.001 vs unexplained). Significantly more cultures from infants whose deaths were unexplained contained Staphylococcus aureus (262/1628, 16%) or Escherichia coli (93/1628; 6%) than did those from infants whose deaths were of non-infective cause (S aureus: 19/211, 9%; difference 7.1%, 95% CI 2.2-10.8, p=0.005; E coli: 3/211, 1%, difference 4.3%, 1.5-5.9, p=0.003).

INTERPRETATION

Although many post-mortem bacteriological cultures in SUDI yield organisms, most seem to be unrelated to the cause of death. The high rate of detection of group 2 pathogens, particularly S aureus and E coli, in otherwise unexplained cases of SUDI suggests that these bacteria could be associated with this condition.

Pharmacokinetic analysis of malignant pleural mesothelioma-initial results of tumor microcirculation and its correlation to microvessel density (CD-34)

RATIONALE AND OBJECTIVES

Malignant mesothelioma (MM) of the pleura is an aggressive and often fatal neoplasm. Because MM frequently demonstrates marked angiogenesis, it may be responsive to antiangiogenic therapy, but effective methods for selecting and monitoring of patients are further needed. We employed dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and quantitative immunohistochemistry (IHC) to characterize the microvascularity of MM using both a physiologic and ultrastructural method.

MATERIALS AND METHODS

Nineteen patients diagnosed with MM were enrolled and DCE-MRI was performed before antiangiogenic treatment. For each patient, tumor regions were characterized by their DCE-MRI-derived pharmacokinetic parameters (Amp, k(ep), k(el)), which were also compared to those of normal tissue (aorta, liver, spleen, and muscle). In addition, quantitative IHC of representative samples was performed with CD-34 staining to compare the calculated microvessel density (MVD) results with DCE-MRI results.

RESULTS

MM demonstrated markedly abnormal pharmacokinetic properties compared with normal tissues. Among the parameters tested, Amp was significantly different in MM (P < or = .001) compared to normal organs. Despite the observation that the MVD of mesotheliomas in this series was high compared to other tumors, DCE-MRI pharmacokinetic parameters had a moderately positive correlation with MVD (r = 0.5).

CONCLUSIONS

DCE-MRI and IHC can be used in patients with MM to visualize tumor microvascularity and to characterize tumor heterogeneity. DCE-MRI and IHC results positively correlated, though moderately, but these two methods present as essential tumor biomarkers. This multimodal characterization may be useful in selecting possible tumor subtypes that would benefit from antiangiogenic therapy.

[Sellar tumors]

Because of the complex anatomy, examination of the sella turcica and hypophysis needs a dedicated MR sequence protocol. Not every sellar lesion is a pituitary adenoma. Thus, this review article summarizes the most frequently encountered intra-, supra-, and parasellar tumors and lesions. Differential diagnoses comprise besides adenoma among others craniopharyngioma, meningioma, glioma, germinoma, hamartoma, aneurysm, trigeminal schwannoma, pituitary carcinoma, chordoma, metastasis, infection, and empty sella. Characteristic imaging findings are presented and correlated to micro- and macro-pathology.

Treatment of microalbuminuria in hypertensive subjects with elevated cardiovascular risk: Results of the IMPROVE trial

Microalbuminuria independently predicts increased cardiovascular risk in hypertensive patients, especially in those with concomitant diabetes or established cardiovascular disease. Drugs that target the renin-angiotensin-aldosterone system reduce microalbuminuria regardless of diabetic status. The Irbesartan in the Management of PROteinuric patients at high risk for Vascular Events was a multicenter, randomized, double-blind, placebo-controlled paralleled group study in which hypertensive patients with microalbuminuria and increased cardiovascular risk were randomized to 20 weeks treatment with ramipril plus irbesartan or to ramipril plus placebo. Patients discontinued or tapered previous antihypertensive therapy during a 14-day placebo lead-in period. Change in albumin excretion rate from baseline to week 20 was the primary end point. Adjusted week 20 baseline geometric ratios for ramipril plus irbesartan and ramipril plus placebo were not significantly different. Although differences in blood pressure reductions were observed between the two treatments, these changes did not affect microalbuminuria. More patients on dual therapy achieved target blood pressure goals at week 20 than with monotherapy. The incidence of adverse effects and treatment-related adverse effects was similar in both groups. Our results suggest that patients with cardiovascular risk and relatively low albumin excretion rates in early-stage disease may only require monotherapy with renin-angiotensin-aldosterone blocking agents.

Challenges to implementation of the new Coroners' (Amendment) Rules 2005: experience from a tertiary paediatric pathology centre

In the UK sudden unexpected childhood deaths are referred to Her Majesty's Coroner (HMC) for postmortem examination during which small tissue samples are obtained for diagnostic purposes. Recent changes to regulate tissue use include the Coroners' (Amendment) Rules 2005. We audited the impact of these at a specialist paediatric centre. A retrospective audit of HMC tissue forms for autopsies was performed between 1 June 2005 - 31 May 2006, with regard to the options provided to, and chosen by, parents. Of 213 coronial autopsies, 178 were non-forensic. Tissue forms were submitted pre-autopsy in 25 (14%). An additional 47 were received after sending follow-up letters for a total of 72/178 (40%). Forms varied between coroners, but most failed to distinguish between blocks, slides, and other tissue samples and 6/40 (15%) forms did not specifically allow an option for research consent. Forty-three (60%) parents opted for retention, with 34 (79%) also consenting to research. Only six (8%) requested return of tissue. A simple, unified tissue disposal form and information sheet for all HMC districts, which includes appropriate options, would ensure that parents' wishes are met, to achieve best practice, maximise sample availability for positive societal outcomes such as teaching and research, and to comply with new regulations.

[Treatment options for arteriovenous malformations]

Cerebral arteriovenous malformations are errors in the development of vasculature with shunts between cerebral arteries and veins, which manifest predominantly as intracerebral hemorrhage. To prevent hemorrhage, a complete obliteration of the arteriovenous malformation is necessary. For this purpose, techniques of microsurgery, radiotherapy, and embolization alone or in combination are available. This review article presents the treatment options and also summarizes available data from the literature on which therapy should be chosen in which situation and when watchful waiting should be preferred.

Funktionelle Bildgebung bei Hirntumoren (Perfusion, DTI, MR-Spektroskopie)

This contribution considers the possibilities involved with using functional methods in magnetic resonance imaging (MRI) diagnostics for brain tumors. Of the functional methods available, we discuss perfusion MRI (PWI), diffusion MRI (DWI and DTI) and MR spectroscopy (H-MRS). In cases of brain tumor, PWI aids in grading and better differentiation in diagnostics as well as for pre-therapeutic planning. In addition, the course of treatment, both after chemo- as well as radiotherapy in combination with surgical treatment, can be optimized. PWI allows better estimates of biological activity and aggressiveness in low grade brain tumors, and in the case of WHO grade II astrocytoma showing anaplasically transformed tumor areas, allows more rapid visu-alization and a better prediction of the course of the disease than conventional MRI diagnostics. Diffusion MRI, due to the directional dependence of the diffusion, can illustrate the course and direction of the nerve fibers, as well as reconstructing the nerve tracts in the cerebrum, pons and cerebellum 3-dimensionally. Diffusion imaging can be used for describing brain tumors, for evaluating contralateral involvement and the course of the nerve fibers near the tumor. Due to its operator dependence, DTI based fiber tracking for defining risk structures is controversial. DWI can also not differentiate accurately between cystic and necrotic brain tumors, or between metastases and brain abscesses. H-MRS provides information on cell membrane metabolism, neuronal integrity and the function of neuronal structures, energy metabolism and the formation of tumors and brain tissue necroses. Diagnostic problems such as the differentiation between neoplastic and non-neoplastic lesions, grading cerebral glioma and distinguishing between primary brain tumors and metastases can be resolved. An additional contribution will discuss the control of the course of glial tumors after radiotherapy.

[Radiological diagnostics of muscle diseases]

Muscular diseases are a heterogeneous group of diseases with difficult differential diagnosis. This article reviews morphological and functional radiological techniques for assessment of muscular diseases. Morphological techniques can describe edema-like changes, lipomatous and atrophic changes of muscular tissue. However, these imaging signs are often not disease-specific. As a result, clinicians assign radiology a secondary role in the management of muscular diseases. Meanwhile, functional radiological techniques allow the assessment of muscle fiber architecture, skeletal muscle perfusion, myocellular sodium-homoeostasis, lipid- and energy-phosphate metabolism, etc. By detecting and spatially localizing pathophysiological phenomena, these new techniques can increase the role of radiology in muscular diseases.