Muscle biopsies in children--an evaluation of histopathology and clinical value during a 5-year period

Fine-needle percutaneous muscle microbiopsy technique as a feasible tool to address histological analysis in young children with cerebral palsy and age-matched typically developing children

Cerebral palsy (CP) is a heterogeneous group of motor disorders attributed to a non-progressive lesion in the developing brain. Knowledge on skeletal muscle properties is important to understand the impact of CP and treatment but data at the microscopic levels are limited and inconsistent. Currently, muscle biopsies are collected during surgery and are restricted to CP eligible for such treatment or they may refer to another muscle or older children in typically developing (TD) biopsies. A minimally invasive technique to collect (repeated) muscle biopsies in young CP and TD children is needed to provide insights into the early muscle microscopic alterations and their evolution in CP. This paper describes the protocol used to 1) collect microbiopsies of the medial gastrocnemius (MG) and semitendinosus (ST) in CP children and age-matched TD children, 2) handle the biopsies for histology, 3) stain the biopsies to address muscle structure (Hematoxylin & Eosin), fiber size and proportion (myosin heavy chain), counting of the satellite cells (Pax7) and capillaries (CD31). Technique feasibility and safety as well as staining feasibility and measure accuracy were evaluated. Two microbiopsies per muscle were collected in 56 CP (5.8±1.1 yr) and 32 TD (6±1.1 yr) children using ultrasound-guided percutaneous microbiopsy technique. The biopsy procedure was safe (absence of complications) and well tolerated (Score pain using Wong-Baker faces). Cross-sectionally orientated fibers were found in 86% (CP) and 92% (TD) of the biopsies with 60% (CP) and 85% (TD) containing more than 150 fibers. Fiber staining was successful in all MG biopsies but failed in 30% (CP) and 16% (TD) of the ST biopsies. Satellite cell staining was successful in 89% (CP) and 85% (TD) for MG and in 70% (CP) and 90% (TD) for ST biopsies, while capillary staining was successful in 88% (CP) and 100% (TD) of the MG and in 86% (CP) and 90% (TD) for the ST biopsies. Intraclass coefficient correlation showed reliable and reproducible measures of all outcomes. This study shows that the percutaneous microbiopsy technique is a safe and feasible tool to collect (repeated) muscle biopsies in young CP and TD children for histological analysis and it provides sufficient muscle tissue of good quality for reliable quantification.

Molecular Genetics Analysis of 70 Chinese Families With Muscular Dystrophy Using Multiplex Ligation-Dependent Probe Amplification and Next-Generation Sequencing

Background: Muscular dystrophy (MD) includes multiple types, of which dystrophinopathies caused by dystrophin (DMD) mutations are the most common types in children. An accurate identification of the causative mutation at the genomic level is critical for genetic counseling of the family, and analysis of genotype-phenotype correlations, as well as a reference for the development of gene therapy. Methods: Totally, 70 Chinese families with suspected MD probands were enrolled in the study. The multiplex ligation-dependent probe amplification (MLPA) was first performed to screen large deletions/duplications of DMD exons in the patients, and then, next-generation sequencing (NGS) was carried out to detect small mutations in the MLPA-negative patients. Results: Totally, 62 mutations of DMD were found in 62 probands with DMD/BMD, and two compound heterozygous mutations in LAMA2 were identified in two probands with MDC1A (a type of congenital MD), indicating that the diagnostic yield was 91.4% by MLPA plus NGS for MD diagnosis in this cohort. Out of the mutations, 51 large mutations encompassing 47 (75.8%) deletions and four duplications (6.5%) were identified by MLPA; 11 small mutations including six (9.7%) nonsense, two (3.2%) small deletions, two splice-site mutations (3.2%), and one small insertion (1.6%) were found by NGS. Large mutations were found most frequently in the hotspot region between exons 45 and 55 (70.6%). Out of the 11 patients harboring point mutations in DMD, 8 were novel mutations. Additionally, one novel mutation in LAMA2 was identified. All the novel mutations were analyzed and predicted as pathogenic according to American College of Medical Genetics and Genomics (ACMG) guideline. Finally, 34 DMD, 4 BMD, 24 BMD/DMD, and 2 MDC1A were diagnosed in the cohort. Conclusion: Our data indicated that the MLPA plus NGS can be a comprehensive and effective tool for precision diagnosis and potential treatment of MD and is particularly necessary for the patients at very young age with only two clinical indicators (persistent hyperCKemia and typical myopathy performance on electromyogram) but no definite clinical manifestations.

Association of Preoperative Diagnosis with Clinical Yield of Muscle Biopsy

Background: Muscle biopsy is a common diagnostic marker for myopathy assessment; however, it has a relatively low pathologic yield of less than 60%. Additionally, both diagnostic and non-diagnostic muscle biopsies can provide guidance for treatment, i.e, provide therapeutic usefulness.

Purpose: We designed a study to determine if having a documented definitive preoperative differential diagnosis would affect the pathologic yield and therapeutic usefulness of muscle biopsies for myopathy. 

Methods: This was a retrospective, single institution chart review of 106 consecutive muscle biopsies in adult patients, which looked at the presence or absence of a definitive preoperative differential diagnosis and relation to diagnostic yield and therapeutic usefulness of muscle biopsies. 

Results: Of 106 muscle biopsies, 50 biopsies (47%) had a definitive preoperative differential diagnosis, 52 biopsies (49%) returned definitive pathology, and 93 biopsies (88%) provided therapeutic information. The presence of a documented differential diagnosis increased the odds of pathologic yield by 3.73 (p-value < 0.01) and therapeutic usefulness by 3.40 (p-value 0.08). If pathology was diagnostic then the therapeutic usefulness of the biopsy was 4.54 times more likely (p-value < 0.01). 

Conclusion: Documentation of a definitive preoperative differential diagnosis, when pursuing muscle biopsy for myopathy, is associated with an increased pathologic diagnostic yield. Definitive pathology was associated with an increase in the therapeutic usefulness of the muscle biopsy.

Does muscle biopsy change the treatment of pediatric muscular disease?

BACKGROUND

Muscle biopsy is performed to confirm the diagnosis of neuromuscular disease and guide therapy. The purpose of our study was to determine if muscle biopsy changed patient diagnosis or treatment, which patients were most likely to benefit from muscle biopsy, and complications resulting from muscle biopsy.

MATERIALS AND METHODS

An IRB-approved retrospective chart review of all patients less than 18 years old undergoing muscle biopsy between January 2010 and August 2016 was performed. Demographics, patient presentation, diagnosis, treatment, hospital course, and follow-up were evaluated. Descriptive and comparative (student's t test, Mann-Whitney U, and Fisher's exact test) statistical analysis was performed. Medians were reported with interquartile range (IQR).

RESULTS

90 patients underwent a muscle biopsy. The median age at biopsy was 5 years (2, 10). 37% (n = 34) had a definitive diagnosis. 39% (n = 35) had a change in their diagnosis. 37% (n = 34) had a change in their treatment course. In the 34 patients who had a change in their treatment, the most common diagnosis was inflammatory disease at 44% (n = 15). In the 56 patients who did not have a change in treatment, the most common diagnosis was hypotonia at 30% (n = 17). There was no difference in patients who had a change in treatment based on pathology versus those that did not. The median length of follow-up was 3 years (1, 5).

CONCLUSIONS

Muscle biopsy should be considered to diagnose patients with symptoms consistent with inflammatory or dystrophic muscular disease. The likelihood of this altering the patient's treatment course is around 40%.

Referring Service Effect on Muscle Biopsy Diagnosis and Management in Myopathy

Introduction

Requests for muscle biopsy for evaluation of myopathy originate from a variety of different specialties. It is unknown whether the specialty of the referring service affects the likelihood of diagnostic biopsy or the therapeutic usefulness of a biopsy.

Methods

We reviewed 106 consecutive muscle biopsies requested by healthcare providers in neurology, rheumatology, family medicine, oncology, and gastroenterology. We tested for an association between referring service and whether the biopsy yielded a definitive pathology result or provided therapeutically useful results.

Results

Half of the biopsies (49%) returned definitive pathology and 88% of the biopsies provided information that contributed to therapeutic decisions. The diagnostic yield for muscle biopsies referred by different services was not statistically significant (p-value 0.1344) nor was the therapeutic yield statistically significant for muscle biopsies referred by different services (p-value 0.5525).

Discussion

The specialty of the service that requests a muscle biopsy does not influence the likelihood of obtaining a definitive pathological diagnosis or therapeutically useful information. Other factors may be more important in determining the likelihood of obtaining a clinically useful biopsy result.

Impact of muscle biopsy on diagnosis and management of children with neuromuscular diseases: A 10-year retrospective critical review

BACKGROUND

Muscle biopsy facilitates morphologic, biochemical, and ultrastructural analysis of muscle for the purpose of making definitive neuromuscular diagnosis. However, muscle biopsy is an expensive, invasive, time-consuming, and resource-dependent procedure. The need for general anesthesia in children also increases the risks associated with this procedure. The aim of this study was to investigate the benefits of muscle biopsies performed over a 10-year period, with a focus on indications, suspected and histopathologic diagnosis, and impact on diagnosis and management decisions.

METHODS

We retrospectively reviewed results of muscle biopsies performed in children at our center during the 2004 to 2014 study period. Clinical presentations, biopsy complications, pathologic results, and changes in management decision were reviewed and analyzed.

RESULTS

Biopsies from 92 patients were included. Mean age of patients was 7.1years, and 66.3% were male. There were no perioperative complications, and definitive diagnosis was made in 74 patients. Regardless of whether pathologic changes were found or not, information gained from muscle biopsy significantly impacted prognosis and subsequent genetic counseling.

CONCLUSIONS

Muscle biopsy is a safe and useful diagnostic tool in children suspected of having neuromuscular diseases, especially in those with muscle diseases. Definitive pathologic diagnosis helps to optimize treatment, counseling, and surveillance.

THE TYPE OF STUDY AND LEVEL OF EVIDENCE

Study of diagnostic test: level 1.

Translational Research in Pediatrics IV: Solid Tissue Collection and Processing

Solid tissues are critical for child-health research. Specimens are commonly obtained at the time of biopsy/surgery or postmortem. Research tissues can also be obtained at the time of organ retrieval for donation or from tissue that would otherwise have been discarded. Navigating the ethics of solid tissue collection from children is challenging, and optimal handling practices are imperative to maximize tissue quality. Fresh biopsy/surgical specimens can be affected by a variety of factors, including age, gender, BMI, relative humidity, freeze/thaw steps, and tissue fixation solutions. Postmortem tissues are also vulnerable to agonal factors, body storage temperature, and postmortem intervals. Nonoptimal tissue handling practices result in nucleotide degradation, decreased protein stability, artificial posttranslational protein modifications, and altered lipid concentrations. Tissue pH and tryptophan levels are 2 methods to judge the quality of solid tissue collected for research purposes; however, the RNA integrity number, together with analyses of housekeeping genes, is the new standard. A comprehensive clinical data set accompanying all tissue samples is imperative. In this review, we examined: the ethical standards relating to solid tissue procurement from children; potential sources of solid tissues; optimal practices for solid tissue processing, handling, and storage; and reliable markers of solid tissue quality.

Muscle histopathology in today's era of molecular genetics: Role and limitations

INTRODUCTION

Past few decades have seen an increasing application of techniques like electron microscopy, western blotting, and molecular genetics in the evaluation of muscle diseases. However, due to their limited availability, histopathological interpretation of muscle biopsies still remains an important component of diagnostic approach to muscle diseases. A systematic methodology is required in the evaluation and interpretation of muscle biopsies. This study was undertaken to analyze the histopathological spectrum of 164 muscle biopsies and to assess the diagnostic yield of basic histopathological procedures in the work up of muscle biopsy.

MATERIALS AND METHODS

Retrospective analysis was done for 164 cases of muscle biopsies. Step-wise approach was adopted to assess the efficacy of routine stains, enzyme histochemistry, and immunohistochemistry. Based on hematoxylin and rosin (H and E) appearance, biopsies were broadly categorized into destructive, nondestructive but myopathic, and inflammatory morphology. Role of special stains, enzyme, and immunohistochemical stains in each category was then evaluated.

RESULTS

On the basis of histopathological features, 164 muscle biopsies were broadly categorized into biopsies with abnormal histopathological features (115) and biopsies with normal histopathology (49). Abnormal muscle biopsies were further categorized into destructive morphology (56.5%), nondestructive but myopathic morphology (30.5%), and inflammatory pathology (13%). A near definitive diagnosis could be made in 115 cases out of 164 muscle biopsies on the basis of routine histopathology, enzyme histochemistry, and immunohistochemistry.

CONCLUSION

Though advanced techniques like electron microscopy, western blotting, and molecular genetics are essential for confirmatory diagnosis, a substantive diagnostic yield can be offered with the basic armamentarium of routine (frozen) stains, enzyme histochemistry, and immunohistochemistry.

[Muscle biopsy in children: Usefulness in 2012]

Muscle biopsy is a mainstay diagnostic tool for investigating neuromuscular disorders in children. We report the yield of pediatric muscle biopsy in a population of 415 children by a retrospective study of 419 biopsies performed between 1/01/2000 and 31/12/2009 in a neuropediatric department, including mitochondrial respiratory chain analysis for 87 children. Two hundred and fifty-five biopsies were from boys (61%) 164 from girls (39%). Their mean age at biopsy was 6.5years; 155 (37%) biopsies were obtained before the child was 5years old. Final histopathological diagnoses were: congenital myopathy (n=193, including 15 structural congenital myopathies); progressive muscular dystrophy (n=75 [18%] including 57 dystrophinopathies); congenital muscular dystrophy (n=17, including six primary merosinopathies); dermatomyositis (n=11); spinal muscular atrophy (n=9, including six atypical spinal muscular atrophies); metabolic myopathy (n=32, including 19 mitochondrial myopathies); encephalomyopathy (n=53 [13%], including 27 with a mitochondrial respiratory chain defect). Pathological diagnosis remained undetermined in 16 cases. In 184 patients (44%), the muscle biopsy revealed specific histopathological anomalies (dystrophic process; specific ultrastructural abnormalities; perifascicular atrophy; neurogenic atrophy; metabolic anomalies) enabling a precise etiological diagnosis. For 85% of progressive muscular dystrophies, the biopsy resulted in a genetic diagnosis after identification of the protein defect. In 15% of the congenital myopathies, histopathological anomalies focused attention on one or several genes. Concerning dystrophinopathies, quantification of dystrophin deficiency on the biopsy specimen contributed to the definition of the clinical phenotype: Duchenne, or Becker. In children with a myopathy, muscle biopsy is often indispensable to establish the etiological diagnosis. Based on the results from this series, muscle biopsy can provide a precise orientation in 45% of patients, leading to a genetic hypothesis.

Evaluation of one hundred pediatric muscle biopsies during a 2-year period in mofid children and toos hospitals

OBJECTIVE

Muscle biopsy is a very important diagnostic test in the investigation of a child with suspected neuromuscular disorder. The goal of this study was to review and evaluate pediatric muscle biopsies during a 2-year period with focus on histopathology diagnosis and correlations with other paraclinic studies.

MATERIALS & METHODS

We investigated 100 muscle biopsies belonging to patients with clinical impression of neuromuscular disorder. These patients have been visited consecutively by pediatric neurologists during 2010 to 2012. Samples were investigated by standard enzyme histochemical and immunohistochemical techniques.

RESULT

Sixty-nine (69%) males and 39 (39%) females with a mean age of 5.7 years were evaluated. Major pathologic diagnoses were Muscular dystrophy (48 cases), Neurogenic atrophy (18 cases), nonspecific myopathic atrophy (12cases), congenital myopathy (6 cases), storage myopathies (4 cases) and in 6 cases there was no specific histochemical pathologic finding. EMG was abnormal in 79 cases. Degree of correlation between EMG and biopsy result was significant in children ≥ 2 years of age.

CONCLUSION

This study confirms the high diagnostic yields of muscle biopsy especially only if standard and new techniques such as enzyme study and immunohistochemistry are implemented. Also, we report 11 cases of Merosin negative congenital muscular dystrophy. This is the largest documented case series of Merosin deficient congenital muscular dystrophy reported from Iran.