What is EM?

Electron microscopy (EM) is a technique for obtaining high-resolution images of specimens (ultrastructure).  

Procedures

What is the role of EM in Pediatric Pathology?

• EM has been widely used in pediatric pathology when dealing with:
  • Medical kidney disease
  • Liver disease
  • Metabolic disorder/storage disease
  • Mitochondrial disorder
  • Neuromuscular disease
  • Interstitial lung disease, pulmonary alveolar proteinosis, and primary ciliary dyskinesia.
• Recent ancillary testing (e.g., immunohistochemical staining and molecular genetic testing) has replaced many diagnostic roles of ultrastructural pathology.

Challenges in Maintaining EM in Lab

1. The operation costs are too expensive.
   • EM laboratories require costly equipment, such as a transmission electron microscope, digital camera/image processing system, ultramicrotome, automated tissue processor, and maintenance service subscription accessible all the time.
2. The number of EM specimens is too small to cover the operation cost.
   • Hospitals receiving fewer EM cases tended to use outside reference EM laboratories.
3. Better ancillary testing has replaced the role of EM.
   • Especially true in tumor diagnostics, where immunohistochemical staining and molecular testing have become essential tools.
   • Likewise, molecular genetic testing has gradually replaced muscle and cilia biopsies.
4. Many pathology residency and fellowship programs do not include education on the diagnostic role of EM.
   • In addition, few books and articles on pediatric EM diagnostics have been published recently.
5. The number of pathologists expertizing in EM, especially in non-renal EM, has been decreasing.
   • The shortage is caused by the retirement of EM specialists and the difficulty in finding young pathologists interested in EM.
   • This problem is closely related to the above issue 4.
6. A significant shortage of EM technicians, many of whom are also getting old.
   • While it takes a long time (e.g., 1-2 years) to train independent EM technicians, it is also challenging to identify histotechnologists interested in learning EM skills.

References

• Stocker JT, Dehner LP, Husain AN. Stocker and Dehner’s Pediatric Pathology. 3rd ed. Philadelphia, PA, USA: Lippincott Williams & Wilkins; 2011.
• Williams MJ. Electron microscopy in the Veterans Administration for service pathology: some administrative aspects of the program. Hum Pathol. 1975;6:399-400.
• Mackay B, Ordo ́ ñez N.G. The role of the pathologist in the evaluation of poorly differentiated tumors. Semin Oncol. 1982;9:396-415.
• Williams MJ, Uzman BG. Uses and contributions of diagnostic electron microscopy in surgical pathology: a study of 20 Veterans Administration hospitals. Hum Pathol. 1984;15:738-745.
• Tucker JA. The continuing value of electron microscopy in surgical pathology. Ultrastruct Pathol. 2000 Nov-Dec;24(6):383-9.
• Shoemark A, Boon M, Brochhausen C, Bukowy-Bieryllo Z, De Santi MM, Goggin P, Griffin P, Hegele RG, Hirst RA, Leigh MW, Lupton A, MacKenney K, Omran H, Pache JC, Pinto A, Reinholt FP, Schroeder J, Yiallouros P, Escudier E; representing the BEAT-PCD Network Guideline Development Group. International consensus guideline for reporting transmission electron microscopy results in the diagnosis of primary ciliary dyskinesia (BEAT PCD TEM Criteria). Eur Respir J. 2020 Apr 16;55(4)
• Warren M, Shimura M, Wartchow EP, Yano S. Use of electron microscopy when screening liver biopsies from neonates and infants: experience from a single tertiary children’s hospital (1991-2017). Ultrastruct Pathol. 2020 Jan 2;44(1):32-41.
• Warren M, Mierau G, Wartchow EP, Shimada H, Yano S. Histologic and ultrastructural features in early and advanced phases of Zellweger spectrum disorder (infantile Refsum disease). Ultrastruct Pathol. 2018 May-Jun;42(3):220-227.
• Taweevisit M, Thorner PS. Electron Microscopy Can Still Have a Role in the Diagnosis of Selected Inborn Errors of Metabolism. Pediatr Dev Pathol. 2019 Jan-Feb;22(1):22-29.