The Role of Electron Microscopy in the Assessment of Dermatomyositis: A Retrospective Pilot Study on Skeletal Muscle Biopsies

Aims: To assess the contribution of electron microscopy in the process of muscle biopsies evaluation for dermatomyositis.
Study Design: Retrospective review of muscle biopsy cases.
Place and Duration of Study: Pathology Department of King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia from January 2008 to January 2012.
Methodology: Samples from cases suspected to have dermatomyositis were reviewed for light and ultrastructural morphological examination. Tubuloreticular inclusions (TRI) were considered present if these undulating tubules were detected in the endothelial cells of the capillaries.
Results: Out of ten cases that were suspected for dermatomyositis, three cases showed classical light microscopic features of dermatomyositis, two of which showed TRI. Among four cases with non-specific light microscopic features that can be seen in dermatomyositis, TRI were detected in two of these four cases. Among three cases with non-contributory light microscopy, TRI were found in all of these three cases.
Conclusion: Electron microscopy -if feasible- may be useful in the screening of muscle biopsies, when clinically or morphologically suspected inflammatory myopathies are considered. Further studies to assess the significance of TRI with a larger number of cases, clinical data correlation and immunostains are needed.