Establishment of normal myofiber size distribution in children and young adults

Michael W. Lawlor, Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, United States.
Marta Margeta, Department of Pathology, University of California San Francisco, San Francisco, CA, United States.
Karra A. Jones, Department of Pathology, Duke University School of Medicine, Durham, NC, United States.
Benedikt Schoser, Department of Neurology, Friedrich-Baur-Institute, Ludwig-Maximilians-University Munich, Munich, Germany.
Jennifer A. Cotter, Children's Hospital Los Angeles, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States.
Veena Rajaram, Department of Pathology, UT Southwestern Medical Center. Dallas, TX, United States.
Steven A. Moore, Carver College of Medicine, The University of Iowa, Iowa City, IA, United States.
Mariah J. Prom, Diverge Translational Science Laboratory, Milwaukee, WI, United States.
Margaret Beatka, Diverge Translational Science Laboratory, Milwaukee, WI, United States.
Emily Ott, Diverge Translational Science Laboratory, Milwaukee, WI, United States.
Rebecca A. Slick, Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, United States.
Michael P. Collins, Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, United States.
Ann Esselman, Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, United States.
Nazima Shahnoor, Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, United States.
Susan Danielson, Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, United States.
Hui Meng, Diverge Translational Science Laboratory, Milwaukee, WI, United States.
Fatbardha Varfaj, Formerly of Astellas Gene Therapies (formerly Audentes Therapeutics), San Francisco, CA, United States.
Suyash Prasad, Formerly of Astellas Gene Therapies (formerly Audentes Therapeutics), San Francisco, CA, United States.
Salvador Rico, Formerly of Astellas Gene Therapies (formerly Audentes Therapeutics), San Francisco, CA, United States.
Jun Lee, Formerly of Astellas Gene Therapies (formerly Audentes Therapeutics), San Francisco, CA, United States.
Suresh N. Kumar, Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, United States.
Heather Gordish Dressman, Children's National Hospital and the George Washington University, Washington, DC, United States.

Document Type

Journal Article

Publication Date

11-4-2025

Journal

Journal of neuropathology and experimental neurology

DOI

10.1093/jnen/nlaf123

Keywords

fiber size; growth curve; minFeret diameter; muscle biopsy; muscle growth; muscle pathology

Abstract

Abnormalities of myofiber size are often of diagnostic significance on skeletal muscle biopsies, mainly when myofibers are excessively small. The establishment of standards for myofiber size in children has been hampered until recently by the lack of tools to assess large numbers of fibers across a sizeable number of samples. This study describes the assessment of myofiber size in 349 histologically normal patient biopsy specimens obtained between 4 weeks and 25 years of life and corresponding primarily to locations in the thigh/quadriceps/vastus lateralis region. Biopsy specimens were selected for inclusion based on histologically normal light microscopic findings and minimal technical artifacts. H&E-stained slides were scanned and evaluated for minFeret diameter using a Visiopharm software app (APP #10164). MinFeret diameter fiber size data were then grouped into 18 age cohorts to establish normal ranges for males and females within each age cohort. A pilot study to compare known abnormal cases to these normal ranges was then performed to demonstrate how cases with abnormal fiber size might compare to these standards. This dataset provides a user-friendly and applicable set of standard fiber size ranges to assist in diagnostic and scientific work in children and young adults.

Department

Pediatrics

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