Myofibrillar myopathy with abnormal foci of desmin positivity. I. Light and electron microscopy analysis of 10 cases

Satoshi Nakano, Andrew G. Engel, Andrew J. Waclawik, Alison M. Emslie-Smith, Neil A. Busis

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152 Scopus citations

Abstract

A number of myopathies whose common denominator is abnormal foci of desmin positivity have been described under the rubrics of spheroid body myopathy, cytoplasmic body myopathy. Mallory body myopathy, myopathy with granulofilamentous inclusions, desmin storage myopathy, and intermediate filament myopathy. In this study we reevaluate the light microscopic and ultrastructural features of the myopathy with abnormal loci of desmin positivity. In 10 cases of the disease, ultrastructural analysis reveals 2 major types of lesions: (a) loci of myofibrillar destruction and (b) hyaline structures that appear as spheroidal bodies on electron microscopy. The loci of myofibrillar destruction consist of fiber areas containing disrupted myofilaments, Z-disk-derived bodies, dappled dense structures of Z-disk origin, and streaming Z-disks that are sometimes adjacent to lakes of dense material. The spheroid bodies are composed of compacted and degraded myofibrillar elements. Membrane-bound vacuoles harboring degenerating membranous organelles are a less frequent and probably secondary abnormality. None of the lesions in muscle comprise 8 to 10 nm intermediate filaments. The findings imply that spheroid body myopathy, cytoplasmic body myopathy. Mallory body myopathy, and myopathy with granulofilamentous inclusions are consequences of a single or closely related pathologic processes. Because the common denominator appears to be focal dissolution of the myofibrils followed by accumulation of the products of the degradative process, we propose the term myofibrillar myopathy to cover the observed spectrum of pathologic changes.

Original languageEnglish (US)
Pages (from-to)549-562
Number of pages14
JournalJournal of Neuropathology and Experimental Neurology
Volume55
Issue number5
DOIs
StatePublished - May 1996

Keywords

  • Desmin
  • Electron microscopy
  • Myofibrils
  • Myopathy
  • Spheroid bodies
  • Z disk

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Neurology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience

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