Vascular pathology in dermatomyositis and anatomic relations to myopathology

Authors

  • Alan Pestronk MD,

    Corresponding author
    1. Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8111, St. Louis, Missouri 63110, USA
    2. Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
    • Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8111, St. Louis, Missouri 63110, USA
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  • Robert E. Schmidt MD, PhD,

    1. Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
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  • Rati Choksi MS

    1. Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8111, St. Louis, Missouri 63110, USA
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Abstract

The causes of perifascicular myofiber atrophy and capillary pathology in dermatomyositis are incompletely understood. We studied 11 dermatomyositis muscles by histochemistry, immunohistochemistry, and ultrastructure. We found that endomysial capillaries within regions of perifascicular atrophy are not entirely lost, but they have reduced size, endothelial loss, C5b9 complement deposits, and relatively preserved connective tissue molecules and pericytes. In all muscles, the perimysium varies regionally. Some areas contain intermediate-sized vessels. Others are avascular. In dermatomyositis, vascular perimysium contains abnormal vessel fragments, perivascular inflammation, and increased PECAM-1. Perifascicular myofiber atrophy and capillary pathology are concentrated near the avascular perimysium. We conclude that both perimysial intermediate-sized vessels and endomysial capillaries within regions of perifascicular myofiber atrophy are abnormal in dermatomyositis. Capillary damage and myofiber atrophy are concentrated in regions distant from intermediate-sized perimysial vessels. Chronic immune vascular damage and insufficiency in dermatomyositis may cause ischemia, myofiber atrophy, and capillary damage in “watershed” regions of muscle near the avascular perimysium. Muscle Nerve, 2010

Ancillary