Muscle, Denervation atrophy secondary to polyneuropathy, myosin S stain [LMP83152]
Keywords
muscle, denervation atrophy, polyneuropathy, inflammatory polyneuropathy
Clinical History
Acute neurological deterioration with absent motor and sensory responses in the face, arms, and legs on nerve conduction studies and electromyogram. Suspicion of Guillain-Barré syndrome/acute motor and sensory axonal neuropathy. Left lower leg muscle biopsy.
Clinical Discussion
Inflammatory polyneuropathies such as Guillain-Barré syndrome can lead to loss of innervation and muscle injury.
Muscle injury can be broadly classified based on two mechanisms: 1) myopathic injury (direct damage to myofibers), and 2) neurogenic injury (from disruption of muscle innervation). Neurogenic injury is characterized by increased variability in the size and shape of myocytes - with atrophy occurring in clusters (grouped atrophy) - and myofibers which take on an angulated shape.
Grouping of fiber types with loss of the normal checkerboard distribution on immunohistochemistry for myosin S and myosin F is a diagnostic feature of neurogenic injury. This case also shows a predominance of type I fibers and selective atrophy of type II fibers which can be seen in prolonged corticosteroid use, muscle disuse, and denervation.
This slide shows myosin S stain. See Related Content for H&E and myosin F stains.
Muscle injury can be broadly classified based on two mechanisms: 1) myopathic injury (direct damage to myofibers), and 2) neurogenic injury (from disruption of muscle innervation). Neurogenic injury is characterized by increased variability in the size and shape of myocytes - with atrophy occurring in clusters (grouped atrophy) - and myofibers which take on an angulated shape.
Grouping of fiber types with loss of the normal checkerboard distribution on immunohistochemistry for myosin S and myosin F is a diagnostic feature of neurogenic injury. This case also shows a predominance of type I fibers and selective atrophy of type II fibers which can be seen in prolonged corticosteroid use, muscle disuse, and denervation.
This slide shows myosin S stain. See Related Content for H&E and myosin F stains.
Related Content
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