This 20-year-old patient presented with acute onset muscle weakness and numbness. Laboratory studies showed elevated CPK (4000) and negative toxin/drug screen. The patient was treated with steroid prior to muscle biopsy.
How would you characterize the abnormal muscle fibers seen in figures #1 – #3?
A. Normal
B. Necrotic
C. Lobulated
D. Acutely angulated
This medium magnification image shows three somewhat pale staining muscle fibers (arrows). The one in the upper right corner contains multiple macrophages.
Esterase enzyme histochemical stain highlights the macrophages within the myofibers.
The myofibers show are variably highlighted by alkaline phosphatase enzyme histochemical stain.
Correct Answer: Necrotic
These represent necrotic muscle fibers. In this case all of the damaged myofibers had a similar appearance suggesting acute monophasic injury.
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