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NeuroTest Question #81 Next question Previous question

Answer: Periodic acid Schiff (PAS) reaction. Level of difficulty: 2 NeuroTest NeuroLearn NeuroHelp

Discussion:

The stain being used here is periodic acid Schiff (PAS). This specimen was obtained from a case with McArdle's disease (glycogenosis type V). There is increased PAS positive (Þ) material that can be digested by diastase (diastase sensitive). These histochemical features are consistent with glycogen. [Click here to see a case of McArdle's disease]
Oil red O is used to detect abnormal lipid storage. [Click here to see a photo of Oil red O stain in abnormal neutral fat (lipid) storage]
Modified Gomori's trichrome is a stain that can be used to detects several changes including ragged red fibers in mitochondrial myopathies, rimmed vacuoles in inclusion body myositis and target fibers in neurogenic atrophy. [Click here to see a ragged red fiber]
Succinate dehydrogenase is present in the mitochondria. Accumulation of abnormal mitochondria in mitochondrial myopathies would lead to depositions that can be detected by succinate dehydrogenase preparations. [Click here to see a fiber with accumulation of mitochondria in a case of mitochondrial myopathy]
In esterase preparation, positive reaction can be seen in the neuromuscular junction (acetylcholinesterase), nucleus, and inflammatory cells. Atorphic fibers in neurogenic atrophy often appear angulated and show increased reactivity for esterase. [Click here to see a photo of fibers in neurogenic atrophy]