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Case Study 83 Leonidas Arvanitis, MD. Question 1:. The patient is a 50-year-old female with AIDS complaining of a 3 month history of muscle weakness Laboratory studies showed a normal EMG and CK levels Describe the findings on an open biopsy of the left quadriceps muscle:
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Question 1: • The patient is a 50-year-old female with AIDS complaining of a 3 month history of muscle weakness • Laboratory studies showed a normal EMG and CK levels • Describe the findings on an open biopsy of the left quadriceps muscle: • Click hereto view frozen section H&E slide
Answer 1: • Abnormal variation in myofiber sizes (10-100 microns) • Clustered and scattered angulated atrophic fibers • No excess of internalized nuclei • Occasional nuclear clumps • No degenerating or regenerating fibers • No inflammatory infiltrates
Question 2: • What is the most significant histologic finding seen in this biopsy specimen?
Answer 2: • Abnormal variation in myofiber sizes (10-100 microns) • Clustered and scattered angulated atrophic fibers • No excess of internalized nuclei • Occasional nuclear clumps • No degenerating or regenerating fibers • No inflammatory infiltrates
Question 3: • How does the pattern of fiber atrophy help us determine the cause for the atrophy?
Answer 3: • Changes random and diffuse • Myopathy/dystrophy • Presence of small angulated fibers • Suggests denervation • Presence of small group atrophy • Denervation • Presence of large group atrophy • Denervation • Presence of perifascicular atrophy • Dermatomyositis
Question 4: • In our case the atrophy is random and diffuse suggestive of a myopathy or dystrophy • What histochemical stain would be most helpful in further defining the specific muscle types involved?
Answer 4: • ATPase 9.4 • ATPase 4.6 • Click here to view an ATPase 9.4 stain of a normal muscle biopsy • Click here to view an ATPase 4.6 stain of a normal muscle biopsy
Question 5: • What is the normal staining pattern of muscle fibers on ATPase 9.4 and 4.6 respectively?
Answer 5: -, +, ++, +++ represent increasing intensity of stain
Question 6: • What is the staining pattern of ATPase stains in our case? • Click here to view ATPase 9.4 stain • Click here to view ATPase 4.6 stain
Answer 6: • The atrophic muscle fibers are almost exclusively of the type 2 subtype
Question 7: • What additional clinical information would be useful to better define the disease process?
Answer 7: • History of alcohol abuse • Medication history • Other associated comorbidities • In our case the patient was treated with corticosteroids
Question 8: • What are the causes of type 2 myofiber atrophy?
Answer 8: • Alcohol use • Steroids • Disuse • Endocrinopathies • Connective tissue disorders
Question 9: • Which subtype of type 2 myofibers are particularly affected?
Answer 9: • Type 2B fibers
Question 10: • What is your final diagnosis?
Answer 10: • Type 2 myofiber atrophy due to corticosteroid use