A. Inflammatory myopathy
B. Mitochondrial myopathy
C. Motor neuron disease
D. Muscle disuse
E. Myotonic dystrophy
4. On Gomori trichrome staining, frozen sections of a muscle biopsy reveal numerous myofibers with a ragged profile and red subsarcolemmal deposits, as shown in this picture. This finding suggests which of the following muscle conditions?
B. Immune-mediated myopathies
C. Lipid storage diseases
D. Mitochondrial myopathies
E. Muscular dystrophies
5. A 4-year-old male presents with a history of progressive awkwardness and frequent falls. A clinical diagnosis of Duchenne muscular dystrophy can be confirmed or ruled out by:
A. Biochemical studies of mitochondrial metabolism
B. Genetic analysis for detection of trinucleotide repeats
C. Immunohistochemistry for dystrophin on muscle biopsy
D. Immunohistochemistry for dysferlin
E. Measurement of blood creatine kinase
F. Ultrastructural study of neuromuscular junctions
6. A 60-year-old woman presents with progressive weakness and pain in the proximal muscles of both upper and lower extremities. Blood creatine kinase (CK) is very elevated. A biopsy of the quadriceps muscle reveals the changes depicted in this photomicrograph. Which of the following is the most likely diagnosis?
A. Denervation atrophy
C. Inclusion body myositis
D. Myasthenia gravis
7. A 58-year-old man presents to medical attention with progressive distal weakness, particularly in the extensor muscles of the arms. His blood levels of creatine kinase are markedly increased. A muscle biopsy reveals the changes shown in this photomicrograph. Furthermore, many atrophic angular myofibers are seen. Which of the following is the most likely diagnosis?