muscle pathology (Q1-25)

[wcb22]

Question 1 For several months a 37 year old female has noted increasing fatigue toward the end of the day. She does not have myalgia or arthralgia. She makes more mistakes typing, and she can hardly keep her eyes open. She seems better in the morning. A month later she has difficulty swallowing and speaking. Which of the following findings is most likely to be present:
A Antibody to smooth muscle
B Symmetric lower limb muscle atrophy
C Muscular fasciculations
D Acetylcholine receptor degradation
E Inflammation of skeletal muscle
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Question 2 An 8-year-old male gets tired easily and can be outrun by his 5-year-old brother, even though his legs appear well-developed. His serum creatine kinase is 550 U/L. A gastrocnemious biopsy shows marked interstitial fibrosis with atrophy of many fibers and increase in size of others, but no inflammation. Immunohistochemical staining with antibody to dystrophin shows a lack of staining around the fibers. Over the next 5 years, he becomes progressively weaker until he is confined to a wheelchair. He is probably:
A The victim of an X-linked recessive disorder
B Not trying hard enough
C The victim of myotonic dystrophy
D The victim of an autoimmune disease
E Homozygous for an autosomal recessive disorder
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Question 3 A 29 year old female has increasing muscular pain, particularly involving her upper arms and legs. She has difficulty swallowing. Her fingers often become blue and painful when exposed to cold. She has noted a pale bluish-purple discoloration of her upper eyelids. Which of the following light microscopic features is most likely to be present in a muscle biopsy:
A Myositis with lymphocytic infiltrates
B Grouped atrophy
C Extensive fibrosis
D Absence of immunohistochemical staining for dystrophin
E "Ragged red fibers" with trichrome staining
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Question 4 A 47 year old male has experienced progressive, symmetrical muscular weakness for several years. He has no myalgias or arthralgias. His mental status is unchanged. There is no history of traumatic injury. Within the past two months he has had increasing difficulty with swallowing and speaking. On physical examination, fasciculations of the tongue are noted. A muscle biopsy is obtained, and the most likely microscopic finding is:
A Grouped atrophy
B Inflammation
C Fibrosis
D Irregular variation in fiber size
E Fatty infiltration
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Question 5 A 45 year old woman has noted increasing weakness and has more difficulty climbing stairs or getting out of her car. She reports no myalgias. She has no difficulty typing. A physical examination reveals 4/5 motor strength in proximal muscule groups and 5/5 strength in distal muscle groups of extremities. An abdominal CT scan reveals a 2 cm mass in the right adrenal gland. A deltoid biopsy shows fiber atrophy, predominantly affecting type 2 fibers. Which of the following conditions is she most likely to have:
A Grave's disease
B Lambert-Eaton syndrome
C Leigh syndrome
D Myotonic dystrophy
E Cushing's syndrome
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Question 6 A 19 year old previously healthy university student finds it increasingly more difficult to climb the stairs to her dormitory room. She has difficulty getting out of a chair. She notes the presence of a violaceous skin rash that involves her eyelids. She reports worsening myalgias. On physical examination, she has periorbital edema in addition to the rash. She has symmetric muscle weakness with only 1/5 strength in both upper and lower extremities. She has an HLA-DR3 phenotype. A gastrocnemious biopsy is performed. Which of the following microscopic findings in the biopsy is most likely to be present:
A Grouped atrophy
B Eosinophilic infiltrates
C Perivascular lymphocytes
D Type II fiber atrophy
E Increased glycogen deposits
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Question 7 A 68 year old male dies from an esophageal carcinoma. She had a 30 kg weight loss over the 14 month course of her disease from the time of initial diagnosis. At autopsy, microscopic examination of skeletal muscle would most likely show:
A Degeneration and regeneration
B Necrosis
C Inflammation
D Metastasis
E Atrophy
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Question 8 Severe myalgia with fever are present in a 28-year-old male several weeks after he returned from a camping trip to Alaska. On that trip, he and his fellow travellers hiked extensively. They ate wild game they cooked themselves. A CBC shows a total WBC count of 14,600/microliter, Hgb 14.8 g/dL, Hct 45.0%, MCV 93 fL, and platelet count 215,000/microliter. WBC differential count shows 66 segs, 5 bands, 10 lymphs, 7 monos, and 12 eos. A muscle biopsy would most likely show:
A Grouped atrophy
B Encysted larvae
C Degeneration
D Neutrophilic infiltrates
E Fibrosis
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Question 9 A 19 year old male is involved a a motorcycle accident in which is incurs a severe back injury with fracture-dislocation of C8. At the scene, it is noted that he has no sensation in his lower chest down to his toes, and he cannot move his legs. A muscle biopsy taken from the gastrocnemius muscle a month later will be most likely to show:
A Inflammation
B Small angular and atrophic muscle fibers
C Grouped atrophy of muscle fibers
D Fibrosis
E Degeneration and regeneration of muscle fibers
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Question 10 A 30-year-old man has exhibited slowly progressive muscle weakness over several years. He has no myalgias. He now has difficulty ambulating and picking up heavy objects, even though he used to be a weightlifter. He has a serum creatine kinase of 450 U/L. A deltoid biopsy shows variation in fiber size and immunohistochemical staining shows only focal positivity for dystrophin around the fibers. He probably has:
A Dermatomyositis
B Becker muscular dystrophy
C Werdnig-Hoffman disease
D Amyotrophic lateral sclerosis
E Poliovirus infection
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Question 11 A 50 year old man has progressive symmetrical muscle weakness. He has no myalgia or arthralgia. Five years after the onset of this disease, he is confined to bed. A year later he has difficulty speaking and swallowing. A muscle biopsy demonstrates grouped atrophy of muscle fibers with no inflammation or necrosis. These findings are most typical for a disease that is characterized as a(an):
A Genetic lack of myophosphorylase
B Denervation atrophy
C Muscular dystrophy
D Autoimmune myopathy
E Corticosteroid-induced myopathy
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Question 12 An infant displays mild generalized muscular weakness. As the child matures, the weakness remains mild and relatively nonprogressive. A serum creatine kinase is 55 U/L. The antinuclear antibody test is negative. Deep tendon reflexes are normal. There is no significant muscle wasting. The child does not have myalgias or arthralgias. The child has normal mental function. Which of the following etiologies for this condtion is most likely to be present:
A Diminished dystrophin on muscle fibers
B Antibody against skeletal muscle proteins
C Congenital cytomegalovirus infection
D Congenital myopathy
E Deficiency of acid maltase
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Question 13 A 13 year old boy fatigues easily and complains of cramping pain with exercise 'all over' after only a few laps around the track in his high school physical education class. One day, the coach makes him continue much longer, and he develops myoglobinuria. If he rests briefly, he can continue for a few more laps. He has normal range of motion and agility. At rest, or with activities of daily living, he experiences no myalgias. Physical examination reveals no evidence for muscle wasting. Muscle strength is 5/5 in all extremities. Deep tendon reflexes are 2+. Which of the following mechanisms is most likely to account for these findings:
A Lack of dystrophin on skeletal muscle fibers
B Absence of anterior horn cells
C Trichinella spiralis infection
D Corticosteroid therapy for asthma
E Decreased myophosphorylase
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Question 14 Hours after consuming a meal that included home-canned peas, a man and his wife began to develop weakness and progressive respiratory failure. This is probably the result of:
A Salmonellosis
B Botulism
C Diphtheria
D Gas gangrene
E Tetanus
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Question 15 A 9 year old girl gets tired easily but is still able to perform nomal daily activities. Through young adulthood, she continues to exhibit mild generalized muscle weakness. On physical examination, she has motor strength 2/5 in all extremities along with hypotonia. Reflexes are normal. She has no myalgias. A deltoid biopsy shows muscle fibers with numerous rod-shaped intracytoplasmic inclusions. She is most likely to have:
A An autoimmune disease
B Lower motor neuron disease
C Muscular dystrophy
D A congenital myopathy
E Myophosphorylase deficiency
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Question 16 A 35-year-old female had a diagnosis of polymyositis made with a muscle biopsy. Following a course of corticosteroid therapy, she continues to have muscular weakness, particular in proximal muscles. The serum creatine kinase (CK) is only 41 U/L, and an electromyogram demonstrates no myopathic changes. These findings most strongly suggest:
A Treatment failure
B Upper motor neuron disease
C Corticosteroid-induced myopathy
D McArdle's disease
E Duchenne muscular dystrophy
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Question 17 Which one of the following histologic findings on muscle biopsy would be most indicative of an active polymyositis:
A Marked fiber hypertrophy
B Many fibers undergoing degeneration and regeneration
C Grouping of atrophic fibers
D Extensive endomysial and perimysial fibrosis
E Subsarcolemmal glycogen deposition
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Question 18 A 7 year old child becomes more irritable and complains of a headache and neck pain. Several weeks later, her parents note that she appears listless and has difficulty getting up and moving about. Physical examination reveals decreased motor strength in her lower extremities along with hyporeflexia, but sensation is intact. She remains mentally alert. She exhibits no seizure activity. A gastrocnemius biopsy shows grouped atrophy. Her serum creatine kinase is 20 U/L. A CBC shows a WBC count of 5500/microliter with 65 segs, 3 bands, 19 lymphs, 9 monos, 2 eosinophils, and 2 basophils, Hgb 13.3 g/dL, Hct 40%, MCV 93 fL, and platelet count 297,000/microliter. Which of the following infectious agents has most likely produced these findings:
A Cytomegalovirus
B Rabies virus
C Herpes simplex virus
D Echovirus
E Poliovirus
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Question 19 For several years, a 55 year old male has fatigued easily as the day progresses, but after a night's rest feels better in the morning. At first, he noted that his eyelids drooped, but now he has difficulty chewing food, particularly meat. Physical examination reveals reduced strength in both right and left extremities. Deep tendon reflexes are normal. A biopsy of muscle reveals no major histologic abnormalities. He is most likely to have:
A Myasthenia gravis
B Duchenne muscular dystrophy
C Trichinosis
D Werdnig-Hoffman disease
E Amyotrophic lateral sclerosis
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Questions 20 and 21: Click on the checkbox first, then the lettered item: (20) Progressive, symmetrical muscular weakness is experienced by a 50-year-old male over several years' time. At first, he had difficulty climbing stairs. Two years later he was confined to a wheelchair. Another two years passed and he could no longer feed himself.
(21) A 25-year-old female has episodes of myalgia involving nearly every major muscle group of her extremities. She has no joint deformities.
A Atrophy of muscle fibers with fibrosis
B Grouped atrophy of muscle fibers
C Cachexia with metastatic carcinoma
D Positive antinuclear antibody test
E Botulinum perfringens toxin
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Questions 22 and 23: Click on the checkbox first, then the lettered item: (22) Neutrophils with destruction of individual muscle fibers are observed on muscle biopsy in a 22-year-old female with a lilac-colored eyelid rash.
(23) Acetylcholine receptor antibody is found in a 34-year-old female who is easily fatigued by repetitive tasks such as typing.
A Myasthenia gravis
B Polymyositis
C Werdnig-Hoffman disease
D McArdle's disease
E Amyotrophic lateral sclerosis
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Question 24 A 3 year old girl has increasing weakness involving all of her extremities so that she has difficulty moving about. Her parents indicate that she has had no major illnesses. She was a term birth without complications. She has no fever. Laboratory findings, including a CBC, chemistry panel, and urinalysis, are unremarkable. Muscle biopsy reveals grouped atrophy of muscle fibers. The most likely diagnosis is:
A Myasthenia gravis
B Werdnig-Hoffman disease
C Duchenne muscular dystrophy
D Polymyositis
E Pompe's disease
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Question 25 A young male comes to the emergency room because of the onset over a couple of weeks of worsening fever, weakness, malaise, and tender aching muscular pain "all over". Laboratory findings include an elevated serum creatine kinase and an elevated white blood cell count with prominent eosinophilia with differential count. The best diagnosis is:
A Trichinella spiralis infection
B Werdnig-Hoffman disease
C Becker muscular dystrophy
D Mitochondrial myopathy
E Polymyositis-dermatomyositis
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