USMLE USMLE Certifications USMLE-STEP-3 Questions & Answers

• Question 611:

  A 72-year-old man with a diagnosis of prostate cancer was recently seen in the clinic for restaging and reevaluation. His bone scan showed development of widespread osseous metastases and his PSA was rising. He was started on leuprolide acetate, a gonadotropin releasing-hormone (GnRH) agonist. He now returns to the clinic complaining of new severe mid-thoracic back pain, which is worse with recumbency and worse with Valsalva maneuver. He also reports that he has a brief but intense electric shock sensation in his lower extremities when he bends over to tie his shoes. On physical exam, he had localized tenderness over the mid-thoracic spine, but his motor strength, sensation, and deep tendon reflexes are all intact.

  What is the most likely explanation for the rapid onset of back pain and neurological difficulty after the initiation of leuprolide?

  A. The patient's tumor was likely androgen-independent and so did not respond to hormonal therapy, with rapid progression of his cancer.

  B. The patient likely experienced vasomotor symptoms such as hot flashes and discontinued the therapy, leading to the tumor progression.

  C. The GnRH agonist produced a transient rise in serum testosterone, causing a "tumor flare."

  D. The patient's response was an unpredictable idiopathic drug reaction.

  E. There is no plausible mechanism by which the medication could cause the development of spinal cord compression, and so it is likely unrelated to the patient's symptoms

  Correct Answer: C Section: (none)

  Explanation:

  The patient has symptoms of spinal cord compression and needs an urgent MRI to establish the diagnosis. Spinal cord compression usually develops when patients have metastases to the vertebral body with epidural extension of the tumor, displacing the underlying thecal sac, and causing cord edema and injury. Patients with cord compression usually experience new or worsening pain symptoms days or weeks before the development of motor weakness below the level of compression. Loss of sensation and loss of bowel or bladder control occur even later. Clues that the pain symptoms may represent cord injury include pain that is worse with recumbency or Valsalva and the occurrence of Lhermitte's sign, an electric sensation down the back and into the extremities with extension or flexion of the neck or spine.

  Initiation of therapy, such as radiation therapy or neurosurgical intervention, might be necessary later but would be premature before the diagnosis is established with an imaging study. If the patient's history or physical exam suggests spinal cord compression, initiation of corticosteroids should be started immediately while diagnostic imaging is pending. Pain control with adequate narcotic analgesia is important and may be instituted while the appropriate diagnostic studies are being obtained. Delay of 1 week would be inappropriate due to the urgent nature of the problem and risk of neurological compromise. The patient's neurological status at the time of diagnosis is the most important prognostic factor: 7580% of patients who are ambulatory at the time of diagnosis will retain locomotion. But, if already paraplegic, only 10% will regain the ability to walk. While this patient appeared neurologically intact, the development of neurological deficits can progress over a period of days, making rapid diagnosis and institution of appropriate therapy such as corticosteroids and radiotherapy an urgent consideration. Other factors such as age, presence of co-morbid medical conditions, functional status, and tumor androgensensitivity are important to the patient's overall cancer prognosis

• Question 612:

  A 72-year-old man with a diagnosis of prostate cancer was recently seen in the clinic for restaging and reevaluation. His bone scan showed development of widespread osseous metastases and his PSA was rising. He was started on leuprolide acetate, a gonadotropin releasing-hormone (GnRH) agonist. He now returns to the clinic complaining of new severe mid-thoracic back pain, which is worse with recumbency and worse with Valsalva maneuver. He also reports that he has a brief but intense electric shock sensation in his lower extremities when he bends over to tie his shoes. On physical exam, he had localized tenderness over the mid-thoracic spine, but his motor strength, sensation, and deep tendon reflexes are all intact.

  What is the most important prognostic factor regarding this patient's ultimate neurological outcome?

  A. patient's age and co-morbid conditions at time of diagnosis

  B. degree of neurological impairment at time of diagnosis and initiation of therapy

  C. number of vertebral bodies affected by metastatic disease

  D. tumor sensitivity to androgen stimulation or inhibition

  E. patient's overall functional status before the development of the spinal cord injury

  Correct Answer: B Section: (none)

  Explanation:

  The patient has symptoms of spinal cord compression and needs an urgent MRI to establish the diagnosis. Spinal cord compression usually develops when patients have metastases to the vertebral body with epidural extension of the tumor, displacing the underlying thecal sac, and causing cord edema and injury. Patients with cord compression usually experience new or worsening pain symptoms days or weeks before the development of motor weakness below the level of compression. Loss of sensation and loss of bowel or bladder control occur even later. Clues that the pain symptoms may represent cord injury include pain that is worse with recumbency or Valsalva and the occurrence of Lhermitte's sign, an electric sensation down the back and into the extremities with extension or flexion of the neck or spine.

  Initiation of therapy, such as radiation therapy or neurosurgical intervention, might be necessary later but would be premature before the diagnosis is established with an imaging study. If the patient's history or physical exam suggests spinal cord compression, initiation of corticosteroids should be started immediately while diagnostic imaging is pending. Pain control with adequate narcotic analgesia is important and may be instituted while the appropriate diagnostic studies are being obtained. Delay of 1 week would be inappropriate due to the urgent nature of the problem and risk of neurological compromise. The patient's neurological status at the time of diagnosis is the most important prognostic factor: 7580% of patients who are ambulatory at the time of diagnosis will retain locomotion. But, if already paraplegic, only 10% will regain the ability to walk. While this patient appeared neurologically intact, the development of neurological deficits can progress over a period of days, making rapid diagnosis and institution of appropriate therapy such as corticosteroids and radiotherapy an urgent consideration. Other factors such as age, presence of co-morbid medical conditions, functional status, and tumor androgensensitivity are important to the patient's overall cancer prognosis

• Question 613:

  A 72-year-old man with a diagnosis of prostate cancer was recently seen in the clinic for restaging and reevaluation. His bone scan showed development of widespread osseous metastases and his PSA was rising. He was started on leuprolide acetate, a gonadotropin releasing-hormone (GnRH) agonist. He now returns to the clinic complaining of new severe mid-thoracic back pain, which is worse with recumbency and worse with Valsalva maneuver. He also reports that he has a brief but intense electric shock sensation in his lower extremities when he bends over to tie his shoes. On physical exam, he had localized tenderness over the mid-thoracic spine, but his motor strength, sensation, and deep tendon reflexes are all intact.

  What is the most appropriate next step?

  A. Obtain an MRI of the thoracic spine.

  B. Refer for neurosurgical evaluation.

  C. Initiate radiation therapy to the affected thoracic spine.

  D. Start the patient on scheduled narcotics for relief of the back pain and follow up in 1 week.

  E. Stop the leuprolide and schedule the patient to return to clinic in 1 week for re-evaluation.

  Correct Answer: A Section: (none)

  Explanation:

  The patient has symptoms of spinal cord compression and needs an urgent MRI to establish the diagnosis. Spinal cord compression usually develops when patients have metastases to the vertebral body with epidural extension of the tumor, displacing the underlying thecal sac, and causing cord edema and injury. Patients with cord compression usually experience new or worsening pain symptoms days or weeks before the development of motor weakness below the level of compression. Loss of sensation and loss of bowel or bladder control occur even later. Clues that the pain symptoms may represent cord injury include pain that is worse with recumbency or Valsalva and the occurrence of Lhermitte's sign, an electric sensation down the back and into the extremities with extension or flexion of the neck or spine.

  Initiation of therapy, such as radiation therapy or neurosurgical intervention, might be necessary later but would be premature before the diagnosis is established with an imaging study. If the patient's history or physical exam suggests spinal cord compression, initiation of corticosteroids should be started immediately while diagnostic imaging is pending. Pain control with adequate narcotic analgesia is important and may be instituted while the appropriate diagnostic studies are being obtained. Delay of 1 week would be inappropriate due to the urgent nature of the problem and risk of neurological compromise. The patient's neurological status at the time of diagnosis is the most important prognostic factor: 7580% of patients who are ambulatory at the time of diagnosis will retain locomotion. But, if already paraplegic, only 10% will regain the ability to walk. While this patient appeared neurologically intact, the development of neurological deficits can progress over a period of days, making rapid diagnosis and institution of appropriate therapy such as corticosteroids and radiotherapy an urgent consideration. Other factors such as age, presence of co-morbid medical conditions, functional status, and tumor androgensensitivity are important to the patient's overall cancer prognosis.

• Question 614:

  A54-year-old man without significant past medical history presents to his primary care physician complaining of epigastric discomfort and early satiety. He subsequently undergoes an endoscopic procedure revealing an ulcerated mucosal lesion. The biopsy of this lesion is interpreted as a well-differentiated lymphoma.

  Which of the following statements regarding his treatment and prognosis is most accurate?

  A. His prognosis is poorer than if he were diagnosed with a gastric adenocarcinoma.

  B. This lymphoma is not associated with Helicobacter pylori infection.

  C. Antibiotic therapy may induce regression of the lesion in the majority of cases.

  D. Treatment will not offer curative potential, so he should be referred for hospice care.

  E. Gastric resection is recommended for well-differentiated, bbut not higher grade, lymphomas.

  Correct Answer: A Section: (none)

  Explanation:

  Although gastric lymphomas are less common than adenocarcinomas, they are much more treatable with a more favorable prognosis. Gastric lymphomas, especially well-differentiated mucosa-associated lymphoid tissue (MALT), are associated with Helicobacter pylori infection, and antibiotic therapy to eradicate H. pylori has been associated with regression of 75% of such tumors. Higher-grade gastric lymphomas may require chemotherapy with a standard regimen, such as CHOP, and consideration for surgical resection with curative intent.

• Question 615:

  Which of the following risk factors has the strongest association with the development of malignant melanoma?

  A. dark skin and hair color with tendency to tan easily and not to burn easily

  B. personal history of sunburn, especially early in life

  C. pigmented lesion with asymmetric irregular borders, color variegation, and diameter 8 mm

  D. family history of non-melanoma skin cancer

  E. development of actinic keratosis

  Correct Answer: C Section: (none)

  Explanation: History of excess sun exposure and sunburn early in life is associated with increased incidence of skin cancers, including melanoma, but the highest risk would be the development of a suspicious pigmented lesion. Clinicians can be guided by the "ABCD" rules: asymmetry, irregular borders, color variegation within the same lesion, and diameter >6 mm. Other risk factors for melanoma would include fair skin and hair with tendency to burn easily and a family history of melanoma. Actinic keratoses are premalignant lesions, but can develop into cutaneous squamous cell malignancies, not melanoma.

• Question 616:

  A 32-year-old man comes to the office for his annual checkup. He is asymptomatic and his physical exam is normal. He reports that his father died of colon cancer at age 46 and his older brother was recently diagnosed with colon cancer at age 37. His paternal aunt was previously diagnosed and treated for endometrial cancer. He is concerned about his family history of malignancy and wants to discuss cancer screening.

  What would be the most appropriate recommendation at this time?

  A. flexible sigmoidoscopy

  B. fecal occult blood testing, with referral for endoscopy if positive

  C. screening colonoscopy

  D. screening colonoscopy starting at age 50

  E. prophylactic colectomy

  Correct Answer: C Section: (none)

  Explanation:

  The patient appears to be at risk for hereditaty nonpolyposis colon cancer (HNPCC) or Lynch syndrome. This autosomally dominant inherited cancer predisposition is characterized by colorectal cancer involving at least two generations, with one or more cases being diagnosed before age 50, and patients may have multiple primary cancers (affected women often also have endometrial or ovarian cancer). It is recommended that HNPCC family members undergo screening colonoscopy every two years beginning at age 25. The colon cancers in HNPCC often involve the proximal colon, so flexible sigmoidoscopy would be an insufficient tool for screening the at-risk bowel. HNPCC should be differentiated from familial adenomatous polyposis (FAP), another inherited colon cancer predisposition. This wellstudied and described autosomal dominant inherited condition is much less common than HNPCC. Affected patients develop thousands of adenomatous premalignant polyps, which are generally evenly distributed from cecum to anus and usually become evident between puberty and age 25. Because the polyps are so widespread and evenly distributed, proctosigmoidoscopy is usually a sufficient screening procedure for at-risk family members. When diagnosed with FAP, it is recommended that patients under prophylactic colectomy. If not treated surgically, almost all patients will develop colorectal cancer by age 40. Colonoscopy beginning at age 50 would be recommended for persons at average risk for colon cancer.

• Question 617:

  An 82-year-old woman schedules an appointment to see you for neck and back pain. At age 50, she had an L4-L5 diskectomy and laminectomy. She also has long-standing hypothyroidism for which she takes levothyroxine 0.1 mg daily. Over the past few months, she has become more fatigued and describes pain in both of her arms, her low back, and the front of her thighs. She notes that the tops of her shoulders are also achy. She decided to call for an appointment because of worsening headache. She tells you that she has an appointment later this afternoon with her ophthalmologist, because she noticed some flickering of the vision in her left eye. Upon further questioning, she does acknowledge that she has cut her telephone conversation short with her daughter because her jaw begins to ache if she talks too long. Physical examination shows that she has normal vital signs. She has diffuse scalp tenderness. The oral mucosa is normal without aphthous ulcers and the salivary pool is normal. Her pupils are equal, round, and reactive to light and accommodation, and extraocular muscles are intact. The funduscopic examination appears normal for her age. Neck motion is slightly reduced to lateral flexion and rotation. Her trapezii are tender to palpation, but there is no significant loss of range of motion in her shoulders. Her supraspinatus and infraspinatus tendons appear intact. Her quadriceps are mildly tender, but her gastrocnemius muscles are normal. Her strength is normal for age. Her reflexes are normal and symmetrical.

  Which of the following should be done next?

  A. start 80 mg prednisone daily

  B. start ibuprofen and refer for a temporal artery biopsy

  C. trigger point injections of triamcinolone in the trapezius muscles

  D. stat MRI/MRA of the head

  E. no treatment until after she is evaluated by the ophthalmologist and a rheumatologist

  Correct Answer: A Section: (none)

  Explanation:

  The diagnosis is almost certainly temporal arteritis. Age over 70, headache with scalp tenderness, jaw claudication, and visual disturbance would suggest the diagnosis even if the sedimentation rate came back within the normal range. Since the patient's supraspinatus and infraspinatus strength are normal, complete rotator cuff tear seems unlikely. Rotator cuff tears would also not explain the leg component. Osteoarthritis of the neck and back could explain many of her clinical features, particularly if spinal stenosis is present, but would not account for the jaw claudication or the headaches with scalp tenderness. Many patients with temporal arteritis have features of polymyalgia rheumatica, but in this case, temporal arteritis is the best working diagnosis. Temporal arteritis is one of the few unequivocal rheumatic disease emergencies. The patient should be given large doses of prednisone immediately. An ESR should be obtained, but as noted above, even a normal study would not prevent the prednisone from being prescribed at this point. You should also contact the ophthalmologist because there can be retinal clues not picked up on standard office funduscopy. In addition, many ophthalmologists now will do the temporal artery biopsy in their patients. This is a very reasonable next step for the patient and will unequivocally establish the diagnosis.

  Temporal arteritis may have skip lesions, and thus, a fairly significant length of the temporal artery should be taken by the surgeon. MRI of the brain, even with MRA, will not help establish a diagnosis of temporal arteritis and will needlessly delay diagnosis, possibly causing the patient to lose vision.

• Question 618:

  An 82-year-old woman schedules an appointment to see you for neck and back pain. At age 50, she had an L4-L5 diskectomy and laminectomy. She also has long-standing hypothyroidism for which she takes levothyroxine 0.1 mg daily. Over the past few months, she has become more fatigued and describes pain in both of her arms, her low back, and the front of her thighs. She notes that the tops of her shoulders are also achy. She decided to call for an appointment because of worsening headache. She tells you that she has an appointment later this afternoon with her ophthalmologist, because she noticed some flickering of the vision in her left eye. Upon further questioning, she does acknowledge that she has cut her telephone conversation short with her daughter because her jaw begins to ache if she talks too long. Physical examination shows that she has normal vital signs. She has diffuse scalp tenderness. The oral mucosa is normal without aphthous ulcers and the salivary pool is normal. Her pupils are equal, round, and reactive to light and accommodation, and extraocular muscles are intact. The funduscopic examination appears normal for her age. Neck motion is slightly reduced to lateral flexion and rotation. Her trapezii are tender to palpation, but there is no significant loss of range of motion in her shoulders. Her supraspinatus and infraspinatus tendons appear intact. Her quadriceps are mildly tender, but her gastrocnemius muscles are normal. Her strength is normal for age. Her reflexes are normal and symmetrical.

  The most likely diagnosis is which of the following?

  A. polymyalgia rheumatica

  B. osteoarthritis of the cervical spine

  C. osteoarthritis of the lumbar spine

  D. bilateral rotator cuff tears

  E. temporal arteritis

  Correct Answer: E Section: (none)

  Explanation: The diagnosis is almost certainly temporal arteritis. Age over 70, headache with scalp tenderness, jaw claudication, and visual disturbance would suggest the diagnosis even if the sedimentation rate came back within the normal range. Since the patient's supraspinatus and infraspinatus strength are normal, complete rotator cuff tear seems unlikely. Rotator cuff tears would also not explain the leg component. Osteoarthritis of the neck and back could explain many of her clinical features, particularly if spinal stenosis is present, but would not account for the jaw claudication or the headaches with scalp tenderness. Many patients with temporal arteritis have features of polymyalgia rheumatica, but in this case, temporal arteritis is the best working diagnosis. Temporal arteritis is one of the few unequivocal rheumatic disease emergencies. The patient should be given large doses of prednisone immediately. An ESR should be obtained, but as noted above, even a normal study would not prevent the prednisone from being prescribed at this point. You should also contact the ophthalmologist because there can be retinal clues not picked up on standard office funduscopy. In addition, many ophthalmologists now will do the temporal artery biopsy in their patients. This is a very reasonable next step for the patient and will unequivocally establish the diagnosis.

  Temporal arteritis may have skip lesions, and thus, a fairly significant length of the temporal artery should be taken by the surgeon. MRI of the brain, even with MRA, will not help establish a diagnosis of temporal arteritis and will needlessly delay diagnosis, possibly causing the patient to lose vision.

• Question 619:

  A 35-year-old woman presents to your office complaining of fatigue and global achiness. She states that she has "not been myself" since she developed a bad whiplash after a motor vehicle accident. Her health has otherwise been good. About 3 years ago, she saw a cardiologist for chest pain. A full evaluation ensued including heart catheterization that showed no coronary disease, although her cholesterol levels were elevated and a statin was prescribed. She sleeps poorly and notes that she has gained a considerable amount of weight. She has seen a gastroenterologist who has told her that her abdominal pain and alternating constipation and diarrhea are because of irritable bowel syndrome. Physical examination shows that her height is 5 ft 2 in. and her weight is 240 lb. Blood pressure is 126/78. Pulse is 86 and regular. Heart and lung examinations are completely normal. Her pharynx is normal and she has no lymphadenopathy. Abdominal examination shows diffuse mild tenderness, but no masses, rebound, guarding, or organomegaly. Rectal and pelvic examinations are normal. Muscular strength is 4/5 distally and proximally, but there is a considerable give way secondary to pain. She is tender bilaterally at the occiput across the trapezius, iliac crest at the greater trochanteric, anserine bursae bilaterally, and at the second intercostal space bilaterally.

  In this patient, which of the following conditions may also be exacerbating her symptoms?

  A. sleep apnea

  B. hyperthyroidism

  C. RA

  D. celiac sprue

  E. medication side effect

  Correct Answer: A Section: (none)

  Explanation:

  The most likely diagnosis in this case is fibromyalgia. Occasionally, hypothyroidism can present in this way,

  and a low-grade myopathy can create many of these symptoms. A reasonable workup would include

  chemistries, TSH, and CPK. The usefulness of Epstein-Barr virus titers in this case is minimal.

  Epidemiologic studies reveal that about 90% of Americans over the age of 20 have been exposed to

  Epstein-Barr virus even if they never had a clinical scenario of mononucleosis. Your physical examination

  did not show any question of acute infectious mononucleosis. Findings of elevated IgG antibodies to Epstein-Barr virus would only reveal the fact that she has had the disease in the past. Absent titers might assure you that there was no evidence of a previous infection, but it is unclear how that would help you sort out the current situation.

• Question 620:

  A 35-year-old woman presents to your office complaining of fatigue and global achiness. She states that she has "not been myself" since she developed a bad whiplash after a motor vehicle accident. Her health has otherwise been good. About 3 years ago, she saw a cardiologist for chest pain. A full evaluation ensued including heart catheterization that showed no coronary disease, although her cholesterol levels were elevated and a statin was prescribed. She sleeps poorly and notes that she has gained a considerable amount of weight. She has seen a gastroenterologist who has told her that her abdominal pain and alternating constipation and diarrhea are because of irritable bowel syndrome. Physical examination shows that her height is 5 ft 2 in. and her weight is 240 lb. Blood pressure is 126/78. Pulse is 86 and regular. Heart and lung examinations are completely normal. Her pharynx is normal and she has no lymphadenopathy. Abdominal examination shows diffuse mild tenderness, but no masses, rebound, guarding, or organomegaly. Rectal and pelvic examinations are normal. Muscular strength is 4/5 distally and proximally, but there is a considerable give way secondary to pain. She is tender bilaterally at the occiput across the trapezius, iliac crest at the greater trochanteric, anserine bursae bilaterally, and at the second intercostal space bilaterally.

  Reasonable initial evaluations would include which of the following?

  A. electromyogram with nerve conduction studies

  B. muscle biopsy

  C. TSH

  D. Epstein-Barr virus titers

  E. cortisol level

  Correct Answer: C Section: (none)

  Explanation:

  The most likely diagnosis in this case is fibromyalgia. Occasionally, hypothyroidism can present in this way, and a low-grade myopathy can create many of these symptoms. A reasonable workup would include chemistries, TSH, and CPK. The usefulness of Epstein-Barr virus titers in this case is minimal. Epidemiologic studies reveal that about 90% of Americans over the age of 20 have been exposed to Epstein-Barr virus even if they never had a clinical scenario of mononucleosis. Your physical examination did not show any question of acute infectious mononucleosis. Findings of elevated IgG antibodies to Epstein-Barr virus would only reveal the fact that she has had the disease in the past. Absent titers might assure you that there was no evidence of a previous infection, but it is unclear how that would help you sort out the current situation.