USMLE USMLE Certifications USMLE-STEP-2 Questions & Answers

• Question 441:

  Children with sickle cell disease are at risk for certain conditions with characteristic presentation. Match the clinical scenario with the syndrome.

  An 8-month-old patient with sickle cell disease presents with a 2-day history of painful, swollen fingers and toes.

  A. acute chest syndrome

  B. acute splenic sequestration

  C. aplastic crisis

  D. hand-foot syndrome

  E. Salmonella osteomyelitis

  F. vasoocclusive crisis

  Correct Answer: D

  Acute sickle dactylitis or hand-foot syndrome is often the earliest clinical syndrome seen in children with sickle cell anemia. There is painful, symmetrical swelling of the hands and feet. Roentgenograms usually reveal bony destruction only in the later phase, 12 weeks later.

• Question 442:

  A 7-month-old patient presents with a history of 3 days of fever to 104°F, which resolved the same day that

  an exanthem erupted. The exanthema is prominent on the neck and trunk. It is macular, with discrete

  lesions 35 mm in diameter.

  Which of the following is the most likely diagnosis?

  A. erythema infectiosum

  B. measles

  C. roseola infantum

  D. rubella

  E. scarlet fever

  Correct Answer: C

  Roseola infantum, or sixth disease, is a common acute illness of young children. Human herpesvirus 6 is the most common etiologic agent. The rash of erythema infectiosum presents initially on the face. It is intensely red with a "slapped-cheek" appearance. Rubella and measles are not commonly seen because of routine vaccination. The rash of scarlet fever is on the trunk and is described as sandpaper like.

• Question 443:

  A3-year-old male presents after having a tonicclonic seizure lasting about 1 minute. On examination, the child now has no nuerologic abnormalities. He has a temperature of 40.3°C and has an obvious otitis media on the left but no other abnormalities on physical examination. You correctly counsel the family with which one of the following statements?

  A. The child will need hospitalization, a lumbar puncture, and antibiotics.

  B. An EEG and CNS imaging must be done.

  C. Anticonvulsants must be stated and continued for 6 months.

  D. There is a slight increase in risk for development of epilepsy.

  E. The child must be monitored carefully for long-term neurologic damage.

  Correct Answer: D

  Simple febrile seizures are common in children between ages 6 months and 5 years. They are usually brief, with bilateral clonic or tonicclonic movement. They have a 30% likelihood of recurrence. The investigation should include a search for the cause of the fever, usually a viral infection, UTI, or following immunization. A lumbar puncture must be performed if there is suspicion of an intracranial infection and when features of the seizure suggest a focal or lateralized seizure. In these situations, EEG and imaging may also be considered. However, in most children with uncomplicated febrile seizures, these procedures are unnecessary. There is an increased risk for developing epilepsy in later life, as high as 7% in a study with mean followup of 18 years. When risk factors are present, the incidence of epilepsy rises to 49%. Risk factors include prior neurologic abnormality, prolonged seizures (>30 minutes), focal or lateralized seizure, and repeated seizure within 24 hours.

• Question 444:

  A 2-week-old infant presents with hepatosplenomegaly and a thick, purulent, bloody nasal discharge. Coppery, oval, maculopapular skin lesions are present in an acral distribution. The neurologic examination is normal, including head circumference. Which of the following is the most likely cause of this congenital infection?

  A. cytomegalovirus (CMV)

  B. HSV

  C. GBS

  D. T. gondii

  E. T. pallidum

  Correct Answer: E

  Transplacental passage of T. pallidum causes widespread disease in the fetus. Organs most severely affected include brain, bone, liver, and lung. Hepatosplenomegaly, rare in neonates with GBS or HSV infections, occurs in 90% of neonates with congenital syphilis. Mucocutaneous lesions produce a persistent, purulent, often bloody nasal discharge which is termed snuffles. This nasal discharge is highly infectious. Skin rash is uncommon in CMV and GBS infections. The acral distribution described is characteristic of congenital syphilis. Congenital toxoplasmosis characteristically presents with neurologic abnormalities. The classic triad includes hydrocephalus, chorioretinitis, and diffuse intracranial calcifications

• Question 445:

  Which of the following is the most appropriate evaluative procedure for an otherwise normal 7-day-old boy with perineal hypospadias?

  A. renal ultrasonography

  B. serum creatinine determination

  C. cystography

  D. circumcision

  E. intravenous pyelography (IVP)

  Correct Answer: A

  Children with more severe cases of hypospadias have an increased incidence of concomitant urinary tract anomalies and require careful evaluation. Ultrasonography is a safe and noninvasive procedure that is sensitive in the diagnosis of neonatal urinary tract pathology. It is a better choice than either IVP or cystography which use contrast media and radiation. Serum creatinine determinations are a measure of renal function and are unnecessary in an otherwise healthy child. Circumcision is not indicated in children with hypospadias. In fact, it may be contraindicated in cases of second- or third-degree hypospadias, in which the prepuce can be used to construct an absent distal segment of urethra.

• Question 446:

  A 2-week-old Caucasian male presents with constipation since birth. He was born full term via a normal vaginal delivery. He did not pass meconium till his 3rd day of life, after he was given a glycerin suppository. He has since stooled every 34 days, only with the help of a suppository. The stools are pellet like. He has had increasing abdominal distention. On rectal examination, tone appears normal and the ampulla contains no stool.

  Which of the following is the most likely cause?

  A. cystic fibrosis

  B. Hirschprung disease

  C. anal stenosis

  D. functional constipation

  E. hypothyroidism

  Correct Answer: B

  Hirschprung disease or congenital aganglionic megacolon is the most common cause of lower intestinal obstruction in neonates. Incidence is 1/5000 live births; males are four times as likely to be affected. Initial presentation is with delayed passage of meconium. Failure to pass stools leads to dilation of proximal bowel and abdominal distention. Diagnosis is by barium enema which reveals a small-caliber rectum with transition in the rectosigmoid to a dilated, obstructed proximal colon. Diagnosis is confirmed by biopsy. Meconium plugs and meconium ileus are often found in cystic fibrosis, which should be excluded. Anal stenosis may be diagnosed by rectal examination or endoscopy. Functional constipation usually presents in children older than 2 years. There may be some abdominal distention; anal tone is usually normal, and the rectal ampulla is often full of stool. Congenital hypothyroidism may present with constipation; neonatal screening tests usually allow early diagnosis. Other features include feeding difficulties, prolonged jaundice, sluggishness, a large abdomen with umbilical hernia, subnormal body temperature, myxedema, and developmental delay.

• Question 447:

  A4-year-old child with grade III vesicoureteral reflux has recurrent UTIs despite adequate antibiotic prophylaxis. Which of the following is the most appropriate next step in the treatment of this patient?

  A. IV antibiotic treatment for 2 weeks

  B. repeat renal scan

  C. renal arteriogram

  D. antireflux surgery

  E. addition of vitamin C (ascorbic acid) tothe treatment regimen

  Correct Answer: D

  Vesicoureteral reflux is the most common anatomic abnormality associated with recurrent UTI in children. Many cases of reflux are the result of an inadequate length of submucosal ureter immediately proximal to its opening into the bladder lumen, a condition that sometimes requires surgical correction. However, in other children, reflux often seems to result from the direct effects of infection on ureteral tone and peristalsis. Thus, many children may outgrow mild degrees of reflux if they are maintained on prophylactic antibiotics. Moderate-to-severe degrees of reflux frequently require surgery. Failure of adequate antibiotic treatment to prevent infection is also a prime indication for surgery. Repeating an IVP or performing a renal arteriogram on an already diagnosed case would not be useful, although a radionuclide scan may be very helpful to determine the present degree of reflux with a minimum of radiation exposure. Vitamin C, although reportedly useful in acidifying the urine to help prevent infection, does not enhance adequate antibiotic prophylaxis. IV antibiotics would be necessary only if oral antibiotics were not successful in eradicating infection.

• Question 448:

  A 2-year-old boy presents with refusal to use his right arm for 1 day. He is otherwise well.His mother states

  she pulled upward on his arm the previous evening to keep him from tripping down the stairs.

  Which of the following is the most likely diagnosis?

  A. Colles fracture

  B. fractured clavicle

  C. greenstick fracture of the humerus

  D. rotator cuff injury

  E. subluxation of the radial head

  Correct Answer: E

  Nursemaid's elbow, or subluxation of the radial head, occurs in children following longitudinal traction on a pronated extended elbow. When attempting to restrain a child, an uninformed caretaker may jerk on a child's upper extremity. The result is a painful subluxed elbow that is easily reduced by simultaneous flexion and supination of the forearm.

• Question 449:

  A 4-year-old child presents with an enlarged submandibular node that is 4 cm in diameter, nontender, and not fluctuant. The node has been enlarged for about 4 weeks, and there is no history of fever or contact with any person who was ill. A CBC is normal, and a Mantoux test with 5 tuberculin units of PPD shows 6 mm of induration. Which of the following is the most likely diagnosis?

  A. cat-scratch fever

  B. acute pyogenic lymphadenitis

  C. acute lymphoblastic leukemia

  D. tuberculous lymphadenitis

  E. atypical mycobacteria lymphadenitis

  Correct Answer: E

  Nontuberculous lymphadenitis (atypical mycobacteria) is characterized by nontender lymphadenitis. Affected persons are usually afebrile, and the CBC is usually normal. Unlike tuberculous lymphadenitis, a history of contact with a tuberculous individual is lacking, and the reaction to 5 tuberculin units of PPD is almost always less than 10 mm of induration. Cat-scratch fever is characterized by tender, fluctuating nodes and low-grade fever. Acute lymphadenitis is characterized by tender nodes that may fluctuate. The WBC count is often elevated, and there is frequently a shift to the left on the differential. In addition, the sufferer is often febrile. Acute lymphoblastic leukemia may present as lymphadenitis, but the CBC is usually abnormal, with blasts present on the peripheral smear

• Question 450:

  A2-year-old child is brought to the emergency department with sudden onset of nresponsiveness, miosis, bradycardia, and muscle fasciculations. These findings are most suggestive of poisoning with which of the following?

  A. acetaminophen

  B. organophosphates

  C. salicylates

  D. tricyclic antidepressants

  E. vitamin A

  Correct Answer: B

  Organophosphate poisoning is a leading cause of fatal ingestions of nonpharmaceutical compounds. Common components of insecticides, organophosphates are readily absorbed across skin and mucous membranes. They bind irreversibly to cholinesterase, which results in prolongation of the effects of acetylcholine, centrally and peripherally. Symptoms include muscle fasciculations, paralysis (nicotinic effect) and miosis, salivation, diarrhea, bradycardia, lacrimation (muscarinic effect) and obtundation, seizures, or apnea (central effect). Acetaminophen ingestion can present with vomiting and then later signs of liver failure if it is severe enough. Patients with salicylate overdose present with hypoglycemia, respiratory alkalosis followed by metabolic acidosis, hypokalemia, and mental status changes. Tricyclic antidepressants poisoning causes arrhythmias, mental status changes, and anticholinergic symptoms. Patients with acute vitamin Atoxicity have mental status changes, nausea, and vomiting.