USMLE USMLE Certifications USMLE-STEP-2 Questions & Answers

• Question 501:

  An 8-year-old African American boy is brought in for evaluation of a mass on the scalp. On examination, he is afebrile and nontoxic. There is a boggy mass on his scalp with alopecia. His posterior cervical lymph nodes are enlarged but nontender. Which of the following is the most appropriate treatment?

  A. incision and drainage

  B. oral amoxicillin

  C. IV naficillin

  D. selenium sulfide shampoo twice a week

  E. oral griseofulvin and selenium sulfide shampoo twice weekly

  Correct Answer: E

  A tender, boggy mass on the scalp is most likely to be a kerion. This is an inflammatory form of tinea capitis. Tinea capitis is more common in African American children and is the most common cause of alopecia in children. In the United States, a majority of cases are caused by Trichophyton tonsurans; Microsporum canis may also be involved. Tinea capitis may present with diffuse scaling, a black dot form, and as the inflammatory form--kerion. The recommended treatment is 812 weeks of oral griseofulvin. Shampooing with selenium sulfide shampoo is a helpful adjunctive therapy which decreases spore shedding. Topical therapy alone is ineffective. Incision and drainage or antibiotic therapy are not recommended in treatment of tinea capitis.

• Question 502:

  A2-year-old girl has severe dental caries of the upper and lower incisors. Her teeth are brushed twice daily with a small amount of fluoride-containing toothpaste. What is the feeding practice most likely to result in this pattern of dental caries?

  A. drinking juice from a cup at snack time

  B. drinking juice from a bottle at snack time

  C. drinking milk from a bottle at meal time

  D. prolonged breast-feeding beyond the first year

  E. drinking a bottle of juice in bed

  Correct Answer: E

  Organic acids produced by bacterial fermentation lower the pH of dental plaque causing demineralization and caries of the adjacent tooth. Nursing bottle caries is a pattern of caries involving the upper and lower incisors. It occurs because of prolonged contact of the tooth to a sugar-containing liquid (juice or milk). This is more likely to occur with overnight exposure or with use of a bottle. Asimilar pattern of caries may rarely occur with breast-fed babies who feed through the night. Cup feeding or drinks given during mealtimes are less likely to cause prolonged contact to the teeth.

• Question 503:

  A17-year-old girl comes to the clinic with several weeks of joint pain and rash. The joint pain is most prominent in the hands. She states that the pain is most severe in the morning and tends to improve over the day. She has noted some swelling of her fingers. She has also had a rash on her face that becomes more prominent when she is outdoors. She states that sunlight tends to bother her eyes. On further questioning, she states that she has not felt well for several months. She has had intermittent fever, has been more tired than usual, and has lost weight although she has not been restricting her diet. On physical examination, she looks tired. She has lost 5 lbs since her last visit 1 year ago. She has an erythematous rash on her cheeks. She has several shallow ulcers in her mouth. She has fusiform swelling of her fingers and pain with movement of her fingers.

  Which of the following is the most likelydiagnosis?

  A. systemic lupus erythematosus (SLE)

  B. dermatomyositis

  C. juvenile rheumatoid arthritis

  D. rheumatic fever

  E. Lyme disease

  Correct Answer: A

  SLE is an autoimmune disorder that affects multiple organs. The diagnosis is based on the presence of four or more major criteria. These include malar rash, oral ulcers, arthritis, and photosensitivity. This patient has all of these symptoms, as well as the systemic symptoms often seen at presentation. The disorder is predominately a disease of women and, in the pediatric population, is a disease of adolescence. Chronic renal disease is an important and common cause of morbidity and mortality among patients with SLE.

• Question 504:

  A 12-year-old boy comes to the clinic for a sports physical. He is new to your practice. He comes with his foster mother, who states that he was recently placed in her care because of his mother's problems with drug abuse. Although a complete medical history is not available, she knows that he has not received regular care. He does not have any chronic medical problems. She also knows that his father died of heart disease when he was 35. On physical examination, the boy's height is greater than the 95th percentile. His arm span exceeds his height.

  As you continue your physical examination, you remember that congenital heart disease is common in this particular syndrome. Which of the following is the most likely congenital heart defect in patients with this syndrome?

  A. supravalvular aortic stenosis

  B. AV canal defects

  C. coarctation of the aorta

  D. pulmonary valvular stenosis

  E. mitral valve prolapse

  Correct Answer: E

  Marfan syndrome is associated with mitralvalve prolapse and aortic root dilatation.

• Question 505:

  An 8-year-old girl presents for a checkup. She is new to your practice. The mother states that she has always been small for her age; otherwise, she has been well. She is short and has a height age of 4 years, 4 months. You note some abnormalities in her general appearance as shown in the figure.

  

  Which of the following is the most likely diagnosis?

  A. Marfan syndrome

  B. Noonan syndrome

  C. trisomy 21

  D. Turner syndrome

  E. Williams syndrome

  Correct Answer: D

  Patients with Turner syndrome have a 45,X karyotype. The classic physical features are illustrated in this case. Patients have short stature, a webbed neck, ptosis, triangular faces, prominent brow, hypertelorism, low-set ears, and pectus excavatum

• Question 506:

  A 12-year-old boy comes to the clinic for a sports physical. He is new to your practice. He comes with his foster mother, who states that he was recently placed in her care because of his mother's problems with drug abuse. Although a complete medical history is not available, she knows that he has not received regular care. He does not have any chronic medical problems. She also knows that his father died of heart disease when he was 35. On physical examination, the boy's height is greater than the 95th percentile. His arm span exceeds his height. Which of the following is the most likely cause of his tall stature?

  A. Ehlers-Danlos syndrome

  B. Kleinfelter syndrome

  C. Marfan syndrome

  D. Noonan syndrome E. Williams syndrome

  Correct Answer: C

  Marfan syndrome is a genetic disorder of connective tissue. It is transmitted in an autosomal dominant manner. Patients have tall stature and skeletal disproportion, where the arm span exceeds the height. Other important clinical features include subluxation of the ocular lens which occurs in 5080% of patients. Progressive dilatation of the aortic root and ascending aorta can lead to dissection or rupture.

• Question 507:

  A 10-year-old boy comes to your office in the winter with a sore throat he has had for 2 days. In addition, he has had fever, headache, and abdominal pain. He does not have any allergies to medications. On examination, he has a temperature of 38.6°C, an ery thematous pharynx, and tender cervical adenopathy. Arapid screening test for group Astreptococcus is performed and is positive. Which of the following would be the most appropriate antimicrobial agent?

  The same child returns to your office the next day. He has taken the medication you prescribed. He is feeling a little better. His fever has resolved, but he has developed a rash. His examination is unchanged, except that he is afebrile and has a fine, papular rash over his body, which is accentuated in his axilla and groin.

  Which of the following is the most likely cause of his rash?

  A. allergic reaction to the antibiotic

  B. rash from the antibiotic seen in patients with mononucleosis

  C. scarlet fever

  D. serum sickness

  E. viral exanthem typical of enterovirus

  Correct Answer: C

  Scarlet fever is caused by toxins made by group A Streptococci. It is usually seen in patients with strep throat. The rash is popular and described as sandpaper like. Sometimes it is easier to feel it than to see it. An allergic rash would be urticarial. More than 80% of patients with EBV infection develop a maculopapular rash if given amoxicillin. This patient's clinical course is not typical for EBV which presents more gradually, and patients often have posterior cervical adenopathy and splenomegaly. Patients with serum sickness often have urticarial rashes, sometimes progressing to angioedema. They may also have arthritis, myalgias, and lymphadenopathy. The rash in enteroviral infections is typically macular.

• Question 508:

  A 10-year-old boy comes to your office in the winter with a sore throat he has had for 2 days. In addition, he has had fever, headache, and abdominal pain. He does not have any allergies to medications. On examination, he has a temperature of 38.6°C, an ery thematous pharynx, and tender cervical adenopathy. Arapid screening test for group Astreptococcus is performed and is positive. Which of the following would be the most appropriate antimicrobial agent?

  A. erythromycin

  B. penicillin

  C. trimethoprim-sulfamethoxazole

  D. azithromycin

  E. cefaclor

  Correct Answer: B

  Penicillin remains the drug of choice for treatment of streptococcal pharyngitis. Amoxicillin, macrolides, and cephalosporins are acceptable alternatives.

• Question 509:

  An 11-month-old girl presents to your office with a fever of 39°C she has had for 2 days. She has also vomited frequently and had decreased fluid intake. She looked tired and ill but on examination, had no apparent source of infection. She appeared to be 510% dehydrated.

  After the infection has been treated, which one of the following tests should be considered ?

  A. no tests are needed

  B. renal ultrasound

  C. voiding cystourethrogram (VCUG)

  D. renal ultrasound and a VCUG

  E. radionucleotide renal scan

  Correct Answer: D

  Urine for urinalysis and culture must be properly obtained. Catheterization is the most reliable method of the choices offered. Suprapubic tap is considered the "gold-standard" but is not always technically feasible, especially in an outpatient office setting. Amidstream, clean catch specimen would be acceptable in an older, toilet-trained child. "Bagged" specimens are not recommended because of possible skin or fecal contamination of the specimen. Similarly, obtaining a sample from a diaper or potty would be unacceptable. Urinalysis includes dipstick method and microscopic examination. Leukocyte esterase (an enzyme in WBC) and nitrites suggest probable infection. Microscopic analysis of unspun urine for WBC (>10/ highpower field) or bacteria is also predictive of infection. RBCs are often present in a UTI. The patient is vomiting and dehydrated; this may indicate possible pyelonephritis. The most appropriate course would be IV hydration and empiric treatment with antibiotics (ceftriaxone) while awaiting cultures. Children with pyelonephritis are at increased risk of renal scarring, especially younger children, and should be treated early. E. coli is the most common organism cultured; others include Proteus, Klebsiella, S saprophyticus, and Enterococcus. The occurrence of a UTI in a girl under age 35 years and in a boy of any age may be a marker for an underlying congenital anatomic abnormality, in particular, vesicourethral reflux. Radiologic investigation with renal ultrasound and VCUG is recommended

• Question 510:

  An 11-month-old girl presents to your office with a fever of 39°C she has had for 2 days. She has also vomited frequently and had decreased fluid intake. She looked tired and ill but on examination, had no apparent source of infection. She appeared to be 510% dehydrated.

  Her urine culture is positive at 24 hours. Which of the following is the most likely organism?

  A. Klebsiella

  B. Escherichia coli

  C. Staphylococcus saprophyticus

  D. Proteus

  E. Enterococcus

  Correct Answer: B

  Urine for urinalysis and culture must be properly obtained. Catheterization is the most reliable method of the choices offered. Suprapubic tap is considered the "gold-standard" but is not always technically feasible, especially in an outpatient office setting. Amidstream, clean catch specimen would be acceptable in an older, toilet-trained child. "Bagged" specimens are not recommended because of possible skin or fecal contamination of the specimen. Similarly, obtaining a sample from a diaper or potty would be unacceptable. Urinalysis includes dipstick method and microscopic examination. Leukocyte esterase (an enzyme in WBC) and nitrites suggest probable infection. Microscopic analysis of unspun urine for WBC (>10/ highpower field) or bacteria is also predictive of infection. RBCs are often present in a UTI. The patient is vomiting and dehydrated; this may indicate possible pyelonephritis. The most appropriate course would be IV hydration and empiric treatment with antibiotics (ceftriaxone) while awaiting cultures. Children with pyelonephritis are at increased risk of renal scarring, especially younger children, and should be treated early. E. coli is the most common organism cultured; others include Proteus, Klebsiella, S saprophyticus, and Enterococcus. The occurrence of a UTI in a girl under age 35 years and in a boy of any age may be a marker for an underlying congenital anatomic abnormality, in particular, vesicourethral reflux. Radiologic investigation with renal ultrasound and VCUG is recommended