USMLE USMLE Certifications USMLE-STEP-3 Questions & Answers

• Question 431:

  Which of the following conditions usually causes hypoglycemia at birth?

  A. Sturge-Weber syndrome

  B. neurofibromatosis, type 1 (von Recklinghausen disease)

  C. tuberous sclerosis

  D. CHARGE association

  E. Beckwith-Wiedemann syndrome

  Correct Answer: E Section: (none)

  Explanation:

  Of the listed syndromes, only Beckwith Wiedemann syndrome has neonatal hypoglycemia as part of its clinical spectrum. The constellation of macroglossia, hypoglycemia, and visceral organomegaly (hepatosplenomegaly) is a common finding in children with Beckwith-Wiedemann syndrome. The presence of an omphalocele in a newborn would also be concerning for Beckwith-Wiedemann syndrome.

• Question 432:

  A 10-month-old infant has a dysplastic right external ear, some preauricular tags, and a small notch (coloboma) in the iris and lower lid. Which condition does he likely have?

  A. VATER association

  B. neurofibromatosis, type 1 (von Recklinghausen disease)

  C. retinoic embryopathy

  D. CHARGE association

  E. DiGeorge syndrome

  Correct Answer: D Section: (none)

  Explanation:

  The term CHARGE is a mnemonic standing for Coloboma, Heart malformations, Atresia choanae, Retarded (growth and mental),Genital anomalies, and Ear anomalies. The colobomas are usually seen in the iris, but can be seen in the eyelids and the nasolabial folds as well. The heart anomalies of CHARGE association are usually ventricular septal defects and tetralogy of Fallot.

• Question 433:

  While working in the emergency department in the winter, you examine a 3-week-old female infant. The baby is accompanied by her mother and father. They report that the baby has been congested for the past 24 hours. The parents have been taking the infant's temperature rectally and report that it has been normal. The infant was a born at 35 weeks' gestation and was delivered by caesarian due to preeclampsia. On examination, you see a well-appearing infant with a respiratory rate (RR) of 46 and a heart rate (HR) of

  112. The TMs are normal and the lung fields are clear to auscultation. The mother relates that she has had a "cold" for the past few days. The father reports that he smokes, but only outside. As part of your evaluation you perform a nasopharyngeal swab for RSV antigen, which comes back positive. The best course of action for this infant is which of the following?

  A. full sepsis workup with empiric intravenous antibiotic

  B. IM RSV-IVIG administration

  C. admit to the hospital for IV ribavirin for 5 days

  D. admit to the hospital for observation

  E. begin prophylactic oral amoxicillin

  Correct Answer: D Section: (none)

  Explanation: The majority of otherwise healthy infants who get RSV infections will tolerate the course without complications. Some rare complications can occur in infants with risk factors, which include prematurity; cardiac or pulmonary disease or immune system dysfunction. Premature infants are at particular risk for apnea. It is prudent to observe premature infants for apnea in the first few days of their RSV infection. Afull sepsis workup would not be warranted in an otherwise well-appearing, afebrile, infant. RSV-IVIG is not indicated for acute management of RSV infections. Likewise, it is unwarranted to begin antimicrobial therapy without a clear indication.

• Question 434:

  A mildly mentally retarded 9-year-old girl is brought to your office for acne. On examination, she does not actually have acne but has small flesh colored papules along her nasolabial fold. Her past history is significant for having had a first (afebrile) seizure last year. The mother reminds you that she has a faint birthmark on her hip that is pale and becomes more prominent in the summer, when the child's skin tans. Examination of this area reveals a 5-cm oval patch that is hypopigmented. Which condition would she most likely have?

  In evaluating her first seizure, a head CT was performed. Which finding would be most consistent with her diagnosis?

  A. frontal cortical atrophy with dysplastic vessels

  B. periventricular "tubers"

  C. diffuse white matter calcifications

  D. hydrocephalus from aqueductal stenosis

  E. poor gray-white differentiation

  Correct Answer: B Section: (none)

  Explanation:

  Children with tuberous sclerosis (tuberous sclerosis complex, TSC) can develop nasolabial fold angiofibromas (commonly referred to adenoma sebaceum). These can be mistaken for acne in an adolescent and is seen in over 80% of adolescents with TSC. Other cutaneous findings include peri-and subungual fibromas, ash leaf spots (hypomelanocytic macules), and shagreen patches. Skin findings are seen in 75% of cases of tuberous sclerosis. Tuberous sclerosis can also have CNS cortical defects and "tubers," which may be foci of seizure activity. The "tubers" have a classic periventricular distribution. Mental retardation is very common in varying degrees. Sturge-Weber syndrome (also known as leptomeningeal angiomatosis) is a port wine stain, typically with V1 or V2 distribution, with an underlying leptomeningeal blood vessel dysplasia. These dysplastic vessels will typically result in an underlying cortical atrophy. This cortical atrophy can be a nidus for seizures and can be seen on a CT scan of the head. Neurofibromatosis, type 1 is polymorphous neurocutaneous syndrome. The most common findings are café au lait spots, which may be present at birth and worsen during puberty. Beckwith-Wiedemann syndrome and CHARGE association are discussed further in explanations 44 and 45

• Question 435:

  A mildly mentally retarded 9-year-old girl is brought to your office for acne. On examination, she does not actually have acne but has small flesh colored papules along her nasolabial fold. Her past history is significant for having had a first (afebrile) seizure last year. The mother reminds you that she has a faint birthmark on her hip that is pale and becomes more prominent in the summer, when the child's skin tans. Examination of this area reveals a 5-cm oval patch that is hypopigmented. Which condition would she most likely have?

  A. Sturge-Weber syndrome

  B. neurofibromatosis, type 1 (von Recklinghausen disease)

  C. tuberous sclerosis

  D. CHARGE association

  E. Beckwith-Wiedemann syndrome

  Correct Answer: C Section: (none)

  Explanation:

  Children with tuberous sclerosis (tuberous sclerosis complex, TSC) can develop nasolabial fold angiofibromas (commonly referred to adenoma sebaceum). These can be mistaken for acne in an adolescent and is seen in over 80% of adolescents with TSC. Other cutaneous findings include peri-and subungual fibromas, ash leaf spots (hypomelanocytic macules), and shagreen patches. Skin findings are seen in 75% of cases of tuberous sclerosis. Tuberous sclerosis can also have CNS cortical defects and "tubers," which may be foci of seizure activity. The "tubers" have a classic periventricular distribution. Mental retardation is very common in varying degrees. Sturge-Weber syndrome (also known as leptomeningeal angiomatosis) is a port wine stain, typically with V1 or V2 distribution, with an underlying leptomeningeal blood vessel dysplasia. These dysplastic vessels will typically result in an underlying cortical atrophy. This cortical atrophy can be a nidus for seizures and can be seen on a CT scan of the head. Neurofibromatosis, type 1 is polymorphous neurocutaneous syndrome. The most common findings are café au lait spots, which may be present at birth and worsen during puberty. Beckwith-Wiedemann syndrome and CHARGE association are discussed further in explanations 44 and 45.

• Question 436:

  A 4-year-old child is brought to your office because of a sudden onset of irritability, weakness, and pallor. The mother tells you that both of her children have been experiencing episodes of vomiting and diarrhea. Your physical examination reveals a blood pressure of 115/80, dry mucus membranes, petechiae, and diffuse abdominal pain. The following laboratory work is obtained: Urinalysis: microscopic hematuria and proteinuria Blood urea nitrogen (BUN)/creatinine (Cr): 20/1.0 mg/dL Hemoglobin: 7 g/dL Peripheral blood smear: fragmented RBCs Prothrombin time (PT), partial thromboplastin time (PTT): normal Coombs' test: negative

  What is the most likely diagnosis?

  A. ITP

  B. HSP

  C. Evans syndrome

  D. meningococcemia

  E. HUS

  Correct Answer: E Section: (none)

  Explanation:

  HUS is, as the name implies, the combination of a microangiopathic hemolytic anemia and acute renal failure. It is commonly associated with E. coli O157/H7 gastroenteritis. HUS is one of the most common causes of acquired renal failure in children.

• Question 437:

  A well-appearing 6-year-old presents to your office with a chief complaint of bruising. The parents report that the child had a cold 2 weeks ago but completely recovered. The child is sitting on the examining table, in no distress, discussing her favorite cartoons. On examination, you find mucosal bleeding and bruises on the child's arms and chest. You order a complete blood count (CBC) that has the following results: WBC 12,000, hemoglobin 11 g/dL, and a platelet count of 45,000.

  Following your initial evaluation and treatment, you see the child for follow-up in 1 week. She continues to appear well but still has obvious purpura and her platelet count is now 17,000. All other cell lines are normal. Of the options listed below, what is your most appropriate management at this time?

  A. admission to the regional children's hospital for a platelet transfusion

  B. admission to the children's hospital for a splenectomy

  C. reassurance to the parents and close outpatient follow-up

  D. admission to the children's hospital for IVIG and steroids

  E. whole-blood transfusion with several hours of observation to ensure that there is no transfusion reaction

  Correct Answer: D Section: (none)

  Explanation:

  The hallmark of immune (also known as idiopathic) thrombocytopenia purpura (ITP) is the otherwise healthy appearing child with isolated thrombocytopenia. ITP is the most common cause of isolated thrombocytopenia in childhood. It occurs with equal frequency in both boys and girls. The presence of thrombocytopenia in a patient with otherwise normal cell lines, and a normal physical examination is enough to make the diagnosis, so further evaluation, such as a bone marrow biopsy, is unnecessary. Which children to treat and which treatment to use are areas of controversy in the management of ITP. Most acute ITP will resolve spontaneously, so many will recommend observation for children who appear well, are asymptomatic, and have platelet counts above 30,000. Platelet transfusions should be reserved only in the instance of ongoing or imminent bleeding. When a decision is made to treat, usually when the platelet count falls below 20,000, there are several options available. Treatment involves using IVIG, steroids, anti-D immunoglobulins, or combinations thereof. Combinations of medications may work synergistically. Prednisone is often used initially, as it can be given orally and is inexpensive. Typically, it will be tapered over 2 weeks to 3 months. By using combination therapy when needed, splenectomy can be avoided in the vast majority of cases. When it is necessary, it should be delayed, if at all possible, for at least a year after diagnosis.

• Question 438:

  A well-appearing 6-year-old presents to your office with a chief complaint of bruising. The parents report that the child had a cold 2 weeks ago but completely recovered. The child is sitting on the examining table, in no distress, discussing her favorite cartoons. On examination, you find mucosal bleeding and bruises on the child's arms and chest. You order a complete blood count (CBC) that has the following results: WBC 12,000, hemoglobin 11 g/dL, and a platelet count of 45,000.

  After discussing various options with a regional pediatric hematologist and the patient's parents, your most appropriate initial management would be which of the following?

  A. a platelet transfusion at the regional children's hospital

  B. an IM dose of methylprednisolone as an outpatient

  C. reassurance to the parents with close outpatient follow-up

  D. intravenous immunoglobulin (IVIG) at the regional children's hospital

  E. bone marrow biopsy at the regional children's hospital

  Correct Answer: C Section: (none)

  Explanation:

  The hallmark of immune (also known as idiopathic) thrombocytopenia purpura (ITP) is the otherwise healthy appearing child with isolated thrombocytopenia. ITP is the most common cause of isolated thrombocytopenia in childhood. It occurs with equal frequency in both boys and girls. The presence of thrombocytopenia in a patient with otherwise normal cell lines, and a normal physical examination is enough to make the diagnosis, so further evaluation, such as a bone marrow biopsy, is unnecessary. Which children to treat and which treatment to use are areas of controversy in the management of ITP. Most acute ITP will resolve spontaneously, so many will recommend observation for children who appear well, are asymptomatic, and have platelet counts above 30,000. Platelet transfusions should be reserved only in the instance of ongoing or imminent bleeding. When a decision is made to treat, usually when the platelet count falls below 20,000, there are several options available. Treatment involves using IVIG, steroids, anti-D immunoglobulins, or combinations thereof. Combinations of medications may work synergistically. Prednisone is often used initially, as it can be given orally and is inexpensive. Typically, it will be tapered over 2 weeks to 3 months. By using combination therapy when needed, splenectomy can be avoided in the vast majority of cases. When it is necessary, it should be delayed, if at all possible, for at least a year after diagnosis.

• Question 439:

  A well-appearing 6-year-old presents to your office with a chief complaint of bruising. The parents report that the child had a cold 2 weeks ago but completely recovered. The child is sitting on the examining table, in no distress, discussing her favorite cartoons. On examination, you find mucosal bleeding and bruises on the child's arms and chest. You order a complete blood count (CBC) that has the following results: WBC 12,000, hemoglobin 11 g/dL, and a platelet count of 45,000.

  What is the most likely cause of this child's bleeding and bruising?

  A. immune thrombocytopenic purpura (ITP)

  B. Henoch-Schönlein purpura (HSP)

  C. Evans syndrome

  D. meningococcemia E. hemolytic uremic syndrome (HUS)

  Correct Answer: A Section: (none)

  Explanation: The hallmark of immune (also known as idiopathic) thrombocytopenia purpura (ITP) is the otherwise healthy appearing child with isolated thrombocytopenia. ITP is the most common cause of isolated thrombocytopenia in childhood. It occurs with equal frequency in both boys and girls. The presence of thrombocytopenia in a patient with otherwise normal cell lines, and a normal physical examination is enough to make the diagnosis, so further evaluation, such as a bone marrow biopsy, is unnecessary. Which children to treat and which treatment to use are areas of controversy in the management of ITP. Most acute ITP will resolve spontaneously, so many will recommend observation for children who appear well, are asymptomatic, and have platelet counts above 30,000. Platelet transfusions should be reserved only in the instance of ongoing or imminent bleeding. When a decision is made to treat, usually when the platelet count falls below 20,000, there are several options available. Treatment involves using IVIG, steroids, anti-D immunoglobulins, or combinations thereof. Combinations of medications may work synergistically. Prednisone is often used initially, as it can be given orally and is inexpensive. Typically, it will be tapered over 2 weeks to 3 months. By using combination therapy when needed, splenectomy can be avoided in the vast majority of cases. When it is necessary, it should be delayed, if at all possible, for at least a year after diagnosis.

• Question 440:

  A 4-year-old girl is brought in to the office by her mother. She developed chicken pox about 6 days ago. She appeared to be recovering well but mother became concerned because she was persistently scratching at several of the lesions and they were not healing. On examination, the child is afebrile and generally well appearing. On examination of her skin you see the following image What would be the most appropriate treatment?

  

  A. topical triamcinolone 0.1% cream

  B. topical nystatin cream

  C. oral acyclovir

  D. oral cephalexin

  E. no treatment is necessary as this is a self-limited condition

  Correct Answer: D Section: (none)

  Explanation:

  The image provided shows a classic case of impetigo. This is a common skin infection of childhood. It frequently occurs following a case of chickenpox and is due to the child picking or scratching at the varicella lesions, resulting in a secondary bacterial infection. GAS infection is the most common cause of impetigo associated with varicella infections. It is markedly more prevalent than the next most common infectious agent, S. aureus. Tinea corporis, often due to T. rubrum, is also known as ringworm. It classically is a circular lesion with a red, raised border, and central clearing. Contact dermatitis, from exposure to an irritant such as poison ivy, often causes plaques of erythema and edema with superimposed vesicles. This is also frequently secondarily infected with GAS from scratching. Warts, caused by the human papilloma virus, do not typically appear as the lesions in the image. Of the options listed, oral cephalexin would be the most appropriate initial therapy. Most GAS isolates are sensitive to first-generation cephalosporins, such as cephalexin. Topical steroids are useful for inflammatory or allergic conditions, topical nystatin for a fungal infection (such as tinea corporis) and oral acyclovir can be used early in the course of a varicella infection