USMLE USMLE Certifications USMLE-STEP-3 Questions & Answers

• Question 41:

  A2-week-old infant is brought to the office for a check-up. The father relates that they have no concerns except that the baby seems to have tearing from his left eye. They also point out some swelling at the edge of his left eye. The infant is eating, sleeping, stooling, and voiding well. On examination, you find a 1/2 × 1/2 cm firm nodule inferior to the medial canthus of the left eye. What does this most likely represent?

  A. dermoid cyst

  B. nasolacrimal duct obstruction

  C. mucocele

  D. accessory lacrimal gland

  E. frontal encephalocele

  Correct Answer: B Section: (none)

  Explanation:

  Relative immaturity of the lacrimal drainage system can result in the accumulation of debris in the nasolacrimal duct. This will manifest as a swelling inferior to the middle canthus. Dermoid cysts in children are commonly found as a subcutaneous nodule on the lateral portion of the eyebrow. Mucoceles are usually found as fleshy papules on the inner portion of the lower lip. Frontal encephaloceles are midline in location.

• Question 42:

  A 4-year-old child is seen in the emergency department after having a seizure at home. This is the first time that this has happened. The mother says that the child was sitting on the couch watching television when she suddenly became limp, started drooling, and having generalized tonic-clonic movements of her arms and legs. The mother relates that the child felt like she was "burning up" and that the tonic-clonic activity stopped after a few minutes. The mother says that the child is otherwise healthy, does not take any medicines, and has never been hospitalized. The child's immunizations are up-todate, and she has no known drug allergies. On examination, the vital signs are temperature of 104°F, BP 97/49, HR 112, and RR

  26. The child is sitting on the examination table playing with stickers and drawing. She has a mild amount of clear nasal congestion but her examination is otherwise normal. When asked, the child replies that she feels fine.

  Which of the following medications would be most appropriate to be given to the child while in the emergency department?

  A. acetaminophen (Tylenol) for fever as needed

  B. phenytoin (Dilantin)

  C. phenobarbital

  D. diazepam (Valium)

  E. ceftriaxone (Rocephin)

  Correct Answer: A Section: (none)

  Explanation:

  Febrile seizures are the most common cause of seizures in childhood. These are classically seen early in an illness and when there is a rapid rise in the child's temperature. These seizures usually last less than 23 minutes (typical febrile seizures last no longer than 15 minutes) and have a very mild, short, postictal phase. Children who have seizures that are the result of bacterial meningitis will not subsequently be normal. For typical febrile seizures, in an otherwise healthy and well-appearing child, no evaluation (outside of treating any underlying cause of the fever) is warranted. Blood and urine cultures would not be necessary in evaluation of the seizures, but they may be warranted in evaluation of the fever. An EEG and head CT will nearly universally be normal and are unwarranted. A single typical febrile seizure routinely does not require any anticonvulsant therapy. If the child has had multiple febrile seizures, or the seizures are not typical, anticonvulsant therapy may be entertained. Prophylactic anticonvulsant therapy is usually initiated after the third febrile seizure. Occasionally, children may have convulsions associated with fevers which do not fall into the typical features. Some criteria which would make a febrile seizure atypical would be prolonged duration (greater than 15 minutes) and a prolonged postictal state

• Question 43:

  A 4-year-old child is seen in the emergency department after having a seizure at home. This is the first time that this has happened. The mother says that the child was sitting on the couch watching television when she suddenly became limp, started drooling, and having generalized tonic-clonic movements of her arms and legs. The mother relates that the child felt like she was "burning up" and that the tonic-clonic activity stopped after a few minutes. The mother says that the child is otherwise healthy, does not take any medicines, and has never been hospitalized. The child's immunizations are up-todate, and she has no known drug allergies. On examination, the vital signs are temperature of 104°F, BP 97/49, HR 112, and RR

  26. The child is sitting on the examination table playing with stickers and drawing. She has a mild amount of clear nasal congestion but her examination is otherwise normal. When asked, the child replies that she feels fine.

  Which test(s) should be performed while the child is in the emergency department to evaluate the cause of these seizures?

  A. electroencephalogram (EEG)

  B. no testing is needed

  C. noncontrast head CT

  D. lumbar puncture

  E. blood and urine cultures

  Correct Answer: B Section: (none)

  Explanation:

  Febrile seizures are the most common cause of seizures in childhood. These are classically seen early in an illness and when there is a rapid rise in the child's temperature. These seizures usually last less than 23 minutes (typical febrile seizures last no longer than 15 minutes) and have a very mild, short, postictal phase. Children who have seizures that are the result of bacterial meningitis will not subsequently be normal. For typical febrile seizures, in an otherwise healthy and well-appearing child, no evaluation (outside of treating any underlying cause of the fever) is warranted. Blood and urine cultures would not be necessary in evaluation of the seizures, but they may be warranted in evaluation of the fever. An EEG and head CT will nearly universally be normal and are unwarranted. A single typical febrile seizure routinely does not require any anticonvulsant therapy. If the child has had multiple febrile seizures, or the seizures are not typical, anticonvulsant therapy may be entertained. Prophylactic anticonvulsant therapy is usually initiated after the third febrile seizure. Occasionally, children may have convulsions associated with fevers which do not fall into the typical features. Some criteria which would make a febrile seizure atypical would be prolonged duration (greater than 15 minutes) and a prolonged postictal state

• Question 44:

  A 4-year-old child is seen in the emergency department after having a seizure at home. This is the first time that this has happened. The mother says that the child was sitting on the couch watching television when she suddenly became limp, started drooling, and having generalized tonic-clonic movements of her arms and legs. The mother relates that the child felt like she was "burning up" and that the tonic-clonic activity stopped after a few minutes. The mother says that the child is otherwise healthy, does not take any medicines, and has never been hospitalized. The child's immunizations are up-todate, and she has no known drug allergies. On examination, the vital signs are temperature of 104°F, BP 97/49, HR 112, and RR

  26. The child is sitting on the examination table playing with stickers and drawing. She has a mild amount of clear nasal congestion but her examination is otherwise normal. When asked, the child replies that she feels fine.

  What is the most likely diagnosis?

  A. bacterial meningitis

  B. first seizure in an epilepsy syndrome

  C. viral encephalitis

  D. typical febrile seizure

  E. hypocalcemic tetany

  Correct Answer: D Section: (none)

  Explanation:

  Febrile seizures are the most common cause of seizures in childhood. These are classically seen early in an illness and when there is a rapid rise in the child's temperature. These seizures usually last less than 23 minutes (typical febrile seizures last no longer than 15 minutes) and have a very mild, short, postictal phase. Children who have seizures that are the result of bacterial meningitis will not subsequently be normal. For typical febrile seizures, in an otherwise healthy and well-appearing child, no evaluation (outside of treating any underlying cause of the fever) is warranted. Blood and urine cultures would not be necessary in evaluation of the seizures, but they may be warranted in evaluation of the fever. An EEG and head CT will nearly universally be normal and are unwarranted. A single typical febrile seizure routinely does not require any anticonvulsant therapy. If the child has had multiple febrile seizures, or the seizures are not typical, anticonvulsant therapy may be entertained. Prophylactic anticonvulsant therapy is usually initiated after the third febrile seizure. Occasionally, children may have convulsions associated with fevers which do not fall into the typical features. Some criteria which would make a febrile seizure atypical would be prolonged duration (greater than 15 minutes) and a prolonged postictal state

• Question 45:

  A 6-month-old male infant presents to your clinic because the mother is concerned that he is not eating well and he has been constipated. The mother tells you that her prenatal course and delivery were uneventful. On physical examination, the infant has a puffy face, large tongue, and persistent nasal drainage The above condition can be caused by a deficiency of which of the following?

  A. iron

  B. vitamin C

  C. vitamin D

  D. iodine

  E. cortisol

  Correct Answer: D Section: (none)

  Explanation:

  Hypothyroidism results from inadequate thyroid hormone production or a defect in thyroid hormone receptor activity. Hypothyroidism can be congenital or acquired. Most infants with congenital hypothyroidism are asymptomatic at birth. Feeding difficulties, choking spells, and somnolence often present during the first month of life. Respiratory distress can also occur in part due to the large tongue and nasal obstruction. On physical examination, you may find a large abdomen, umbilical hernias, subnormal temperature, cold skin, murmurs, or bradycardia. Iodine is absorbed in the GI tract as iodide. Iodide is concentrated in the thyroid gland and four atoms are incorporated into each molecule of thyroxine. Profound dietary deficiency of iodine will result in hypothyroidism and is the most common cause of goiter in the world. Rickets results from a deficiency of vitamin D.

  This condition predominately affects the long bones and skull. Vitamin C deficiency results in scurvy, a condition with impaired collagen formation. The clinical manifestations may include changes in the gums, loosening of teeth, brittle bones, and swollen joints. Pallor is the most important sign of iron-deficiency anemia. Children may also have the desire to ingest unusual substances such as ice or dirt. Finally, hyponatremia and hypoglycemia are the prominent presenting signs of adrenal insufficiency in infants

• Question 46:

  Which of the following is regulated by the parathyroid gland?

  A. calcium

  B. zinc

  C. iodine

  D. iron

  E. vitamin B12

  Correct Answer: A Section: (none)

  Explanation:

  Parathormone (PTH), with vitamin D, is a major regulator of the serum levels of calcium. PTH is made in the chief cells of the four parathyroid glands and exerts effects mainly on the bone and kidneys to maintain adequate serum levels of calcium.

• Question 47:

  A 6-month-old male infant presents to your clinic because the mother is concerned that he is not eating well and he has been constipated. The mother tells you that her prenatal course and delivery were uneventful. On physical examination, the infant has a puffy face, large tongue, and persistent nasal drainage.

  Which of the following conditions is most likely to present with these findings?

  A. rickets

  B. scurvy

  C. hypothyroidism

  D. microcytic anemia

  E. adrenocortical insufficiency

  Correct Answer: C Section: (none)

  Explanation:

  Hypothyroidism results from inadequate thyroid hormone production or a defect in thyroid hormone receptor activity. Hypothyroidism can be congenital or acquired. Most infants with congenital hypothyroidism are asymptomatic at birth. Feeding difficulties, choking spells, and somnolence often present during the first month of life. Respiratory distress can also occur in part due to the large tongue and nasal obstruction. On physical examination, you may find a large abdomen, umbilical hernias, subnormal temperature, cold skin, murmurs, or bradycardia. Iodine is absorbed in the GI tract as iodide. Iodide is concentrated in the thyroid gland and four atoms are incorporated into each molecule of thyroxine. Profound dietary deficiency of iodine will result in hypothyroidism and is the most common cause of goiter in the world. Rickets results from a deficiency of vitamin D.

  This condition predominately affects the long bones and skull. Vitamin C deficiency results in scurvy, a condition with impaired collagen formation. The clinical manifestations may include changes in the gums, loosening of teeth, brittle bones, and swollen joints. Pallor is the most important sign of iron-deficiency anemia. Children may also have the desire to ingest unusual substances such as ice or dirt. Finally, hyponatremia and hypoglycemia are the prominent presenting signs of adrenal insufficiency in infants

• Question 48:

  A 9-month-old male infant is brought to your office for evaluation of new skin lesions. The mother tells you that she recently had to return to work, and the child is now in day care. He has since developed new erythematous facial plaques. She also reports that the child has been irritable with chronic diarrhea. On examination, the child has dry scaly plaques symmetrically distributed in the perianal and perioral areas. Which deficiency does this child likely have?

  

  A. calcium

  B. zinc

  C. iodine

  D. iron

  E. vitamin C

  Correct Answer: B Section: (none)

  Explanation:

  The absence, or malabsorption, of zinc from the diet will result in zinc deficiency. The clinical entity is called acrodermatitis enteropathica. Symptoms may manifest during the transition from breast milk to cow's milk. The typical dermatologic manifestations of this are symmetrically distributed perianal and perioral (in a horseshoe pattern) dermatitis. The skin lesions are eczematous, dry, scaly, or psoriasiform. Children with vitamin C deficiency present with petechial hemorrhages of the skin and mucus membranes. Hypocalcemia does not include specific dermatologic changes. Tetany is a classic manifestation of hypocalcemia. Skin pallor is the most important sign of iron deficiency. Children with inadequate iodine in their diet may develop hypothyroidism.

• Question 49:

  Deficiency of which of the following is the most common nutritional cause of anemia?

  A. calcium

  B. vitamin B12 deficiency

  C. iodine

  D. iron

  E. vitamin C

  Correct Answer: D Section: (none)

  Explanation:

  Iron deficiency is a common finding. Most proprietary infant formulas have iron supplementation. Infants who are strictly breast fed may require oral iron supplementation. A total body iron deficiency can result in a microcytic, hypochromic anemia. Testing of total serum iron, ferritin, and total iron binding capacity can help clarify the body iron stores.

• Question 50:

  A33-year-old female complains of a sore throat and general malaise over the past week after being treated for an upper respiratory infection. On examination, her thyroid gland is nodular and tender to palpation. Which of the following is the best treatment?

  A. penicillin G

  B. salicylates

  C. fluconazole (Diflucan)

  D. subtotal thyroidectomy

  E. total thyroidectomy

  Correct Answer: B Section: (none)

  Explanation: Subacute thyroiditis (giant cell, granulomatous, or de Quervain's thyroiditis) is an acute inflammatory disease of the thyroid gland. The cause is thought to be viral and it is often preceded by an upper respiratory tract infection. Patients may also experience a viral prodrome marked by muscle aches, fever, and general malaise. The thyroiditis is characterized by constant and often severe pain over the gland that is aggravated with swallowing. It often presents as a sore throat. Physical examination reveals a firm, nodular, and tender thyroid gland with overlying erythema and warmth. Patients may have symptoms of hyperthyroidism due to the release of thyroid hormone from the gland, secondary to the inflammation. The disorder is usually self-limited and treatment focuses on conservative measures for pain control. Salicylates and nonsteroidal anti-inflammatory agents are successfully used in mild to moderate cases. For severe pain and swelling, oral glucocorticoids such as prednisone may be required. If symptoms of hyperthyroidism are present, beta-adrenergic blockage may also be needed. Antithyroidal medications are ineffective because the hyperthyroidism is not caused by increased thyroid hormone synthesis