Pediatric ‘A’ Unit 2020-January Session MCQs EXPLANATION

Pediatric ‘A’ Unit 

2020-January  Session MCQs

EXPLANATION

MCQ#01

A 3-year-old boy is brought to the office by his mother for the evaluation of recurrent bone fractures. His first fracture was that of the femur, and occurred when he was 6 months old. He had a fracture of the wrist 4 months ago. His mother also has a history of multiple fractures since childhood. She lost all her teeth at a very early age and is complaining of deafness. On examination, both mother and son have blue sclerae.

What is the most likely involved disease process?

A. Mutations in type 1 collagen

B. Mutations in fibrillin 1 gene

C. Child abuse

D. Vitamin-D deficiency

E. Congenital syphilis

MCQ#01

Explanation:

A.     The above child is most likely suffering from osteogenesis imperfecta, which is an inherited connective tissue disorder caused by a mutation in the genes coding for type I collagen. Since type I collagen is an important structural protein that is present in the skin, sclera, bone, tendon and ligament, patients with this disorder present with multiple recurrent fractures, blue sclera, hearing loss, joint laxity, short stature, and scoliosis.

B.      Marfan syndrome is one of the most common connective tissue disorders, and is caused by mutation of the fibrillin-1 gene. Its mode of inheritance is autosomal dominant. The common features of this disorder include skeletal manifestations (e.g. arachnodactyly, hypermobility of joints), ectopia lentis, and aortic root dilatation.

C.      Child abuse suspected in the presence of any of the following: retinal hemorrhages, burns, bruising, fractures or abrasions. This is a good differential diagnosis for the given case; however, the features of this patient (e.g., fractures, blue sclerae, family history of fractures and hearing loss) are very typical of osteogenesis imperfecta.

D.     Children with rickets have slow growth and skeletal deformities. Blue sclerae and hearing loss are not the features of rickets.

E.      Early manifestations of congenital syphilis include jaundice, rash, lymphadenopathy, rhinitis and hepatosplenomegaly. Late manifestations occur around two year of age; these include saber shins, keratitis, Hutchinson's teeth, saddle-nose deformity and deafness. The above child has typical features of osteogenesis imperfecta, not congenital syphilis.

Educational Objective:

Osteogenesis imperfecta is caused by mutations in type 1 collagen. Its typical features are blue sclera and recurrent fractures.

MCQ#02

A 13-year-old boy comes to you because of hematuria and lower abdominal pain. This is his third episode of hematuria in the past 2 years. He has a family history of renal disease. His temperature is 37.1° C (98.9°F); blood pressure is 140/90 mm Hg, pulse is 80/min, and respirations are 14/min. Examination shows mild sensorineural deafness bilaterally. Urinalysis shows hematuria and proteinuria. Laboratory studies show blood urea of 50 mg/dl and serum creatinine of 3.1 mg/dl; serum complement levels are normal. Renal biopsy shows foam cells, and immunofluorescence shows no immunoglobulins or complement. Electron microscopy shows alternating areas of thinned and thickened capillary loops with splitting of GBM.

Which of the following is the most likely diagnosis?

A.     Alport's syndrome

B.      Acute interstitial nephritis

C.      Idiopathic anti-GBM antibody mediated glomerulonephritis

D.     Mixed essential cryoglobulinemia

E.      Wegener's granulomatosis

Explanation:

A.     The above clinical and laboratory picture is the classic presentation of Alpert's syndrome. This is a familial disorder which usually presents in childhood as recurrent gross hematuria and proteinuria. Sensorineural deafness usually occurs. Electron microscopy findings include alternating areas of thinned and thickened capillary loops with splitting of the glomerular basement membrane (GBM).

C.      Thin basement membrane disease is also a familial disorder, but it presents in adulthood as microscopic hematuria without proteinuria. Renal biopsy reveals a markedly thinned basement membrane.

Educational Objective:

Suspect Alpert's syndrome in patients with recurrent episodes of hematuria, sensorineural deafness and a family history of renal failure.

MCQ#03

While working in the newborn nursery, you have the chance to counsel a first time mother. She had a healthy pregnancy and good prenatal care. The infant was delivered via normal spontaneous vaginal delivery and is doing well. You are counseling the mother on the benefits of breast-feeding, and she asks you what the differences are between human milk and formula.

Which of the following is a true statement?

A.     Human milk has more calcium and phosphorus than formula

B.      Human milk provides adequate amounts of vitamin D

C.      Human milk contains only trace amounts of immunoglobulin A

D.     Human milk protein absorbs better and improves gastric emptying

E.      The main advantage of formula is, it decreases colic

Explanation:

Human milk is considered to be the Ideal nutritional source for full-term infants. The American Academy of Pediatrics recommends exclusive breastfeeding until 6 months of age and then continuation of breastfeeding along with the introduction of solid foods until the infant is 1 year old. Infant formulas have improved greatly over time to more closely resemble human milk, but differences still exist.

The composition of human milk varies based on the mother's diet, the duration of lactation, and the needs of the Infant. The protein in human milk is 70% whey and 30% casein, and the protein content Is highest at birth and decreases over the first month of life. Whey is more easily digested than casein and helps to improve gastric emptying. Human milk also contains lactoferrln, lysozyme, and secretory immunoglobulin A proteins that confer Improved Immunity to the Infant. The main carbohydrate in both human milk and standard Infant formulas Is lactose. Although calcium and phosphorus content Is significantly lower In human milk when compared to formula, these minerals are better absorbed from human milk. Breast milk has an inadequate supply of vitamin D and exclusively breast-fed Infants must receive supplemented vitamin D.

(Choice A) Although human milk contains less calcium and phosphorus than formula, these minerals are better absorbed from human milk. Therefore, no clinical difference in bone health is seen between breast-fed and formula-fed infants.

(Choice B) The amount of vitamin D In breast milk is not adequate and exclusively breast-fed Infants must receive vitamin D supplementation.

(Choice C) Human milk contains proteins such as lactoferrin, lysozyme, and secretory immunoglobulin A, all of which help with immunity. In contrast, there is only a trace amount of these proteins in infant formulas.

(Choice E) Human milk is associated with less reflux and colic than formula.

Educational objective:

Human milk is the Ideal form of nutrition for term infants. The major protein source is whey, which is more easily digested than casein and helps to improve gastric emptying.

MCQ#04

A 12 year-old-girl with hereditary spherocytosis is scheduled for a splenectomy. She was previously managed with folate therapy and occasional blood transfusions, but her anemia became refractory to medical management alone. Before the operation, she is told that she will have an enhanced risk of developing pneumococcal sepsis. She then asks, "How long will this risk last?"

What is the best response to her question?

A.     2 weeks

B.      Up to 6 months

C.      Up to 2 years

D.     Up to 10 years

E.      More than 10 years

Explanation:

Hereditary spherocytosis is an autosomal dominant disorder. It is characterized by a lack of spectrin in the red cell membrane, which causes the cells to become spheres, instead of being normal, flexible and durable biconcave discs. The poorly flexible spherical cells are thus unable to pass through the small fenestrations in the splenic red pulp, and hemolysis takes place when the red cells are trapped within the spleen.

The treatment for most patients involves supportive care with oral folic acid and blood transfusions during periods of extreme anemia. Splenectomy is considered if patients have moderate to severe spherocytosis, or are refractory to medical management. The benefits of splenectomy must be balanced against the immediate and long-term risks of the procedure. Life-threatening anemia and the need for regular transfusions may be abolished by splenectomy, although a mild degree of anemia usually persists. Immediate risks (e.g. , hemorrhage, postoperative infection, injury to nearby organs) are infrequent.

The most feared long-term complication is overwhelming sepsis with encapsulated bacteria, most commonly Streptococcus pneumoniae.

Studies have shown that the risk for pneumococcal sepsis is present up to 30 years and probably longer after splenectomy. To decrease this risk, current recommendations call for the administration of anti-pneumococcal, Haemophilus, and meningococcal vaccines several weeks before the operation, and daily oral penicillin prophylaxis for three to five years following splenectomy or until adulthood (for pediatric patients). In view of reported deaths from sepsis up to 30 years or more after splenectomy, a case can be made for lifetime penicillin prophylaxis. Alternatively, antibiotics can be made available at home for immediate treatment of any significant fever.

Educational Objective:

Studies have shown that the risk for sepsis is present up to 30 years and probably longer after splenectomy. Current recommendations state that patients should receive anti-pneumococcal, Haemophilus, and meningococcal vaccines several weeks before the operation, and daily oral penicillin prophylaxis for three to five years following splenectomy.

 MCQ#05

A 2-year-old girl is brought to the office for a rash. She was in good health until 3 days ago when she developed fever, cough, rhinorrhea, and "pink eyes." Yesterday, the patient developed a rash on her face that has now spread over her entire body. The girl lives with her parents and several pets, including a dog, turtle, and new kitten. Approximately 6 weeks ago, the family returned from a trip to the Bannu to visit her grandparents. She takes no medications and has no allergies. Temperature is 39.6^oC (103.3^oF) and other vital signs are normal. Examination shows a blanching, erythematous maculopapular rash covering her face and entire body except for the palms and soles.

Which of the following will most likely prevent the spread of this patient's infection to other patients in the office?

A.     Airborne precautions

B.      Antibiotic prophylaxis

C.      Contact precautions

D.     Droplet precautions

E.      Hand hygiene

This patient has the classic cough, coryza, and conjunctivitis prodrome with subsequent exanthem of measles (rubeola). Measles is a highly contagious virus that can cause outbreaks in unvaccinated persons. Symptoms manifest 1-3 weeks after inhalation of infectious respiratory particles, which are capable of remaining airborne for hours in a closed space (eg, airplane, clinic waiting room). Patients are most contagious during the prodrome but can spread disease for several days even after the resolution of the rash. Patients with known or suspected measles should be isolated and placed on airborne precautions.

The best way to prevent measles infection is by 2 doses of the live attenuated measles vaccine, which generates immunity in >95% of vaccinated persons. Measles occurs worldwide, particularly in areas with low vaccine rates. Because this patient returned from international travel S weeks ago and the incubation period is 1-3 weeks, she likely acquired measles domestically as it is becoming increasingly common due to hesitancy and refusal regarding vaccination.

(Choice B) Antibiotic prophylaxis can decrease transmission of Neisseria meningitides or Bordete/la pertussis but has no effect on measles transmission.

(Choice C) Contact precautions (ie, gown, gloves) can prevent transmission of organisms that spread by contact (eg, methicillin-resistant Staphylococcus aureus, rotavirus) but do not prevent airborne transmission.

(Choice D) Droplet precautions (ie, surgical mask) can prevent transmission of organisms that spread via droplets (eg, influenza, respiratory syncytial virus), which are relatively large and have a short range. However, surgical masks do not block small airborne particles (eg, measles, varicella, tuberculosis).

(Choice E) Hand hygiene is an extremely effective method of preventing the spread of organisms by fecal-oral route (eg, enterovirus, Clostridium difficile), droplets, and secretions. However, hand hygiene cannot prevent the spread of airborne illnesses.

Educational objective:

Measles is characterized by a prodrome of cough, coryza, and conjunctivitis followed by a maculopapular rash that spreads in a cephalocaudal pattern. This highly contagious infection is transmitted by the airborne route.

 MCQ#06

A newborn boy is brought to the nursery for evaluation after delivery. The mother received no prenatal care but reports that the pregnancy was uncomplicated and she was healthy. The infant was born via spontaneous vaginal delivery and required no resuscitation. Apgar scores were 8 and 9 at 1 and 5 minutes, respectively. On examination, the infant is below the 3rd percentile for weight, 25th percentile for length, and 50th percentile for head circumference. Hepatosplenomegaly is present on examination. Over the next 48 hours, the infant develops jaundice, clear rhinorrhea, and a maculopapular rash on the feet and buttocks that later desquamates.

Which of the following congenital infections is most likely in this patient?

A.     Cytomegalovirus

B.      HIV

C.      Rubella

D.     Syphilis

E.      Toxoplasmosis

Clinical findings of congenital infections
ALL	Intrauterine growth restriction Hepatosplenomegaly Jaundice Blueberry muffin spots
Cytomegalovirus	Periventricular calcifications
Toxoplasmosis	Diffuse intracerebral calcifications Severe chorioretinitis
Syphilis	Rhinorrhea Abnormal long-bone. radiographs Desquamating or bullous rash
Rubella	Cataracts Heart defects (eg, PDA)

This infant has profuse rhinorrhea and a desquamating skin rash, which are suggestive of congenital syphilis. This infection is acquired via transplacental transmission of Treponema pallidum from the mother to the fetus. Most infants with congenital syphilis are initially asymptomatic. Those who do have clinical findings as newbo.rns usually have nonspecific signs of congenital infection, including jaundice and hepatosplenomegaly (due to fetal reticuloendothelial activation), blueberry muffin spots (due to extramedullary hematopoiesis), and growth restriction (due to fetal inflammation).

Features that are more specific for congenital syphilis include:

1. Copious clear, purulent, or serosanguineous rhinorrhea (snuffles)

2. A diffuse maculopapular rash that can involve the palms and soles and may desquamate or become bullous

3. Abnormal long-bone radiographs (eg, metaphyseallucencies) The diagnosis of maternal syphilis is determined by serologic testing, usually with a nontreponemal test (eg, VORL test or rapid plasma reagin [RPR)) in combination with a treponemal-specific test (eg, Treponema pallidum particle agglutination assay). Prenatal diagnosis and penicillin treatment can prevent the majority of congenital syphilis cases.

For infants who do develop congenital syphilis, penicillin therapy is curative and prevents the development of late manifestations (eg, frontal bossing, saddle nose, Hutchinson teeth). Therefore, no infant should be discharged from the nursery until the mother's serologic testing for syphilis has been completed.

(Choice A) Congenital cytomegalovirus is characterized by periventricular calcifications (and microcephaly, in severe cases).

(Choice B) Infants with congenital HIV infection are usually asymptomatic at birth.

(Choice C) Congenital rubella syndrome classically presents with the triad of sensorineural hearing loss, cataracts, and heart defects (eg, patent d4ctus arteriosus).

(Choice E) Major clinical findings of congenital toxoplasmosis include diffuse intracranial calcifications, hydrocephalus, and severe chorioretinitis. Skin lesions and rhinorrhea are not seen.

Educational objective:

Congenital syphilis presents with nonspecific signs of congenital infection ijaundice, hepatosplenomegaly, blueberry muffin spots, and growth restriction). More specific findings that are highly suggestive of congenital syphilis include snuffles (copious rhinorrhea) and a maculopapular rash that may desquamate or become bullous.

MCQ#07

A 14-year-old boy collapses suddenly while playing basketball with his friends. The boy played basketball every weekend without any symptoms and was in his usual state of health prior to this event. He has no known past medical history and takes no medications. Family history is significant for a maternal uncle who died at age 25 for unknown reasons. Cardiopulmonary resuscitation is unsuccessful and the patient is pronounced dead.

Post-mortem examination would most likely show which of the following?

A.     Abnormal brain mass

B.     Hypertrophic cardiomyopathy

C.      Mutation in the LQT1 gene

D.     Pulmonary embolus

E.      Ruptured aortic aneurysm

MCQ#08

 A 14-year-old boy with a history of ulcerative colitis presents to the physician complaining of diarrhea and a rash. He states that his appetite has been decreased recently, and also complains of nausea and abdominal pain in addition to watery diarrhea. He has an erythematous rash on his distal arms and legs. His mother reports that he has had poor concentration and has been irritable lately. Vital signs are stable. Examination reveals a beefy red tongue that appears swollen. Abdominal examination is normal. The rash resembles sunburn and is located on his distal arms and legs. It is symmetrical and tender to palpation. Neurological examination is normal.

This patient’ symptoms are most likely due to a deficiency of which of the following vitamins?

A.     Thiamine

B.      Riboflavin

C.      Niacin

D.     Pyridoxine

E.      Cyanocobalamin

Explanation:

Deficiency of niacin (vitamin B3) leads to pellagra, which is characterized by diarrhea, dermatitis, dementia, and If severe, death. Pellagra is common in third world countries where the main diet consists of cereal or com, but can also be seen in people with bowel disease that interferes with vitamin absorption. Patients with pellagra typically present with gastrointestinal complaints (nausea, abdominal pain, or epigastric discomfort) along with glossitis and watery diarrhea. The characteristic dermatitis seen in pellagra occurs in sun exposed areas and resembles a sunburn; it is also typically bilateral and symmetric. As the rash progresses, the skin becomes hyperpigmented and thickened. Mental status changes can range from poor concentration to irritability, aggressiveness, and dementia. Death can occur In severe niacin deficiency if untreated. Treatment of pellagra Is niacin replacement.

(Choice A) Deficiency of thiamine (vitamin B1) causes beriberi or Wernicke-Korsakoff syndrome. These conditions are characterized by neurologic and psychiatric symptoms, and are often seen In alcoholics or patients who have had weight loss surgery.

(Choice B) Deficiency of riboflavin (vitamin B2 ) can lead to cheilosis, glossitis, seborrheic dermatitis (often affecting the genital areas), pharyngitis, and edema and/or erythema of the mouth.

(Choice D) Pyridoxine (vitamin 8&) deficiency causes irritability, depression, dermatitis, and stomatitis. It can also cause an elevated serum homocysteine concentration, which is a known risk factor for venous thromboembolic disease and atherosclerosis.

(Choice E) Deficiency of cyanocobalamin {vitamin 8,2) causes macrocytic anemia and peripheral neuropathy.

Educational objective:

Niacin (vitamin 83) deficiency causes pellagra, which is characterized by diarrhea, dermatitis, dementia, and possibly death.

MCQ#09

A 3-year-old boy is brought to the clinic due to 3 days of fever and painful swelling in his right groin. His medical history includes 4 previous episodes of cutaneous abscesses and a lung abscess due to Staphylococcus aureus, all of which required drainage and prolonged antimicrobial therapy. The boy's maternal uncle died in childhood from recurrent infections. The patient's temperature is 38.5 C (1 01.3 F). Physical examination shows an enlarged, tender, and fluctuant lymph node in the right inguinal area. There are several areas of scarring over previous drainage sites. The remainder of the physical examination is normal. Laboratory results are as follows:

Complete blood count

Hematocrit                      40%

Platelets                            320,000/mm,

Leukocytes                      11,000/mm'

Neutrophils                    50%

Bands                                  10%

Lymphocytes                  35%

Gram stain of fluid aspirated from the affected lymph node reveals numerous organism-filled, segmented neutrophils. Cultures grow Aspergillus niger.

Which of the following tests would most likely confirm this patient's diagnosis?

A.     B cell concentrations

B.      CH50 assay

C.      Dihydrorhodamine test

D.     Fluorescence in situ hybridization

E.      Immunoglobulin levels

 This patient's pulmonary abscess and recurrent cutaneous abscesses with organism-filled neutrophils are consistent with chronic granulomatous disease (CGD). CGD is a primary immunodeficiency syndrome caused by a mutation that prevents phagocytic oxidative burst (formation of H,02) and therefore impairs intracellular killing by phagocytes. CGD is most commonly inherited in an X-linked recessive manner, as seen in this male patient with a male extended family member who had similar symptoms.

Patients with CGD experience recurrent infections starting early in life and are particularly susceptible to catalase-positive organisms (eg, Staphylococcus aureus,Aspergillus). The lungs (eg, pneumonia, empyema) and skin/soft tissue (eg, abscesses, lymphadenitis) are the most common sites of infection. Phagocytic cells filled with bacteria are a frequent finding on Gram stain. The diagnosis is initially made by testing neutrophil function via detection or absence of an oxidative burst (eg, dihydrorhodamine 123 or nitroblue tetrazolium test). Patients with CGD should receive lifelong antimicrobial prophylaxis, and interferon gamma can be used to boost intracellular killing in severe cases.

(Choices A and E) Low B cell concentrations and immunoglobulin levels are characteristic of X-linked (Bruton) agammaglobulinemia. Patients present with recurrent sinopulmonary and gastrointestinal infections. Aspergillus infections and bacteria-filled phagocytes are inconsistent with X-linked agammaglobulinemia.

(Choice B) CH50 assays are used to determine total complement concentration. Complement deficiencies present with recurrent infections from encapsulated bacteria, particularly Neisseria. Staphylococcus aureus and Aspergillus infections are inconsistent with complement deficiency.

(Choices D ) T cell concentrations are markedly low in severe combined immunodeficiency as well as in 22q11 .2 deletion (DiGeorge syndrome). DiGeorge syndrome, definitively diagnosed by fluorescence in situ hybridization, also presents with dysmorphic facies, developmental delays, and hypocalcemia (due to parathyroid hypoplasia).

Educational objective:

Chronic granulomatous disease is caused by impaired intracellular killing by phagocytes.

Pneumonia, cutaneous abscesses, and suppurative adenitis are common. Diagnosis is made by neutrophil function testing ( eg, dihydrorhodamine 123 or nitroblue tetrazolium testing).

 MCQ#10

A 4-month-old boy is brought to the office for a routine visit. His parents are concerned about his "noisy breathing" that worsens when he cries. The patient was seen for this issue in the emergency department twice within the past month. He was given several "breathing treatments," which did not improve symptoms. The infant is given 3 oz of a cow's milk-based formula every 3 hours and has small spit-ups after each feeding. He was born at 37 weeks via spontaneous vaginal delivery. He is at the 20th percentile for height and weight. Physical examination demonstrates both inspiratory and expiratory stridor, which improves with extension of the neck but not when the infant is held prone.

Which of the following is the most likely diagnosis for this patient?

A.     Asthma

B.      Croup

C.      Epiglottitis

D.     Laryngomalacia

E.      Vascular ring

Vascular rings, or slings, result from abnormal development of the aortic arch, causing tracheal, bronchial, and/or esophageal compression. They can be either complete (eg, circumferential around the trachea and/or esophagus), such as a double aortic arch, or incomplete (eg, pulmonary artery sling). Up to 50% of patients also have a cardiac anomaly (eg, ventricular septal defect, tetralogy of Fallot).

Vascular rings present in patients age <1, with respiratory (eg, stridor, wheezing, coughing) and/or esophageal (eg, dysphagia, vomiting, difficulty feeding) symptoms. The stridor is often biphasic, although it is more prominent during expiration, and improves with neck extension, which decreases tracheal compression.

(Choice A) Asthma, characterized by lower airway inflammation and bronchospasm, causes wheezing. Stridor, a symptom of upper airway obstruction, is not associated with asthma.

(Choices B and E) Croup, which responds to nebulized racemic epinephrine, is a viral infection that presents with fever, rhinorrhea, acute onset of inspiratory stridor, and a "barky" cough. Laryngomalacia is due to collapse of the supraglottic structures during inspiration and presents with chronic inspiratory stridor that improves with prone positioning. Because the stridor associated with vascular rings is due to a fixed intrathoracic obstruction, nebulized racemic epinephrine and prone positioning do not improve symptoms, as In this patient.

(Choice C) Epiglottitis is an acute, life-threatening cause of upper airway obstruction. Children have respiratory distress (eg, stridor) and difficulty handling oral secretions due to swelling of the epiglottis. This patient's chronic symptoms are not consistent with epiglottitis.

Educational objective:

Vascular rings can encircle the trachea and/or esophagus and present with respiratory (eg, biphasic stridor, wheezing, coughing) and esophageal (eg, dysphagia, vomiting, difficulty feeding) symptoms. Stridor typically improves with neck extension.