10 Diseases of Infancy and Childhood
1 A 20-year-old woman gives birth at term to an infant weighing 1900 g. On physical examination, the infant’s head size is normal, but the crown-heel length and foot length are reduced. There are no external malformations. Throughout infancy, developmental milestones are delayed. Which of the following conditions occurring during gestation would most likely produce these findings?
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(E) 2 An 18-month-old African-American boy is found dead in his crib one morning. The distraught parents, both factory workers, are interviewed by the medical examiner and indicate that the child was not ill. The medical examiner finds no gross or microscopic abnormalities at autopsy, and the results of all toxicologic tests are negative. The medical examiner tells the parents that although she cannot yet determine the cause of death, she believes that sudden infant death syndrome (SIDS) is very unlikely. This conclusion by the medical examiner is most likely based on which of the following factors?
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(E) 3 A 17-year-old primigravida has an uneventful pregnancy until 25 weeks, when she notes absence of fetal movement for a day. On examination, her temperature is 37°C, pulse is 80/min, and blood pressure is 115/80 mm Hg. No fetal heart tones are present. An ultrasound examination shows no apparent fetal anomalies. The next day she develops premature rupture of fetal membranes, and the next day a stillborn fetus is delivered. Examination of the placenta shows normal size for gestational age, but microscopically neutrophils infiltrate the chorion and amnion. What is the most likely diagnosis?
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(F) 4 A 12-year-old child has had increasing episodes of diarrhea for the past 3 years. The child’s stools are bulky and foul-smelling. The child also has a history of multiple respiratory tract infections. On physical examination, vital signs include temperature of 38.1°C, pulse of 80/min, respirations of 20/min, and blood pressure of 90/55 mm Hg. On auscultation, diffuse crackles are heard over both lungs. Laboratory findings include quantitative stool fat of greater than 10 g/day. Sputum cultures have grown Pseudomonas aeruginosa and Burkholderia cepacia. Which of the following is most likely to explain the findings in this child?
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5 The mother of a 6-month-old boy notices that he has a palpable abdominal mass. On physical examination, the infant has a temperature of 37.8°C, and he is at the 33rd percentile for weight. An abdominal CT scan shows a solid 5.5-cm mass involving the right adrenal gland. Laboratory studies show that 24-hour urine levels of homovanillic acid (HVA) and vanillylmandelic acid (VMA) are increased. The adrenal gland is excised surgically; the histologic appearance of the mass is shown in the figure. Which of the following features of this lesion is associated with a poor prognosis?
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6 A 28-year-old woman, G1, P0, has an uncomplicated pregnancy until 28 weeks’ gestation, when she develops uterine contractions and has premature rupture of membranes. An ultrasound reveals a lesion with the representative gross appearance shown in the figure. Which of the following is the most likely diagnosis of this lesion?
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7 A 25-year-old woman gives birth at 28 weeks’ gestation. The newborn girl has initial Apgar scores of 5 and 6 at 1 and 5 minutes, but within 1 hour, she experiences severe respiratory distress and appears cyanotic. A chest radiograph shows a bilateral ground-glass appearance in the lungs. She is treated with assisted ventilation and nutritional support and seems to improve for 24 hours, but then becomes progressively more cyanotic, develops seizures, and dies 4 days after birth. At autopsy, the newborn’s lungs have the microscopic appearance shown in the figure. Which of the following conditions best accounts for these findings?
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(E) 8 A term infant has initial Apgar scores of 8 and 10 at 1 and 5 minutes. On auscultation of the chest, a heart murmur is audible. The infant is at the 30th percentile for height and weight. Echocardiography shows a membranous ventricular septal defect. Which of the following events is most likely to have resulted in the appearance of the ventricular septal defect?
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(F) 9 In a study of lung maturation, the amount of surfactant at different gestational ages is measured. Investigators find that the amount of surfactant in the developing lung increases between 26 and 32 weeks’ gestation, with progression of lung architecture to a saccular alveolar configuration. This increase in surfactant is most likely related to which of the following developmental events?
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(E) 10 A 22-year-old primigravida gives birth to a boy at 38 weeks’ gestation. On physical examination, the infant appears normal except for a single midline cleft of the upper lip. The cleft lip interferes with breastfeeding, but the infant gains weight normally. The mother asks if there is any risk that future children will be born with a similar malformation. What is the most appropriate information to give her?
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(E) 11 A 20-year-old woman known to have an inborn error of metabolism is planning for her first pregnancy. She is advised by her physician to begin a phenylalanine-free diet before conception and to continue this diet throughout all three trimesters of her pregnancy. This special diet is most likely to aid in preventing which of the following problems in her infant?
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(E) 12 A 38-year-old primigravida has premature rupture of membranes at 38 weeks’ gestation, necessitating delivery. At birth, the infant is noted to have a two-vessel umbilical cord, a cleft lip, a heart murmur, and spina bifida. Which of the following factors is most likely to increase the risk of hyaline membrane disease in the infant?
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(E) 13 A term infant develops vomiting and diarrhea a few days after birth. By the end of the first week of life, the infant is icteric. Cataracts develop 1 month later. At 1 year of age, developmental milestones are not being met. At age 2, the infant dies of Escherichia coli septicemia. A deficiency of which of the following substances was most likely present in this child?
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(G) 14 A neonate is born at 36 weeks’ gestation. On physical examination, the neonate manifests severe hydrops fetalis, hepatosplenomegaly, generalized icterus, and scattered ecchymoses of the skin. Laboratory studies show a hemoglobin concentration of 9.4 g/dL and platelet count of 67,000/mm3. Ultrasound of the head shows ventricular enlargement. Death occurs 14 days after birth. At autopsy, there is extensive subependymal necrosis, with microscopic evidence of encephalitis. Within the areas of necrosis, there are large cells containing intranuclear inclusions. Which of the following organisms is most likely to produce these findings?
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(F) 15 An infant is born prematurely at 32 weeks’ gestation to a 34-year-old woman with gestational diabetes. At birth, the infant is at the 50th percentile for height and weight. On physical examination, there are no congenital anomalies. The infant requires 3 weeks of intubation with positive-pressure ventilation and dies of sepsis at 4 months of age. At autopsy, the lungs show bronchial squamous metaplasia with peribronchial fibrosis, interstitial fibrosis, and dilation of airspaces. Which of the following conditions best explains these findings?
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(E) 16 An 18-year-old woman gives birth to a term infant after an uncomplicated pregnancy and delivery. Over the first few days of life, the infant becomes mildly icteric. On physical examination, there are no morphologic abnormalities. Laboratory studies show a neonatal bilirubin concentration of 4.9 mg/dL. The direct Coombs test of the infant’s RBCs yields a positive result. The infant’s blood type is A negative, and the mother’s blood type is O positive. Based on these findings, which of the following events is most likely to occur?
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(E) 17 A 3-year-old child is brought to the physician for a routine health maintenance examination. The physician examining the child notes a large port wine stain on the left side of the child’s face. This irregular, slightly raised, red-blue area is not painful, but is very disfiguring. Histologically, this lesion is most likely composed of a proliferation of which of the following tissue components?
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(E) 18 In a study of inheritance of the cystic fibrosis gene (CFTR), the genetic mutations in carriers and affected individuals are documented. Based on these findings, investigators determine that there is no simple screening test to detect all carriers of mutations of the CFTR gene. Which of the following is most likely to be the greatest limitation to development of a screening test for CFTR mutations?
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(E) 19 A 3-year-old boy is noted to have absence of the iris bilaterally, cryptorchidism, hypospadias, and mental retardation. His mother has noticed over the past 3 months that the child has an enlarging abdomen. On physical examination, there is a palpable mass. An abdominal CT scan shows bilateral adrenal enlargement and pancreatic enlargement. There is a 6-cm solid mass in the left kidney. Which of the following congenital disorders is the most likely diagnosis?
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(G) 20 A newborn boy delivered at 38 weeks is small for gestational age. Physical examination shows microcephaly, frontal bossing, long and narrow forehead, hypotelorism, maxillary and mandibular hypoplasia, narrow palpebral fissures, thin elongated philtrum, vermilion border of the upper lip, dental malocclusion, saddle nose, tooth enamel hypoplasia, and uvular hypoplasia. Ocular problems include microphthalmia, corneal clouding, coloboma, nystagmus, strabismus, and ptosis. A systolic murmur is heard on auscultation, and echocardiography shows a membranous ventricular septal defect. Which of the following conditions is most likely to produce these findings?
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(E) 21 A 20-year-old woman, G3, P2, has a screening ultrasound at 18 weeks’ gestation that shows hydrops fetalis but no malformations. The woman’s two previous pregnancies ended at term in live births. The current pregnancy results in a live birth at 36 weeks. Physical examination shows marked hydrops of the infant and placenta. Laboratory studies show a cord blood hemoglobin level of 9.2 g/dL and total bilirubin concentration of 20.2 mg/dL. Which of the following laboratory findings best explains the pathogenesis of this infant’s disease?
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(E) 22 A 3-month-old, previously healthy boy was found dead by his mother late one evening. When she put him in his crib 1 hour earlier, he showed no signs of distress. The infant’s term birth had followed an uncomplicated pregnancy, and he had been feeding well and gaining weight normally. Which of the following is the medical examiner most likely to find at autopsy?
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(E) 23 A 25-year-old woman, G3, P2, is in her 39th week of pregnancy. She has felt no fetal movement for 1 day. The infant is stillborn on vaginal delivery the next day. On physical examination, there are no external anomalies. Microscopic examination of the placenta shows acute chorioamnionitis. Which of the following infectious agents was most likely responsible for these events?
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(E) 24 A 19-year-old woman, G2, P1, has a screening ultrasound at 20 weeks’ gestation that shows no abnormalities. Premature labor leads to an emergent vaginal delivery at 31 weeks, however. Soon after birth, the neonate develops respiratory distress requiring intubation with positive-pressure ventilation. Which of the following prenatal diagnostic tests could have best predicted this neonate’s respiratory distress?
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