Módulo 3 Pediatría Flashcards

Question

The 1-year-old brother of a child with known abetalipoproteinemia is evaluated by a pediatrician for the disease. The 1-year-old has been exhibiting steatorrhea and ataxia. Which of the following would most strongly support the suspected diagnosis? (A) Acanthocytes on peripheral smear (B) “Crumpled silk” histiocytes on bone marrow biopsy (C) Globoid cells on brain biopsy (D) Metachromatic deposits on sural nerve biopsy (E) "Sea-blue” histiocytes on bone marrow biopsy

Answer 1

Respuesta: A The correct **answer is A**. Numerous acanthocytes (erythrocytes with spiny membrane projections) on peripheral smear are a feature of abetalipoproteinemia, which is caused by a mutation in the gene for microsomal triglyceride transfer protein. Abetalipoproteinemia is a rare, usually autosomal recessive, congenital disorder characterized by a complete absence of beta-lipoproteins, steatorrhea, blindness due to retinitis pigmentosa, ataxia, and mental retardation. The complete absence of betalipoproteins means that neither chylomicrons nor VLDL is formed. Massive-dose vitamin A and E therapy has delayed neurologic deterioration in some cases. "Crumpled silk” histiocytes on bone marrow biopsy (**choice B**) suggest Gaucher disease. Globoid cells on brain biopsy (**choice C**) suggest Krabbe disease. Metachromatic deposits on sural nerve biopsy (**choice D**) suggest metachromatic leukodystrophy. "Sea-blue” histiocytes on bone marrow biopsy (**choice E**) suggest Niemann-Pick disease.

Answer 2

Respuesta: D The correct **answer is D**. The most common posterior fossa tumors in children include medulloblastoma, ependymoma, and pilocytic astrocytoma. Medullo-blastoma, an anaplastic neoplasm thought to derive from primitive neuroectodermal precursors, belongs to the group of primitive neuroectodermal tumors (PNET). It originates from the cerebellar vermis and grows into the fourth ventricle, often producing signs and symptoms of increased intracranial pressure. The histologic features are those of other small round cell tumors. Ependymoma (**choice A**) usually derives from the ependymal cells lining the central canal. Childhood ependymomas typically develop in the fourth ventricle and may present with increased intracranial pressure. In contrast to medulloblastoma, however, ependymoma appears on CT/MRI as a mass that fills the fourth ventricle and secondarily involves adjacent structures. Glioblastoma multiforme (GBM; **choice B**) is a rare tumor in children of this age, and the cerebellum is a rare location at any age. Furthermore, GBM grows in a diffuse fashion within the white matter without involving the ventricular cavities. Hemangioblastoma (**choice C**) is a vascular tumor of uncertain histologic origin. The cerebellar hemisphere is its most common location, and it often appears as a cystic mass with a mural nodule. Its association with von Hippel-Lindau syndrome is noteworthy. Oligodendroglioma (**choice E**) is a slow-growing tumor of adults that usually develops in the white matter of a cerebral hemisphere. Calcifications within the tumor are frequently detected on x-ray films or CT scan, and seizures are often the presenting sign. Pilocytic astrocytoma (**choice F**) is a low-grade, well-circumscribed astrocytoma of children and young adults. Cerebellar pilocytic astrocytoma often presents as a cyst with a mural nodule (like hemangioblastoma) within a cerebellar hemisphere. Surgical resection is usually curative.

Answer 3

Respuesta: D The correct **answer is D**. The most likely cause of this infant’s presentation is toxic enterocolitis (toxic megacolon), which is most often seen in the setting of Hirschsprung disease. The disease is suggested in this infant by the delayed passage of meconium, chronic constipation, and the failure to thrive. When unrecognized, putrefaction and development of colitis can occur. In its severest form, it presents as toxic megacolon. The resultant diarrhea, with potentially fatal fluid loss, is due to bacterial overgrowth in the dilated bowel with resulting production of bacterial toxins. Although fluid replacement and antibiotics are important in the management of the these cases, the most helpful therapeutic intervention is prompt surgical resection of the involved bowel with formation of a colostomy. Infants with congenital hypothyroidism (**choice A**) have a history of constipation. However, other features of hypothyroidism are lacking in this case. Classic features include prolonged jaundice, umbilical hernia, macroglossia, hypotonia, and failure of the posterior fontanelle to close. Meconium ileus (**choice B**) occurs in infants with cystic fibrosis who fail to pass meconium in the first few days of life. Necrotizing enterocolitis (**choice C**) is a feared complication of the newborn period, with abdominal distension and sepsis. Volvulus neonatorum (**choice E**) is usually due to a defect in the normal rotation of the bowel in which the caecum remains high, often with a congenital band passing across the duodenum. This results in an intestinal obstruction and vessel occlusion at the base of the mesentery. Clinically, the features of intestinal obstruction predominate, with vomiting, abdominal pain, and constipation. Abdominal radiograph shows a “comma sign” or “beak sign” with absence of distal bowel gas.

Answer 4

Respuesta: B The correct **answer is B**. Roseola is a virus that causes an exanthem (exanthem subitum). It typically affects children between 6 months and 3 years of age. Most cases manifest with a fever (temperature often up to 40-40.5 C) that lasts for 2-3 days; there is often mild erythema of the pharynx and congestion. The discrete, macular rash typically erupts on the trunk with an abrupt end to the fever. Erythema infectiosum (**choice A**), also known as fifth disease, is caused by parvovirus B19. This virus usually affects children aged 5-14 years. There is usually a nonspecific febrile illness with malaise and myalgias lasting 2-3 days. The rash of erythema infectiosum is characterized by a red rash on the cheeks (“slapped” cheeks) and a erythematous maculopapular rash on the extremities and trunk described as a “lacy” reticular pattern. Rubella (**choice C**), also known as German measles, is characterized by a low-grade fever (temperature usually less than 39 C), erythematous maculopapular rash, and lymphadenopathy. Rubeola (**choice D**), or measles, is characterized by 3-5 days of increasing fever, coryza, cough, and conjunctivitis. Koplik spots (white lesions on a red mucosa) appear in the mouth. There is a discrete, erythematous, maculopapular rash that begins on the face and moves downward, covering the trunk and upper and lower extremities. Varicella (**choice E**), or chickenpox, begins with a period of malaise and low-grade fever. The lesions begin as macules and progress to fluid filled vesicles that then crust; the crust eventually falls off. The fever is usually gone by the end of the first week of the rash.

Answer 5

Respuesta: F The correct **answer is F**. The child most likely has Waardenburg syndrome, which is one of the more common craniofacial abnormalities. Defects of this type are related to maldevelopment of the first and second vertebral arches that form the face. The defects usually begin during the second month of gestation. The features illustrated in the question stem are typical. On a practical basis, you should remember that children with white forelocks (partial albinism) should be tested for hearing loss. Beckwith-Wiedermann syndrome (**choice A**) is characterized by macroglossia, a large fontanelle, and a linear fissure in the external ear. Organomegaly of both the pancreas and kidney is common, and omphalocele may be seen at birth. Clinical features of fragile X syndrome (**choice B**) include mental retardation, large testicles, a prominent jaw, large ears, and a large head. The syndrome is caused by a dominant X-linked trinucleotide repeat gene with only a 50% penetrance in females. Features are most prominent in affected males. Goldenhar syndrome (**choice C**) produces an asymmetric face, malformed ears, small eyes, hearing loss, a large mouth, a small mandible, and vertebral anomalies. Pierre Robin syndrome (**choice D**) produces micrognathia, glossoptosis, and cleft palate. Treacher Collins syndrome (**choice E**) is characterized by malformation of the external ear, deafness, micrognathia, antimongoloid eye slanting, and coloboma of the lower eyelids.

Answer 6

Respuesta: C The correct **answer is C**. Herpangina is a caused by coxsackievirus and usually manifests with dysphagia and vesicles on the anterior tonsils and palate. There is typically a history of fever and viral symptoms (runny nose, cough). Diagnosis is made by the presence of small vesicular lesions on the anterior tonsils and posterior palate. Aphthous stomatitis (**choice A**) usually presents with ulcers on the buccal mucosa. There is no associated fever, and the patient does not usually complain of pain. Hand-foot-and-mouth disease (**choice B**) is also caused by coxsackievirus and presents with small vesicles in the mouth, but there are also vesicles on the hands and feet. Commonly, a maculopapular rash is also present. Kawasaki disease (**choice D**) is associated with a history of prolonged fever (more than 5 days), conjunctival erythema, cracked lips, maculopapular rash, cervical lymphadenopathy, and swollen hands. Stevens-Johnson syndrome (**choice E**) is a systemic disease that presents with ulcers over the entire mouth and lips. There usually is a confluent rash on the body as well. The child will appear very ill

Answer 7

Respuesta: C The correct **answer is C**. The infant is having neonatal seizures, which can take a variety of forms. In addition to the migratory clonic jerks described in the question stem, these infants may alternatively experience alternating hemiseizures or primitive subcortical seizures. The later may take the form of respiratory arrest, chewing motions, eye deviations, or changes in muscle tone. True grand mal seizures are usually not seen, possibly because the immaturity of the brain makes it difficult to transmit a seizure to all sites. Neonatal seizures can be seen in a variety of settings, which can be roughly subclassified as primary CNS versus metabolic. The metabolic causes are common, and screening chemistry studies can identify potentially correctable hypoglycemia, hypocalcemia, hypomagnesemia, hypernatremia, or hyponatremia. Consequently, the earliest diagnostic step is to order these appropriate serum screening tests, usually on a STAT basis. CT scan of head (**choice A**), EEG (**choice B**), skull x-rays (**choice D**), and ultrasound of the head (**choice E**) can all be very useful in offering diagnostic clues to true CNS problems, but should be deferred until after the child’s metabolic status is established.

Answer 8

Respuesta: A The correct **answer is A**. At birth, a neonate will typically exhibit some signs of exposure to maternal estrogen. Two of these signs include prominent labia and a dull pink vaginal epithelium. As estrogen levels fall, the labia will become less prominent and the vagina will take on a brighter red appearance. In the absence of other signs or symptoms of disease, these findings are normal and do not require further evaluation. Exposure to penicillin (**choice B**) will almost never cause findings isolated to the labia and vagina. Infection with Chlamydia (**choice C**) can lead to neonatal pneumonia and eye infection. Infection with group B Streptococcus (**choice D**) can cause respiratory distress, pneumonia, meningitis, and sepsis in the newborn. It does not typically cause findings isolated to the genitalia. Sexual abuse (**choice E**) almost always must be considered whenever there are complaints or findings regarding an infant’s genitalia. In this case, however, the infant is newborn-only minutes old. Therefore, sexual abuse would not be in the differential diagnosis.

Answer 9

Respuesta: E The correct **answer is E**. A voiding cystourethrogram (VCUG) is the appropriate test to run to evaluate the lower urinary tract and the presence of any reflux of urine into the kidney. It is appropriate to first wait until the acute infection is over, since there may be some degree of reflux present during an infection. The usual procedure is to wait 1-2 months after treatment to perform the VCUG to evaluate for reflux. Cystoscopy (**choice A**) is not indicated in the evaluation of urinary tract infection. Dimercaptosuccinic acid (DMSA) scan (**choice B**) is a radionuclide renal imaging scan. It might be an appropriate test to diagnosis acute pyelonephritis, but it is not indicated as a first test in evaluating reflux in a urinary tract infection 2 months after the infection. It is the most accurate test to diagnose acute pyelonephritis. Intravenous pyelogram (**choice C**) is rarely used in the pediatric population to evaluate for a urinary tract infection. Performing a VCUG now (**choice D**) would not be appropriate since there might be some degree of reflux present during an acute infection.

Answer 10

Respuesta: D The correct **answer is D**. This is talipes equinovarus, which is the most common form of clubfoot abnormality. The term talipes is used for any deformity of the foot that involves the talus bone. The term equinus refers to a permanent extension of the foot so that only the ball rests on the ground. The term varus refers to a permanent inversion of the foot, so that only the outer side of the sole touches the ground. Talipes equinovarus is best corrected with repetitive casting of the foot beginning at a young age; this approach slowly brings the foot to a more normal position. Epispadias (**choice A**) and hypospadias (**choice B**) are urethral abnormalities. Talipes calcaneovalgus (**choice C**) is associated with a flat and dorsiflexed foot. Torticollis (**choice E**) is head tilt, which can be present at birth as a result of neck trauma

Answer 11

Respuesta: B The correct **answer is B**. Regurgitation of small volumes (usually less than 5-10 mL) is common among babies and is usually of no clinical significance unless the baby is failing to grow normally. It is of concern to some mothers, and switching to a firmer nipple bottle with a smaller hole will slow the rate that the baby is drinking and often reduce the amount of swallowed air. Changing the baby’s formula (**choice A**) does not usually alter the amount of regurgitation. Careful monitoring of the baby (**choice C**), abdominal x-rays (**choice D**), and CT scan (**choice E**) are not warranted for this benign condition.

Answer 12

Respuesta: E The correct **answer is E.** This 3-year-old girl has steatorrhea, recurrent diarrhea, and failure to thrive. There is a family history of an uncle who died of recurrent lower respiratory infections. This patient most likely has cystic fibrosis (CF). The gastrointestinal system is significantly affected by CF. Gastrointestinal manifestations are caused by pancreatic exocrine insufficiency, which occurs in more than 85% of patients with CF. The mutation of the CF gene causes inspissation of pancreatic secretions and obstruction of the ductules. It causes the malabsorption of protein and fat, resulting in steatorrhea. Untreated pancreatic insufficiency results in malnutrition and failure to thrive. The treatment is to replace the missing pancreatic enzymes by oral supplementation of purified pancreatic enzymes (pancrelipase) with food. Several capsules are taken with each meal and snack. Even with pancreatic enzyme replacement, however, there might still be mild steatorrhea. Fat-soluble vitamins, such as A, D, E, and K, are also supplemented in these patients to avoid fat-soluble vitamin deficiency. Successful nutritional management is an important part of the overall management of CF, because good nutritional status improves the overall prognosis and decreases the frequency of pulmonary infections. Avoidance of dairy products (**choice A**) is useful in diarrhea caused by lactose intolerance but not in CF. Elimination of dietary fat (**choice B**) is inappropriate. In fact, the intake of fat should be encouraged because the fat content increases palatability and provides high calories to the patient’s body. Dietary fat is also essential for the absorption of fat-soluble vitamins. A ketogenic diet (**choice C**) has no role in the management of CF. It is sometimes used to control epilepsy. Oral metronidazole (**choice D**) is effective against anaerobic bacterial infection. It can be useful in bacterial overgrowth in the intestine and in Clostridium difficile colitis, but it has no role in the treatment of pancreatic insufficiency.

Answer 13

Respuesta: B The correct **answer is B**. The boy in this clinical vignette has staphylococcal scalded skin syndrome (SSSS). It is characterized by fever, malaise, and a generalized fine erythematous rash. It is then followed by crusty, sometimes exudative, lesions around the mouth and eyes. It is usually preceded by an upper respiratory infection. The skin is tender to touch. With gentle rubbing, the epidermal layer can exfoliate, which is the characteristic Nikolsky sign. This syndrome is caused by an exfoliative toxin secreted by certain strains (55 and 71) of Staphylococcus aureus. Sometimes, injection of the conjunctiva and fissuring of the lips can happen and might be confused with Kawasaki disease. The differential diagnosis includes toxic shock syndrome, scarlet fever, and toxic epidermal necrolysis. Nafcillin or oxacillin can be used to treat SSSS. Kawasaki disease (**choice A**) involves vasculitis of epicardial coronary vessels, with possible development of aneurysm. The clinical syndrome presents with fever longer than 5 days, bilateral conjunctival injection, mucosal change in the oral pharynx, erythema of hands and feet with desquamation, and cervical lymphadenopathy. Transient arthritis may also occur. Streptococcal scarlet fever (**choice C**) usually presents with an erythematous sandpaper-like rash with fever and “strawberry tongue.” It is caused by erythrogenic exotoxins secreted by group A Streptococcus. It is usually associated with streptococcal pharyngitis. Toxic epidermal necrolysis (**choice D**) is a dermatologic emergency characterized by widespread epidermal necrosis and desquamation after formation of blisters and bullae. It is caused by a severe hypersensitivity reaction, usually to a drug. Major complications include sepsis, dehydration, and shock. Patients should be treated as if they have a generalized severe burn. Toxic shock syndrome (**choice E**) is caused by an exotoxin (TSST1) of Staphylococcus aureus, or less commonly, Streptococcus pyogenes. Patients present with high fever, myalgia, pharyngitis, abdominal pain, vomiting, diarrhea, headache, and a diffuse, sunburn-like rash. Severe cases are complicated by hypotension, shock, and renal failure.

Answer 14

Respuesta: E The correct **answer is E**. Alkaline burns are extremely destructive, and the process of destruction continues as long as the agent is in contact with the tissues. Immediate removal is essential, and the best way to do it is with massive irrigation. In the emergency department, sterile saline would be used; at home, tap water will do. Antibiotics (**choice A**) do not help, and a leisurely approach will guarantee loss of the eye. Rushing to the hospital (**choice B**) might seem like the thing to do for all kinds of emergencies, but in this case immediate first aid is more important. If the corrosive substance remains in the eye during the trip to the emergency department, the eye will be destroyed by the time the patient arrives. "Playing chemist” (**choice C**) is never acceptable because of the possibility of causing an exothermic reaction. Swiping with a tissue (**choice D**) would be better than nothing, but not by much. Swiping has a role, but not as the first thing to do. After massive irrigation, little particulate matter may remain, which may then have to be mechanically swiped away.

Answer 15

Respuesta: C The correct **answer is C**. The child has body lice, Pediculus humanus corporis, which live in the clothing and cause itchy bites. The structures on the clothing seams are the eggs. The lice themselves can also often be seen. The lice are confined to the skin surface, and, unlike scabies mites, do not burrow into the skin. The patient, family members, and social contacts (such as other daycare children) should all be treated at the same time with permethrin cream, 5%. Clothing and bedding should also be washed. Ancylostoma braziliense (**choice A**) causes cutaneous larva migrans, which produces long itchy burrows on the legs and buttocks. Corynebacterium minutissimum (**choice B**) causes erythrasma, characterized by pink to brown itchy patches in moist areas of skin. Sarcoptes scabiei (**choice D**) causes scabies, which is diagnosed by finding fine white lines up to 1 cm in length (burrows) in the skin, with a mite at the end of them. Trichophyton rubrum (**choice E**) is a fungus that can cause ringworm of the body

Answer 16

Respuesta: D The correct **answer is D**. Bleeding from the ear following an injury to the skull is pathognomonic of a temporal bone fracture. The bleeding can be medial to an intact tympanic membrane, from the middle ear through a rupture of the tympanic membrane, or from a fracture line in the ear canal. Hemotympanum gives the tympanic membrane a blue-black color. Usually, there is a communication with the subarachnoid space through the fracture line. Often, there is cerebrospinal fluid otorrhea. Cleaning of the ear canal should be avoided for fear of introducing microorganisms. The immediate danger to the patient is the development of meningitis. Prophylactic antibiotic therapy has to be initiated immediately. Most fractures of the temporal bone are longitudinal (80%) to the long axis of the petrous pyramid. Only 20% are transverse. Longitudinal fractures usually extend through the middle ear into the ear canal, causing rupture of the tympanic membrane. Approximately 35% of longitudinal fractures produce a sensorineural hearing loss, and approximately 15% produce facial paralysis. Transverse fractures extend across the cochlea and fallopian canal, causing a profound, permanent sensorineural hearing loss and a facial paralysis. These fractures are usually well demonstrated with CT. Concussion (**choice A**) is a syndrome of alteration of consciousness secondary to head injury, typically brought about by a sudden change in the momentum of the head. Its usual manifestations include loss of consciousness, temporary respiratory arrest, and loss of reflexes. Epidural hematomas (**choice B**) are blood clots that form between the inner table of the skull and the dura. Eighty percent are associated with skull fractures across the middle meningeal artery or across a dural sinus. The high arterial pressure of the bleeding vessel dissects the dura away from the skull, permitting the formation of the hematoma. The incidence of skull fractures in children with epidural hematomas is lower than in adults because of the elasticity of the skull. Subdural hematoma (**choice C**) usually results from trauma involving acceleration or deceleration head injury and is commonly associated with parenchymal brain injury. Tympanic membrane perforation (**choice E**) most commonly happens after an object is inserted into the ear canal and perforates the eardrum.

Answer 17

Respuesta: B The correct **answer is B**. Primary amenorrhea is defined as the absence of menses by the age of 16, or 4 years after thelarche (the onset of breast development). The prevalence of primary amenorrhea is 1% to 2%. In this country, the median age of menarche is 12.5 years. Most girls have menarche about 2 years after thelarche. Primary amenorrhea is different from secondary amenorrhea, which is defined as the absence of menses for three menstrual cycles or a maximum of 6 months in women who previously had normal menstruation. Primary amenorrhea has a vast differential diagnosis and is usually divided into three categories: 1) outflow tract anomalies (e.g., imperforate hymen, transverse vaginal septum, vaginal agenesis, testicular feminization); 2) end-organ disorders (e.g., ovarian failure, gonadal agenesis with 46,XY chromosomes); and 3) central disorders (e.g., hypothalamic disorders, pituitary disorders). The age of the adolescent girl in this scenario is consistent with primary amenorrhea. Her sexual maturation is progressing appropriately. It is most likely that she has physiologic pubertal delay because the pelvic ultrasonography is normal. She probably has not completed her pubertal development. Imperforate hymen (**choice A**) does not allow egress of menses. Patients usually present with pelvic pain from the accumulation of menses and dilatation of the uterus. Physical examination reveals a bulging membrane across the introitus and a midline pelvic mass. Prolactinoma (**choice C**) can cause headache, decreased growth rate, galactorrhea, delayed puberty, primary or secondary amenorrhea, gynecomastia, and visual field defects. Testicular feminization syndrome (**choice D**) is caused by either dysfunction or total absence of the testosterone receptor and results in a phenotypical female with 46,XY chromosomes. Patients with testicular feminization will have normal breast development but lack pubic hair. Pelvic ultrasound would reveal agenesis of the vagina and uterus. In Turner syndrome (45,XO; **choice E**), the ovaries undergo rapid atresia; by puberty, there are no primordial oocytes.

Answer 18

Respuesta: A The correct **answer is A**. Food allergy-induced colitis is a clinical syndrome of enterocolitis usually presenting between 1 week and 3 months of age. The dietary proteins implicated are generally cow’s milk or soy proteins. Although diarrhea and emesis are the most prominent symptoms, rectal bleeding, protein-losing enteropathy with edema, and dehydration with metabolic acidosis are also prominent. The diarrhea is relatively acute and progressive to the point of dehydration if the etiologic protein is not eliminated. The stools contain mucus, polymorphonuclear leukocytes, and eosinophils. Rectal bleeding progresses from occult to increasingly gross bleeding and anemia. Whereas the diarrhea is most consistent with an inflammatory colitis, stools may also contain reducing sugars, suggesting a small intestinal component as well. Approximately one third of infants with severe diarrhea will develop metabolic acidosis. Hypotension may complicate the presentation in younger infants but is more commonly seen following protein challenge, especially with soy. Irritability, emesis, and abdominal distention are also prominent with acute manifestations. When a more indolent clinical course is encountered, the infant will manifest failure to thrive, edema from enteric protein loss, and anemia. Food refusal, a feature of eosinophilic esophagitis and enteropathy, is also common. The diagnosis is confirmed when symptoms resolve within 72-96 hours after the elimination of the offending protein from the diet, and subsequent oral challenge provokes both symptoms and a measurable inflammatory response. More than 90% of the infants will respond to initiation of an extensively hydrolyzed casein-based formula. From 15% to 50% of infants sensitive to cow’s milk will also be sensitive to soy-based formula. Meckel diverticulum (**choice B**) is the most common congenital malformation of the gastrointestinal tract, occurring in about 1.5% of the general population, most of whom experience no symptoms. The mucosa is often gastric, and the acid secreted may cause ulceration and bleeding, which is usually painless. Necrotizing enterocolitis (**choice C**) affects premature infants and usually occurs as a complication of respiratory distress syndrome or patent ductus arteriosus. It manifests as abdominal distention, tenderness, bilious vomiting, and occult or frank blood in stool. Rectal fissure (**choice D**) is one of the most common causes of rectal bleeding in young children. There is usually a history of constipation, with passage of large and hard stools. Ulcerative colitis (**choice E**) is an inflammatory bowel disease primarily affecting the colon. It causes abdominal pain, hematochezia, diarrhea, weight loss, and fever.

Answer 19

Respuesta: A The correct **answer is A.** Acute otitis media and acute sinusitis are among the most common infectious conditions of childhood. Acute sinusitis usually follows a common cold and is due to bacterial infection of the maxillary sinuses. It manifests with persistent mucopurulent discharge, daytime coughing without wheezing, and nasal obstruction. The diagnosis is based on a temporal criterion, with such manifestations present for at least 10 days. The 10-day mark allows differentiation of acute sinusitis from acute viral rhinitis (**choice C**), which should resolve within a week or so. If nasal discharge and obstruction persist for more than 30 days, the diagnosis is subacute sinusitis. High fever, swelling of eyelids, and pain on slight pressure over the sinuses indicate a severe sinus infection that needs prompt evaluation and aggressive antibiotic treatment. Most cases of acute sinusitis resolve after antibiotic treatment with amoxicillin or a macrolide, plus topical vasoconstrictors and nasal saline lavage for symptomatic relief. Acute otitis media (**choice B**) usually follows an upper respiratory infection. It is characterized by otalgia (especially in older children) and the otoscopic findings of bulging and fullness of the tympanic membrane. Acute otitis media is more frequent between 6 months and 3 years of age. Allergic rhinosinusitis (**choice D**) manifests with chronic clear nasal discharge, without fever or pain. There is usually an accompanying history of allergies. Asthma (**choice E**) is characterized by paroxysmal attacks of respiratory distress with tachypnea and wheezing. Cough and increased nasal secretion may be present

Answer 20

Respuesta: B The correct **answer is B**. The most crucial step in the management of asthma is avoidance of triggering factors, e.g., allergens. Unfortunately, it is difficult to avoid specific types of allergens, such as pollens. Specific measures to eliminate or reduce exposure to dust mites and animal dander at home lead to reduced frequency of attacks and hospitalization rates. Regardless of the allergens involved, elimination of respiratory irritants, especially cigarette smoke, is of crucial importance. The bronchial tree of asthmatic patients is highly reactive to any form of chemical or physical irritation. Thus, exposure to passive smoke should be absolutely avoided. Avoidance of exercise (**choice A)** is not an appropriate measure, although exercise frequently triggers asthmatic attacks. The efficacy of anti-asthma measures can be evaluated by observing how the child can sustain adequate forms of exercise. Use of a humidifier at home (**choice C**) will favor growth of dust mites and consequently increase the concentration of these allergens in the environment. Use of air cleaners at home (**choice D**) has not been shown to be uniformly effective in getting rid of dust mites. Administration of multiple-drug regimens (**choice E**) is not a recommended strategy in the pharmacologic treatment of asthma. In fact, the fewest number of drugs at the lowest effective doses should be used. Typically, a regimen of one drug (a bronchodilator or a inhaled corticosteroid) for mild-moderate cases or two drugs for more severe cases is sufficient to control asthma exacerbations. Immunotherapy against identified allergens (**choice F**) is of some benefit when a single allergen is involved, but not with multiple airborne allergens.

Answer 21

Respuesta: A The correct **answer is A**. Mental retardation associated with abnormal facial features may be related to abnormal genetics. As our skill with DNA analysis has improved, we have identified a number of microdeletion syndromes involving contiguous genes on a single chromosome that are associated with mental retardation and often distinctive clinical presentations. The case illustrated is Williams syndrome, which involves 7q11.23. 20p12 (**choice B**) is associated with Alagille syndrome, characterized by lack of bile ducts, cardiac abnormalities, butterfly vertebrae, and eye abnormalities. 22q11.21 (**choice C**) is associated with DiGeorge syndrome, which is characterized by thymus and parathyroid abnormalities, heart defects, cleft palate, and mental retardation. Involvement of the maternal chromosome 15 at 15q11 (**choice D**) is associated with Angelman syndrome, which is characterized by seizures, puppet-like movements, outbursts of laughter, and severe mental retardation. Involvement of the paternal chromosome 15 at 15q11 (**choice E**) is associated with Prader-Willi syndrome, which is characterized by obesity, small hands and feet, and mental retardation.

Answer 22

Respuesta: C The correct **answer is C**. This infant has neonatal chlamydial infection that was acquired during birth from an infected mother. The major manifestation presented in this case is chlamydial ophthalmia, which occurs in about 30 to 40% of infants born to infected mothers. The severity of chlamydial ophthalmia can range from mild conjunctivitis to the severe pattern described in the question stem. Follicles are not present in the conjunctiva; they appear in in older children and adults. Chlamydial ophthalmia becomes evident 5 to 14 days after birth. Many of these infants also have nasopharyngeal colonization with Chlamydia, and neonatal pneumonia is common in patients who have clinically developed conjunctivitis. Symptoms of chlamydial pneumonia typically occur within 2 to 19 weeks, with an insidious onset of staccato cough. Gonorrheal ophthalmia produces an acute purulent conjunctivitis that appears 2 to 5 days after birth or earlier with premature rupture of membranes. It can rapidly lead to corneal ulceration (**choice A**) and perforation if treatment is delayed. Serious systemic complications, such as encephalitis (**choice B**), can result from herpes simplex keratocon-junctivits because these infants have poor immunologic response to the generalized herpes infection. Sepsis (**choice D**) can be a complication of conjunctivitis, but it is less specific to chlamydial ophthalmia compared with other types of bacterial conjunctivitis. The risk for chlamydial pneumonia is more significant in this patient. A chemical conjunctivitis may result from prophylactic silver nitrate use in neonates. It usually appears within 6 to 8 hours after installation and disappears spontaneously within 24 to 48 hours. Silver toxicity (**choice E**) is not typical of prophylactic silver nitrate use, and it is unrelated to chlamydial ophthalmia.

Answer 23

Respuesta: A The correct **answer is A**. Apnea can be a life-threatening complication of RSV infection in infants younger than 1 year. For this reason, infants with respiratory distress and either laboratory confirmation or a clinical picture suggestive of RSV infection are often admitted to the hospital for supportive care and monitoring. Congestive heart failure (**choice B**) is not associated with RSV infection in a child with normal cardiac function. Infants are obligate nose-breathers and may have difficulty feeding because of nasal congestion. In the face of respiratory distress, infants have increased insensible fluid losses and are at risk for dehydration (**choice C**). Dehydration, however, is not the most severe risk for this child. Hypoxemia (**choice D**) and cyanosis may result from mucous plugging of the lower bronchial tree, atelectasis, and mismatch in infants with acute RSV infection. The hypoxemia is usually transient and not life-threatening. Hypoxemia is readily corrected with supplemental oxygen administration. Wheezing (**choice E**) is a very common sign of RSV infection. It signifies inflammation of the bronchioles, but it is not lifethreatening.

Answer 24

Respuesta: B The correct **answer is B**. Ewing sarcoma (ES) is the second most common bone cancer in childhood and adolescence. It has a peak age incidence during adolescent years. It rarely occurs in blacks and is more prevalent in boys than girls. ES may have histopathologic features characteristic of neural differentiation; ES is thought to be a tumor of neural origin, whereas most bone tumors are thought to be of mesodermal origin. The tumor category of ES has recently been expanded to include more neural tumors, such as peripheral primitive neuroectodermal tumor (PNET). Like other bone tumors, ES is associated with a consistent chromosomal translocation, t(11;22)(q24;q12), which occurs in about 90 to 95% of cases. Chondroblastoma (**choice A**) is a very rare bone tumor that most often occurs in the pelvis. Histopathology reveals cartilaginous tumor tissue with malignant spindle cells. Neuroblastoma (**choice C**) is a common solid tumor of childhood that typically occurs during the first few years of life. Histologically it is a small round cell tumor with characteristic Homer-Wright rosettes. It displays neural differentiation and therefore might initially be confused with ES, but it is not a bone tumor. It usually occurs in the neck, thorax, abdomen, or flank. Osteosarcoma (**choice D**) is the most common bone cancer of childhood and adolescence. Like ES, osteosarcoma may involve the bones of the leg, especially the femur, and frequently metastases to the lungs. Osteosarcoma is known to be associated with certain genetic conditions, such as osteogenic imperfecta, and there is an increased occurrence of osteosarcoma in children with retinoblastoma. It occurs in all races. Pathologically, neural differentiation is not observed. Rhabdomyosarcoma (**choice E**) is the most common soft tissue sarcoma of childhood. It does occur more frequently among males and whites, but it is usually found in the head and neck areas and the genitourinary tract. Like neuroblastoma and ES it is a small round cell tumor. It does not display neural differentiation. It may first be noticed after trauma as in this case, but there is no bony involvement.

Answer 25

Respuesta: C The correct **answer is C**. Febrile seizures are common events. This form of benign manifestation affects approximately 3 to 4% of children. Since epilepsy is defined as at least two seizures occurring without an identifiable trigger, febrile seizures do not constitute epilepsy even if they recur. Fever, in fact, is the identifiable trigger. Most children who have an episode of febrile seizure will not have a recurrence. Risk factors that do increase the likelihood of recurrence include family history, age younger than 18 months (**choice A**), and temperature less than 39.0 C (**choice E**) when seizure occurred. Overall, children with a first febrile seizure will have a recurrence in 25% of cases by 1 year and in 30% by 2 years. The duration of the first seizure (**choice B**) will not influence the likelihood of recurrence, but recurrences will likely also be prolonged if the first episode lasted for more than 15 minutes. Fever of long duration (**choice D**) is negatively correlated to the probability of recurrences.

Answer 26

Respuesta: C The correct **answer is C.** Measurements of T4 and TSH levels are the most appropriate tests to confirm congenital hypothyroidism. Alpha1 antitrypsin genotyping (**choice A**) is used to confirm alpha1 antitrypsin deficiency. A liver and spleen scan (**choice B**) is useful to indicate absence of the biliary tree or blockage of the extrahepatic bile ducts and is therefore most useful to confirm biliary atresia. Barium swallow (**choice D**) will indicate the presence of pyloric stenosis (“string” sign = narrowing of barium stream passing through the duodenum; “umbrella” sign = the hold-up of barium in the stomach). The RPR and FTA (**choice E**) are serologic tests for syphilis.