Question 36
A 44-year-old previously healthy man has the sudden onset of severe dyspnea. On physical examination he is afebrile. There are absent breath sounds over the right lung fields. A chest x-ray shows pulmonary atelectasis involving all of the right lung. Which of the following conditions is most likely to produce these findings?
A Aspiration of a foreign body
B Pulmonary embolism
C Squamous cell carcinoma
D Penetrating chest trauma
E Bronchiectasis
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(D) CORRECT. This would lead to pneumothorax with lung collapse. Such trauma is not infrequent, particularly in auto accidents.
(A) Incorrect. Although atelectasis can occur distal to bronchial obstruction, it would be unusual for a foreign body to occlude a mainstem bronchus. The resorption of air is not immediate.
(B) Incorrect. Occlusion of pulmonary arterial circulation does not collapse a lung.
(C) Incorrect. It is possible, but a neoplasm would more likely occlude just part of the bronchial tree.
(E) Incorrect. The bronchial obstruction is accompanied by inflammation, and the net result is bronchial dilation. Atelectasis is focal.
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Question 37
A newborn male infant develops increasing respiratory distress within an hour following an uncomplicated vaginal delivery at 36 weeks gestation. A plain film radiograph reveals near opacification of both lungs. Despite intubation and positive pressure ventilation, the baby dies within two days. At autopsy, the infant's lungs demonstrate extensive pink hyaline membranes. Which of the following maternal conditions is most likely to increase the risk for this infant's respiratory distress?
A Gestational diabetes
B Hyperemesis gravidarum
C Iron deficiency
D Preeclampsia
E Systemic lupus erythematosus
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(A) CORRECT. The hyperinsulinism in the baby as a result of the high glucose impedes development of the type II pneumonocytes. By 36 weeks there should normally be sufficient surfactant to prevent hyaline membrane disease. Tests for fetal lung maturity include the L/S ratio, fluorescence polarization (fpol), and phosphatidyl glycerol (PG).
(B) Incorrect. Hyperememsis is 'morning sickness' which makes the mother feel miserable, but does not affect fetal lung maturity.
(C) Incorrect. Iron deficiency leads to maternal and infantile anemia, but does not affect fetal lung maturity.
(D) Incorrect. Preeclampsia may lead to premature delivery, but at 36 weeks this infant's lungs should have sufficient surfactant production.
(E) Incorrect. SLE does not directly affect fetal lung maturity.
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Question 38
Following an acute pharyngitis lasting 4 days, a 10-year-old boy develops neck pain and marked halitosis. On physical examination is breath is very malodorous. A CT scan shows an abscess in the peritonsillar region. Laboratory studies include a culture of the abscess which grows anaerobic flora. Which of the following aerobic organisms is most likely to be cultured from his abscess?
A Staphylococcus aureus
B Hemophilus influenzae
C Corynebacterium diphtheriae
D Bordetella pertussis
E Group A Streptococcus
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(E) CORRECT. A peritonsillar abscess is usually a complication of a strep throat.
(A) Incorrect. Staphylococcal infections of the pharynx are not common in children.
(B) Incorrect. Hemophilus more typically produces an epiglottitis that may be obstructive. It can also lead to pneumonia and to meningitis.
(C) Incorrect. Diptheria is rare nowadays due to immunization. In the acute disease there is a pseudomembrane that is formed, not an abscess.
(D) Incorrect. This is the causative agent for whooping cough, which is rare because of immunization. There is a laryngotracheobronchitis, but rarely mucosal erosion.
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Question 39
A 65-year-old man has had no major medical problems prior to the past year, when he noted increasing malaise along with an 8 kg weight loss. He is a non-smoker. He currently does not have fever, cough, dyspnea, or any respiratory difficulties. On physical examination, he has non-tender supraclavicular lymphadenopathy. The lungs are clear to auscultation. A chest x-ray shows multiple solid nodules ranging from 1 to 3 cm scattered throughout all lung fields. No infiltrates or areas of consolidation are noted. Laboratory studies show Hgb 11.6 g/dL, Hct 34.7%, MCV 83 fL, and WBC count 6280/microliter. Which of the following pathologic processes in his lungs is most likely to account for these findings?
A Pulmonary infarctions
B Foreign body aspiration
C Metastatic carcinoma
D Nocardia asteroides infection
E Silicosis
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(C) CORRECT. Multiple masses should suggest metastases, rather than a primary lung tumor. His lack of a cough or fever is against an infectious cause or aspiration.
(A) Incorrect. Infarctions tend to be pleural based and resolve over weeks. The thromboemboli producing multiple infarctions should cause dyspnea and lead to cor pulmonale.
(B) Incorrect. Aspiration of a foreign body is an acute event that can produce focal atelectasis and/or pneumonia with possible abscess, not multiple masses.
(D) Incorrect. Nocardiosis is typically seen in immunocompromised patients and leads to abscess formation.
(E) Incorrect. Silicosis severe enough to produce lung nodules should lead to a restrictive lung disease with dyspnea.
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Question 40
A 43-year-old woman who does not smoke becomes increasingly dyspneic over 8 years' time. She does not have a cough or increased sputum production. She is afebrile. On physical examination she has decreased breath sounds with hyperresonance in all lung fields. A chest radiograph reveals increased lucency of all lung fields. Laboratory studies show her serum alpha-1-antitrypsin level is 18 mg/dL. Which of the following microscopic portions of the lung is most likely to be affected by her condition?
A Lymphatic channel
B Alveolar duct
C Bronchial artery
D Interstitium
E Terminal bronchiole
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(B) CORRECT. Alpha-1-antitrypsin (AAT) deficiency leads to a panacinar form of emphysema which involves the distal acinus beyond the respiratory bronchiole.
(A) Incorrect. The lung lymphatics are not directly affected by emphysema.
(C) Incorrect. The bronchial arteries supply systemic blood to the lung, primarily in the intersitium, and are not directly affected by emphysematous processes.
(D) Incorrect. The intersititium may appear more prominent with emphysema when there is collapse following loss of alveoli.
(E) Incorrect. Alpha-1-antitrypsin deficiency leads to a panacinar form of emphysema with the bulk of the damage distal to the respiratory bronchiole.
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