An 18-year-old man is admitted to the hospital with cough, fever, and hypoxemia. Despite multiple intravenous antibiotics and frequent chest physiotherapy, the patient decompensates and is transferred to the intensive care unit for mechanical ventilation. Sputum cultures grow 100,000 colony-forming units of a non-lactose-fermenting gram-negative rod. After several days, the patient dies of overwhelming pneumonia complicated by respiratory failure. Since age 1, he had been hospitalized for recurrent episodes of multi-lobar pneumonia, sinusitis, and poor growth. On autopsy, both vas deferens are absent. Which of the following findings is also likely to be present on autopsy?

Question

An 18-year-old man is admitted to the hospital with cough, fever, and hypoxemia.  Despite multiple intravenous antibiotics and frequent chest physiotherapy, the patient decompensates and is transferred to the intensive care unit for mechanical ventilation.  Sputum cultures grow >100,000 colony-forming units of a non-lactose-fermenting gram-negative rod.  After several days, the patient dies of overwhelming pneumonia complicated by respiratory failure.  Since age 1, he had been hospitalized for recurrent episodes of multi-lobar pneumonia, sinusitis, and poor growth.  On autopsy, both vas deferens are absent.  Which of the following findings is also likely to be present on autopsy?

Quizplus · Accepted Answer

11ec160b_393e_546c_9249_231bfc407e35_MD0001_00 Cystic fibrosis transmembrane conductance regulator (CFTR) normally allows for transport of chloride into gastrointestinal and respiratory lumens, followed by sodium and water, leading to thin mucus. In cystic fibrosis (CF), the dysfunctional or absent CFTR gene leads to decreased water within the lumen, resulting in thick, dehydrated, and viscous mucus within organs. This patient's recurrent sinopulmonary infections and congenital absence of the vas deferens are consistent with CF. Pneumonia due to a non-lactose-fermenting, gram-negative rod (Pseudomonas aeruginosa or Burkholderia cepacia) is very common. The most common gastrointestinal manifestation of CF is pancreatic insufficiency (PI). Pancreatic duct obstruction and distension due to viscous mucus and subsequent inflammation develop in utero, eventually leading to fibrosis. PI is present from birth in most patients with CF. The loss of pancreatic tissue prevents these patients from developing pancreatitis. PI results in inability to absorb fats and fat-soluble vitamins (ADEK), leading to steatorrhea and failure to thrive. Patients with PI require pancreatic enzyme supplementation. (Choice B) Bronchopulmonary sequestration is a congenital malformation characterized by extra, nonfunctional lung tissue without communication to the tracheobronchial tree. The extra tissue can be within a lung lobe or outside of the lungs and can present as recurrent pneumonia in the same focal site. (Choice C) Lymphocytic infiltration of pancreatic islet cells is seen in the pathogenesis of type 1 diabetes mellitus. One or more autoantigens within these cells serves as a target for autoimmune attack, eventually leading to destruction of insulin-producing pancreatic cells. (Choice D) Nodular lymphoid hyperplasia of the intestine is classically seen in common variable immunodeficiency syndrome (CVID), a disorder of low immunoglobulin and B lymphocyte levels that predisposes to recurrent sinopulmonary and gastrointestinal infections. Congenital absence of the vas deferens is not associated with CVID. (Choice E) Situs inversus refers to transposition of the major internal organs (eg, dextrocardia). It is associated with primary ciliary dyskinesia (or Kartagener syndrome), in which inefficient cilia in multiple organs fail to beat synchronously and clear mucus. Recurrent sinopulmonary infections and bronchiectasis result, but absence of the vas deferens does not occur. Educational objective: The most common gastrointestinal disorder in patients with cystic fibrosis is pancreatic insufficiency. Mutations in the cystic fibrosis transmembrane conductance regulator gene lead to thick, viscous secretions in the lumens of the pancreas, resulting in obstruction, inflammation, and subsequent fibrosis. Clinical manifestations include steatorrhea, failure to thrive, and deficiency of fat-soluble vitamins. __________ References: Cystic fibrosis. (http://www.ncbi.nlm.nih.gov/pubmed/19403164) Gastrointestinal disorders in cystic fibrosis. (http://www.ncbi.nlm.nih.gov/pubmed/26857772)

An 18-Year-Old Man Is Admitted to the Hospital with Cough