An 11-year-old boy is brought to the emergency department by his mother due to a week of fever, malaise, productive cough, and worsening dyspnea. The patient has cystic fibrosis that was diagnosed at birth and has since had recurrent episodes of sinusitis and lung infections. He has no other chronic medical conditions and is up to date on all recommended vaccinations. Temperature is 38.5 C (101.3 F), pulse is 110/min, and respirations are 30/min. Oxygen saturation is 92% on room air. Auscultation of the lungs reveals bilateral fine crackles and rhonchi. The patient is admitted to the hospital, and broad-spectrum antibiotics are started. A week later, there is no improvement in symptoms. Laboratory studies reveal peripheral blood eosinophilia and an IgE level of 3,225 IU/mL. Which of the following is the most likely cause of this patient's current condition?

Question

An 11-year-old boy is brought to the emergency department by his mother due to a week of fever, malaise, productive cough, and worsening dyspnea.  The patient has cystic fibrosis that was diagnosed at birth and has since had recurrent episodes of sinusitis and lung infections.  He has no other chronic medical conditions and is up to date on all recommended vaccinations.  Temperature is 38.5 C (101.3 F), pulse is 110/min, and respirations are 30/min.  Oxygen saturation is 92% on room air.  Auscultation of the lungs reveals bilateral fine crackles and rhonchi.  The patient is admitted to the hospital, and broad-spectrum antibiotics are started.  A week later, there is no improvement in symptoms.  Laboratory studies reveal peripheral blood eosinophilia and an IgE level of 3,225 IU/mL.  Which of the following is the most likely cause of this patient's current condition?

Quizplus · Accepted Answer

11ec25c8_d718_db56_bc81_4126d3bf542b_MD0003_00 This patient with cystic fibrosis (CF) has nonresolving symptoms of lower respiratory inflammation, eosinophilia, and high IgE (eg, >1,000 IU/mL), findings consistent with allergic bronchopulmonary aspergillosis (ABPA). Aspergillus species, usually A fumigatus, are ubiquitous environmental fungi, continually inhaled and cleared by natural lung defenses (eg, mucociliary escalator). In patients with structural airway disease (eg, asthma, CF), recurrent infections and mucus trapping lead to chronic colonization and hypersensitization to fungus spores (eg, Aspergillus). This promotes a Th2-based allergic response, driving production of IgE and eosinophilia. ABPA may be indistinguishable from underlying CF bronchopneumonia. Fever, malaise, and thick, blood-streaked sputum are common. ABPA must be suspected if there is an unexplained lung function decline despite an appropriate antibiotic course (>1 wk). Diagnosis includes evidence of Aspergillus-specific sensitization (eg, positive skin testing, specific IgE) and chest radiology showing bronchiectasis and mucus plugging (eg, intrabronchial exudates appearing as tubular, finger-in-glove radiodensities). In patients with CF, routine annual ABPA screening with total serum IgE is recommended. Treatment includes systemic glucocorticoids to decrease allergic inflammation and antifungal therapy (eg, voriconazole) to reduce spore burden. (Choice B) Granulomatosis with polyangiitis can cause constitutional symptoms (fever, malaise) and necrotizing bronchiectasis, mimicking infectious pneumonia unresponsive to antibiotic therapy. However, it typically affects men age >60 and is not associated with elevated IgE or eosinophilia. (Choice C) Acute hypersensitivity pneumonitis can cause fever, malaise, and pneumonia-like airspace infiltrates unresponsive to antibiotic therapy. Pneumonitis typically improves spontaneously in the hospital (patient removed from inciting exposure). Eosinophilia and high IgE are not expected. (Choice D) Simple (nondisseminated) strongyloidiasis is a helminthic infection that can cause eosinophilic pulmonary disease (ie, infiltrates with peripheral eosinophilia) and elevated IgE. However, it usually occurs in rural tropical and subtropical areas; in addition, because larvae penetrate the skin and are eventually swallowed, patients usually also have dermatologic (roaming urticaria) and gastrointestinal (obstruction, ileus) manifestations. (Choice E) Patients with CF bronchiectasis can be colonized and infected with nontuberculous mycobacteria (NTM) such as Mycobacterium avium complex (not M tuberculosis). However, NTM disease is chronic (months to years) and presents with nodular, cavitary, and, eventually, fibrotic lung disease. Eosinophilia and elevated IgE are not characteristic. Educational objective: Patients with structural airway disease, especially cystic fibrosis and asthma, are susceptible to allergic bronchopulmonary aspergillosis (ABPA). Allergic sensitization to Aspergillus spores is signified by high levels of circulating IgE. ABPA must be suspected when lung function declines without explanation, or persistent lower respiratory infection symptoms occur despite adequate antibiotic therapy.

An 11-Year-Old Boy Is Brought to the Emergency Department by His