A 19-year-old woman comes to the emergency department due to shortness of breath. The patient has a history of cystic fibrosis and underwent bilateral lung transplant 3 months ago. Over the past 4 days, she has developed worsening tachypnea and now feels unable to catch her breath. The patient reports that fever started this morning. Medications include prednisone, tacrolimus, mycophenolate, trimethoprim-sulfamethoxazole, and pancreatic enzyme supplements. Temperature is 38.7 C (101.7 F), blood pressure is 125/86 mm Hg, pulse is 108/min, and respirations are 26/min. On examination, there is moderate respiratory distress with subcostal retractions and tachypnea. Lung auscultation demonstrates diffuse crackles bilaterally. There are no murmurs, rubs, or gallops. The abdomen is soft and nontender. Chest x-ray reveals diffuse interstitial infiltrates and a small amount of fluid at the bilateral lung bases. Which of the following is the most likely etiology of this patient's presentation?

Question

A 19-year-old woman comes to the emergency department due to shortness of breath.  The patient has a history of cystic fibrosis and underwent bilateral lung transplant 3 months ago.  Over the past 4 days, she has developed worsening tachypnea and now feels unable to catch her breath.  The patient reports that fever started this morning.  Medications include prednisone, tacrolimus, mycophenolate, trimethoprim-sulfamethoxazole, and pancreatic enzyme supplements.  Temperature is 38.7 C (101.7 F), blood pressure is 125/86 mm Hg, pulse is 108/min, and respirations are 26/min.  On examination, there is moderate respiratory distress with subcostal retractions and tachypnea.  Lung auscultation demonstrates diffuse crackles bilaterally.  There are no murmurs, rubs, or gallops.  The abdomen is soft and nontender.  Chest x-ray reveals diffuse interstitial infiltrates and a small amount of fluid at the bilateral lung bases.  Which of the following is the most likely etiology of this patient's presentation?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d942_4af2_bc81_ff9a92cde186_MD0003_00 This patient has pneumonitis (ie, dyspnea, diffuse interstitial infiltrates, fever) 3 months after bilateral lung transplant. Complications of organ transplant usually reflect rejection and/or infection. Transplanted lungs are especially prone to opportunistic infections because they are immunocompromised and constantly exposed to the environment. The most common opportunistic pathogens are cytomegalovirus (CMV), Pneumocystis, and invasive molds (Aspergillus). CMV pneumonitis, a leading infectious complication in the first year after transplant, presents as an acute (ie, days), febrile, and diffuse interstitial pneumonia (eg, interstitial infiltrates; small, reactive pleural effusions). CMV pneumonitis is most common when the donor and/or recipient is seropositive (D+/R+), reflecting reactivation of latent CMV from the donor's lungs or the recipient's immune cells. Antiviral therapy (eg, valganciclovir) is increasingly given as primary prophylaxis. Pneumocystis pneumonia also presents with fever and diffuse interstitial infiltrates. However, it is usually more indolent (ie, weeks) and unlikely to occur in patients taking appropriate antibiotic prophylaxis (eg, trimethoprim-sulfamethoxazole) (Choice D). Acute cellular rejection (ACR) can also present with respiratory dysfunction, new infiltrates, and fever. It cannot be excluded without histology. ACR is often precipitated by infection (eg, CMV pneumonitis causing tissue damage and allosensitization to donor lung antigens). For this reason, ACR and infection may occur concurrently. Any lung transplant recipient with new infiltrates and fever should undergo a comprehensive workup for both ACR and infection, often with bronchoscopy and lung biopsy. (Choice A) Allergic bronchopulmonary aspergillosis presents as difficult-to-control asthma in patients with structural airway disease (eg, cystic fibrosis prior to transplant); in contrast, after lung transplant, patients are at higher risk for invasive, necrotizing aspergillosis (eg, hemoptysis, halo sign on chest x-ray) due to their immunocompromised status. (Choice B) Chronic graft rejection occurs in the late transplant period (>1 yr) and presents with progressive airflow fibrosis, leading to obstruction and wheezing, not interstitial pneumonitis and crackles. CMV pneumonitis is a major risk factor for chronic rejection. (Choice E) Cystic fibrosis does not recur after lung transplant because all defective airway chloride channels have been replaced by functional channels in the transplanted lung. Educational objective: Cytomegalovirus (CMV) pneumonitis, an acute, febrile, and diffuse pneumonia, is a common opportunistic infection in the first year after lung transplant. It is usually due to reactivation of latent CMV from the donor lung or recipient leukocytes. Tissue injury caused by CMV pneumonitis leads to increased risk of graft rejection and decreased survival.

A 19-Year-Old Woman Comes to the Emergency Department Due to Shortness